Kerberos V5 System Administrator's Guide


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Copyright

Copyright © 1985-2007 by the Massachusetts Institute of Technology.

Export of software employing encryption from the United States of America may require a specific license from the United States Government. It is the responsibility of any person or organization contemplating export to obtain such a license before exporting.

WITHIN THAT CONSTRAINT, permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of M.I.T. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. Furthermore if you modify this software you must label your software as modified software and not distribute it in such a fashion that it might be confused with the original MIT software. M.I.T. makes no representations about the suitability of this software for any purpose. It is provided “as is” without express or implied warranty.

Individual source code files are copyright MIT, Cygnus Support, Novell, OpenVision Technologies, Oracle, Red Hat, Sun Microsystems, FundsXpress, and others.

Project Athena, Athena, Athena MUSE, Discuss, Hesiod, Kerberos, Moira, and Zephyr are trademarks of the Massachusetts Institute of Technology (MIT). No commercial use of these trademarks may be made without prior written permission of MIT.

“Commercial use” means use of a name in a product or other for-profit manner. It does NOT prevent a commercial firm from referring to the MIT trademarks in order to convey information (although in doing so, recognition of their trademark status should be given).

The following copyright and permission notice applies to the OpenVision Kerberos Administration system located in kadmin/create, kadmin/dbutil, kadmin/passwd, kadmin/server, lib/kadm5, and portions of lib/rpc:

Copyright, OpenVision Technologies, Inc., 1996, All Rights Reserved

WARNING: Retrieving the OpenVision Kerberos Administration system source code, as described below, indicates your acceptance of the following terms. If you do not agree to the following terms, do not retrieve the OpenVision Kerberos administration system.

You may freely use and distribute the Source Code and Object Code compiled from it, with or without modification, but this Source Code is provided to you “AS IS” EXCLUSIVE OF ANY WARRANTY, INCLUDING, WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, OR ANY OTHER WARRANTY, WHETHER EXPRESS OR IMPLIED. IN NO EVENT WILL OPENVISION HAVE ANY LIABILITY FOR ANY LOST PROFITS, LOSS OF DATA OR COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, INCLUDING, WITHOUT LIMITATION, THOSE RESULTING FROM THE USE OF THE SOURCE CODE, OR THE FAILURE OF THE SOURCE CODE TO PERFORM, OR FOR ANY OTHER REASON.

OpenVision retains all copyrights in the donated Source Code. OpenVision also retains copyright to derivative works of the Source Code, whether created by OpenVision or by a third party. The OpenVision copyright notice must be preserved if derivative works are made based on the donated Source Code.

OpenVision Technologies, Inc. has donated this Kerberos Administration system to MIT for inclusion in the standard Kerberos 5 distribution. This donation underscores our commitment to continuing Kerberos technology development and our gratitude for the valuable work which has been performed by MIT and the Kerberos community.

Portions contributed by Matt Crawford <crawdad@fnal.gov> were work performed at Fermi National Accelerator Laboratory, which is operated by Universities Research Association, Inc., under contract DE-AC02-76CHO3000 with the U.S. Department of Energy.

Portions of src/lib/crypto have the following copyright:

Copyright © 1998 by the FundsXpress, INC.

All rights reserved.

Export of this software from the United States of America may require a specific license from the United States Government. It is the responsibility of any person or organization contemplating export to obtain such a license before exporting.

WITHIN THAT CONSTRAINT, permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of FundsXpress. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. FundsXpress makes no representations about the suitability of this software for any purpose. It is provided “as is” without express or implied warranty.

THIS SOFTWARE IS PROVIDED “AS IS” AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

The implementation of the Yarrow pseudo-random number generator in src/lib/crypto/yarrow has the following copyright:

Copyright 2000 by Zero-Knowledge Systems, Inc.

Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of Zero-Knowledge Systems, Inc. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. Zero-Knowledge Systems, Inc. makes no representations about the suitability of this software for any purpose. It is provided “as is” without express or implied warranty.

ZERO-KNOWLEDGE SYSTEMS, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL ZERO-KNOWLEDGE SYSTEMS, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTUOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

The implementation of the AES encryption algorithm in src/lib/crypto/aes has the following copyright:

Copyright © 2001, Dr Brian Gladman <brg@gladman.uk.net>, Worcester, UK.
All rights reserved.

LICENSE TERMS

The free distribution and use of this software in both source and binary form is allowed (with or without changes) provided that:

  1. distributions of this source code include the above copyright notice, this list of conditions and the following disclaimer;
  2. distributions in binary form include the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other associated materials;
  3. the copyright holder's name is not used to endorse products built using this software without specific written permission.

DISCLAIMER

This software is provided 'as is' with no explcit or implied warranties in respect of any properties, including, but not limited to, correctness and fitness for purpose.

Portions contributed by Red Hat, including the pre-authentication plug-in framework, contain the following copyright:

Copyright © 2006 Red Hat, Inc.
Portions copyright © 2006 Massachusetts Institute of Technology
All Rights Reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The implementations of GSSAPI mechglue in GSSAPI-SPNEGO in src/lib/gssapi, including the following files:

     lib/gssapi/generic/gssapi_err_generic.et
     lib/gssapi/mechglue/g_accept_sec_context.c
     lib/gssapi/mechglue/g_acquire_cred.c
     lib/gssapi/mechglue/g_canon_name.c
     lib/gssapi/mechglue/g_compare_name.c
     lib/gssapi/mechglue/g_context_time.c
     lib/gssapi/mechglue/g_delete_sec_context.c
     lib/gssapi/mechglue/g_dsp_name.c
     lib/gssapi/mechglue/g_dsp_status.c
     lib/gssapi/mechglue/g_dup_name.c
     lib/gssapi/mechglue/g_exp_sec_context.c
     lib/gssapi/mechglue/g_export_name.c
     lib/gssapi/mechglue/g_glue.c
     lib/gssapi/mechglue/g_imp_name.c
     lib/gssapi/mechglue/g_imp_sec_context.c
     lib/gssapi/mechglue/g_init_sec_context.c
     lib/gssapi/mechglue/g_initialize.c
     lib/gssapi/mechglue/g_inquire_context.c
     lib/gssapi/mechglue/g_inquire_cred.c
     lib/gssapi/mechglue/g_inquire_names.c
     lib/gssapi/mechglue/g_process_context.c
     lib/gssapi/mechglue/g_rel_buffer.c
     lib/gssapi/mechglue/g_rel_cred.c
     lib/gssapi/mechglue/g_rel_name.c
     lib/gssapi/mechglue/g_rel_oid_set.c
     lib/gssapi/mechglue/g_seal.c
     lib/gssapi/mechglue/g_sign.c
     lib/gssapi/mechglue/g_store_cred.c
     lib/gssapi/mechglue/g_unseal.c
     lib/gssapi/mechglue/g_userok.c
     lib/gssapi/mechglue/g_utils.c
     lib/gssapi/mechglue/g_verify.c
     lib/gssapi/mechglue/gssd_pname_to_uid.c
     lib/gssapi/mechglue/mglueP.h
     lib/gssapi/mechglue/oid_ops.c
     lib/gssapi/spnego/gssapiP_spnego.h
     lib/gssapi/spnego/spnego_mech.c

are subject to the following license:

Copyright © 2004 Sun Microsystems, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Kerberos V5 includes documentation and software developed at the University of California at Berkeley, which includes this copyright notice:

Copyright © 1983 Regents of the University of California.
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
  3. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Portions contributed by Novell, Inc., including the LDAP database backend, are subject to the following license:

Copyright (c) 2004-2005, Novell, Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Portions funded by Sandia National Laboratory and developed by the University of Michigan's Center for Information Technology Integration, including the PKINIT implementation, are subject to the following license:

COPYRIGHT © 2006-2007
THE REGENTS OF THE UNIVERSITY OF MICHIGAN
ALL RIGHTS RESERVED

Permission is granted to use, copy, create derivative works and redistribute this software and such derivative works for any purpose, so long as the name of The University of Michigan is not used in any advertising or publicity pertaining to the use of distribution of this software without specific, written prior authorization. If the above copyright notice or any other identification of the University of Michigan is included in any copy of any portion of this software, then the disclaimer below must also be included.

THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

The pkcs11.h file included in the PKINIT code has the following license:

Copyright 2006 g10 Code GmbH Copyright 2006 Andreas Jellinghaus

This file is free software; as a special exception the author gives unlimited permission to copy and/or distribute it, with or without modifications, as long as this notice is preserved.

This file is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY, to the extent permitted by law; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notices and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions.


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1 Introduction


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1.1 Why Should I use Kerberos?

Since Kerberos negotiates authenticated, and optionally encrypted, communications between two points anywhere on the internet, it provides a layer of security that is not dependent on which side of a firewall either client is on. Since studies have shown that half of the computer security breaches in industry happen from inside firewalls, Kerberos V5 from MIT will play a vital role in the security of your network.


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1.2 Documentation for Kerberos V5

This document is one piece of the document set for Kerberos V5. The documents, and their intended audiences, are:


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1.3 Overview of This Guide

The next chapter describes how Kerberos works.

Chapter three describes administration of the principals in the Kerberos database.

Chapter four describes how you can use DNS in configuring your Kerberos realm.

Chapter five describes administrative programs for manipulating the Kerberos database as a whole.

Chapter six describes OpenLDAP Configuration steps.

Chapter seven describes issues to consider when adding an application server to the database.

Chapter eight describes our problem reporting system.

The appendices include the list of Kerberos error messages, and a complete list of the time zones understood by kadmin.


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2 How Kerberos Works

This section provides a simplified description of a general user's interaction with the Kerberos system. This interaction happens transparently—users don't need to know and probably don't care about what's going on—but Kerberos administrators might find a schematic description of the process useful. This description glosses over a lot of details; for more information, see Kerberos: An Authentication Service for Open Network Systems, a paper presented at Winter USENIX 1988, in Dallas, Texas. This paper can be retreived by FTP from athena-dist.mit.edu, in the location: /pub/ATHENA/kerberos/doc/usenix.PS.


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2.1 Network Services and Their Client Programs

In an environment that provides network services, you use client programs to request services from server programs that are somewhere on the network. Suppose you have logged in to a workstation and you want to rlogin to a typical UNIX host. You use the local rlogin client program to contact the remote machine's rlogind daemon.


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2.2 Kerberos Tickets

Under Kerberos, the klogind daemon allows you to login to a remote machine if you can provide klogind a Kerberos ticket which proves your identity. In addition to the ticket, you must also have possession of the corresponding ticket session key. The combination of a ticket and the ticket's session key is known as a credential.

Typically, a client program automatically obtains credentials identifying the person using the client program. The credentials are obtained from a Kerberos server that resides somewhere on the network. A Kerberos server maintains a database of user, server, and password information.


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2.3 The Kerberos Database

Kerberos will give you credentials only if you have an entry in the Kerberos server's Kerberos database. Your database entry includes your Kerberos principal (an identifying string, which is often just your username), and your Kerberos password. Every Kerberos user must have an entry in this database.


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2.4 Kerberos Realms

Each administrative domain will have its own Kerberos database, which contains information about the users and services for that particular site or administrative domain. This administrative domain is the Kerberos realm.

Each Kerberos realm will have at least one Kerberos server, where the master Kerberos database for that site or administrative domain is stored. A Kerberos realm may also have one or more slave servers, which have read-only copies of the Kerberos database that are periodically propagated from the master server. For more details on how this is done, see the “Set Up the Slave KDCs for Database Propagation” and “Propagate the Database to Each Slave KDC” sections of the Kerberos V5 Installation Guide.


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2.5 The Ticket-Granting Ticket

The kinit command prompts for your password. If you enter it successfully, you will obtain a ticket-granting ticket and a ticket session key which gives you the right to use the ticket. This combination of the ticket and its associated key is known as your credentials. As illustrated below, client programs use your ticket-granting ticket credentials in order to obtain client-specific credentials as needed.

Your credentials are stored in a credentials cache, which is often just a file in /tmp. The credentials cache is also called the ticket file, especially in Kerberos V4 documentation. Note, however, that a credentials cache does not have to be stored in a file.


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2.6 Network Services and the Master Database

The master database also contains entries for all network services that require Kerberos authentication. Suppose that your site has a machine, laughter.mit.edu, that requires Kerberos authentication from anyone who wants to rlogin to it. The host's Kerberos realm is ATHENA.MIT.EDU.

This service must be registered in the Kerberos database, using the proper service name, which in this case is the principal:

     host/laughter.mit.edu@ATHENA.MIT.EDU

The / character separates the Kerberos primary (in this case, host) from the instance (in this case, laughter.mit.edu); the @ character separates the realm name (in this case, ATHENA.MIT.EDU) from the rest of the principal. The primary, host, denotes the name or type of the service that is being offered: generic host-level access to the machine. The instance, laughter.mit.edu, names the specific machine that is offering this service. There will generally be many different machines, each offering one particular type of service, and the instance serves to give each one of these servers a different Kerberos principal.


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2.6.1 The Keytab File

For each service, there must also be a service key known only by Kerberos and the service. On the Kerberos server, the service key is stored in the Kerberos database.

On the server host, these service keys are stored in key tables, which are files known as keytabs.1 For example, the service keys used by services that run as root are usually stored in the keytab file /etc/krb5.keytab. N.B.: This service key is the equivalent of the service's password, and must be kept secure. Data which is meant to be read only by the service is encrypted using this key.


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2.7 The User/Kerberos Interaction

Suppose that you walk up to a host intending to login to it, and then rlogin to the machine laughter. Here's what happens:

  1. You login to the workstation and use the kinit command to get a ticket-granting ticket. This command prompts you for your Kerberos password. (On systems running the Kerberos V5 login program, this may be done as part of the login process, not requiring the user to run a separate program.)
    1. The kinit command sends your request to the Kerberos master server machine. The server software looks for your principal name's entry in the Kerberos database.
    2. If this entry exists, the Kerberos server creates and returns a ticket-granting ticket and the key which allows you to use it, encrypted by your password. If kinit can decrypt the Kerberos reply using the password you provide, it stores this ticket in a credentials cache on your local machine for later use. The name of the credentials cache can be specified in the KRB5CCNAME environment variable. If this variable is not set, the name of the file will be /tmp/krb5cc_<uid>, where <uid> is your UNIX user-id, represented in decimal format.
  2. Now you use the rlogin client to access the machine laughter.
              host% rlogin laughter
         
    1. The rlogin client checks your ticket file to see if you have a ticket for the host service for laughter. You don't, so rlogin uses the credential cache's ticket-granting ticket to make a request to the master server's ticket-granting service.
    2. This ticket-granting service receives the request for a ticket for host/laughter.mit.edu, and looks in the master database for an entry for host/laughter.mit.edu. If the entry exists, the ticket-granting service issues you a ticket for that service. That ticket is also cached in your credentials cache.
    3. The rlogin client now sends that ticket to the laughter klogind service program. The service program checks the ticket by using its own service key. If the ticket is valid, it now knows your identity. If you are allowed to login to laughter (because your username matches one in /etc/passwd, or your Kerberos principal is in the appropriate .k5login file), klogind will let you login.


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2.8 Definitions

Following are definitions of some of the Kerberos terminology.

client
an entity that can obtain a ticket. This entity is usually either a user or a host.
host
a computer that can be accessed over a network.
Kerberos
in Greek mythology, the three-headed dog that guards the entrance to the underworld. In the computing world, Kerberos is a network security package that was developed at MIT.
KDC
Key Distribution Center. A machine that issues Kerberos tickets.
keytab
a key table file containing one or more keys. A host or service uses a keytab file in much the same way as a user uses his/her password.
principal
a string that names a specific entity to which a set of credentials may be assigned. It can have an arbitrary number of components, but generally has three:
primary
the first part of a Kerberos principal. In the case of a user, it is the username. In the case of a service, it is the name of the service.
instance
the second part of a Kerberos principal. It gives information that qualifies the primary. The instance may be null. In the case of a user, the instance is often used to describe the intended use of the corresponding credentials. In the case of a host, the instance is the fully qualified hostname.
realm
the logical network served by a single Kerberos database and a set of Key Distribution Centers. By convention, realm names are generally all uppercase letters, to differentiate the realm from the internet domain.

The typical format of a typical Kerberos principal is primary/instance@REALM.

service
any program or computer you access over a network. Examples of services include “host” (a host, e.g., when you use telnet and rsh), “ftp” (FTP), “krbtgt” (authentication; cf. ticket-granting ticket), and “pop” (email).
ticket
a temporary set of electronic credentials that verify the identity of a client for a particular service.
TGT
Ticket-Granting Ticket. A special Kerberos ticket that permits the client to obtain additional Kerberos tickets within the same Kerberos realm.


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3 Configuration Files


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3.1 Supported Encryption Types

Any tag in the configuration files which requires a list of encryption types can be set to some combination of the following strings.

des-cbc-crc
DES cbc mode with CRC-32
des-cbc-md4
DES cbc mode with RSA-MD4
des-cbc-md5
DES cbc mode with RSA-MD5
des3-cbc-sha1
des3-hmac-sha1
des3-cbc-sha1-kd
triple DES cbc mode with HMAC/sha1
des-hmac-sha1
DES with HMAC/sha1
aes256-cts-hmac-sha1-96
aes256-cts
AES-256 CTS mode with 96-bit SHA-1 HMAC
aes128-cts-hmac-sha1-96
aes128-cts
AES-128 CTS mode with 96-bit SHA-1 HMAC
arcfour-hmac
rc4-hmac
arcfour-hmac-md5
RC4 with HMAC/MD5
arcfour-hmac-exp
rc4-hmac-exp
arcfour-hmac-md5-exp
exportable RC4 with HMAC/MD5

While aes128-cts and aes256-cts are supported for all Kerberos operations, they are not supported by older versions of our GSSAPI implementation (krb5-1.3.1 and earlier).

By default, AES is enabled in this release. Sites wishing to use AES encryption types on their KDCs need to be careful not to give GSSAPI services AES keys if the servers have not been updated. If older GSSAPI services are given AES keys, then services may fail when clients supporting AES for GSSAPI are used. Sites may wish to use AES for user keys and for the ticket granting ticket key, although doing so requires specifying what encryption types are used as each principal is created.

If all GSSAPI-based services have been updated before or with the KDC, this is not an issue.


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3.2 Salts

Your Kerberos key is derived from your password. To ensure that people who happen to pick the same password do not have the same key, Kerberos 5 incorporates more information into the key using something called a salt. The supported values for salts are as follows.

normal
default for Kerberos Version 5
v4
the only type used by Kerberos Version 4, no salt
norealm
same as the default, without using realm information
onlyrealm
uses only realm information as the salt
afs3
AFS version 3, only used for compatibility with Kerberos 4 in AFS
special
only used in very special cases; not fully supported


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3.3 krb5.conf

The krb5.conf file contains Kerberos configuration information, including the locations of KDCs and admin servers for the Kerberos realms of interest, defaults for the current realm and for Kerberos applications, and mappings of hostnames onto Kerberos realms. Normally, you should install your krb5.conf file in the directory /etc. You can override the default location by setting the environment variable KRB5_CONFIG.

The krb5.conf file is set up in the style of a Windows INI file. Sections are headed by the section name, in square brackets. Each section may contain zero or more relations, of the form:

     foo = bar

or

     fubar = {
             foo = bar
             baz = quux
     }

Placing a `*' at the end of a line indicates that this is the final value for the tag. This means that neither the remainder of this configuration file nor any other configuration file will be checked for any other values for this tag.

For example, if you have the following lines:

     foo = bar*
     foo = baz

then the second value of foo (baz) would never be read.

The krb5.conf file may contain any or all of the following sections:

libdefaults
Contains default values used by the Kerberos V5 library.
login
Contains default values used by the Kerberos V5 login program.
appdefaults
Contains default values that can be used by Kerberos V5 applications.
realms
Contains subsections keyed by Kerberos realm names. Each subsection describes realm-specific information, including where to find the Kerberos servers for that realm.
domain_realm
Contains relations which map domain names and subdomains onto Kerberos realm names. This is used by programs to determine what realm a host should be in, given its fully qualified domain name.
logging
Contains relations which determine how Kerberos programs are to perform logging.
capaths
Contains the authentication paths used with direct (nonhierarchical) cross-realm authentication. Entries in this section are used by the client to determine the intermediate realms which may be used in cross-realm authentication. It is also used by the end-service when checking the transited field for trusted intermediate realms.


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3.3.1 [libdefaults]

The libdefaults section may contain any of the following relations:

default_keytab_name
This relation specifies the default keytab name to be used by application servers such as telnetd and rlogind. The default is /etc/krb5.keytab.
default_realm
Identifies the default Kerberos realm for the client. Set its value to your Kerberos realm. If this is not specified and the TXT record lookup is enabled (see Using DNS), then that information will be used to determine the default realm. If this tag is not set in this configuration file and there is no DNS information found, then an error will be returned.
default_tgs_enctypes
Identifies the supported list of session key encryption types that should be returned by the KDC. The list may be delimited with commas or whitespace. Kerberos supports many different encryption types, and support for more is planned in the future. (see Supported Encryption Types for a list of the accepted values for this tag). The default value is aes256-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 des-cbc-crc des-cbc-md5 des-cbc-md4.
default_tkt_enctypes
Identifies the supported list of session key encryption types that should be requested by the client. The format is the same as for default_tgs_enctypes. The default value for this tag is aes256-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 des-cbc-crc des-cbc-md5 des-cbc-md4.
permitted_enctypes
Identifies all encryption types that are permitted for use in session key encryption. The default value for this tag is aes256-cts-hmac-sha1-96 des3-cbc-sha1 arcfour-hmac-md5 des-cbc-crc des-cbc-md5 des-cbc-md4.
clockskew
Sets the maximum allowable amount of clockskew in seconds that the library will tolerate before assuming that a Kerberos message is invalid. The default value is 300 seconds, or five minutes.
kdc_timesync
If this is set to 1 (for true), then client machines will compute the difference between their time and the time returned by the KDC in the timestamps in the tickets and use this value to correct for an inaccurate system clock. This corrective factor is only used by the Kerberos library. The default is 1.
kdc_req_checksum_type
ap_req_checksum_type
safe_checksum_type
An integer which specifies the type of checksum to use. Used for compatability with DCE security servers which do not support the default RSA MD5 used by this version of Kerberos. The possible values and their meanings are as follows.
1
CRC32
2
RSA MD4
3
RSA MD4 DES
4
DES CBC
7
RSA MD5
8
RSA MD5 DES
9
NIST SHA
12
HMAC SHA1 DES3
-138
Microsoft MD5 HMAC checksum type
ccache_type
Use this parameter on systems which are DCE clients, to specify the type of cache to be created by kinit, or when forwarded tickets are received. DCE and Kerberos can share the cache, but some versions of DCE do not support the default cache as created by this version of Kerberos. Use a value of 1 on DCE 1.0.3a systems, and a value of 2 on DCE 1.1 systems. The default value is 4.
krb4_srvtab
Specifies the location of the Kerberos V4 srvtab file. Default is /etc/srvtab.
krb4_config
Specifies the location of hte Kerberos V4 configuration file. Default is /etc/krb.conf.
krb4_realms
Specifies the location of the Kerberos V4 domain/realm translation file. Default is /etc/krb.realms.
dns_lookup_kdc
Indicate whether DNS SRV records should be used to locate the KDCs and other servers for a realm, if they are not listed in the information for the realm. (Note that the admin_server entry must be in the file, because the DNS implementation for it is incomplete.)

Enabling this option does open up a type of denial-of-service attack, if someone spoofs the DNS records and redirects you to another server. However, it's no worse than a denial of service, because that fake KDC will be unable to decode anything you send it (besides the initial ticket request, which has no encrypted data), and anything the fake KDC sends will not be trusted without verification using some secret that it won't know.

If this option is not specified but dns_fallback is, that value will be used instead. If neither option is specified, the behavior depends on configure-time options; if none were given, the default is to enable this option. If the DNS support is not compiled in, this entry has no effect.

dns_lookup_realm
Indicate whether DNS TXT records should be used to determine the Kerberos realm of a host.

Enabling this option may permit a redirection attack, where spoofed DNS replies persuade a client to authenticate to the wrong realm, when talking to the wrong host (either by spoofing yet more DNS records or by intercepting the net traffic). Depending on how the client software manages hostnames, however, it could already be vulnerable to such attacks. We are looking at possible ways to minimize or eliminate this exposure. For now, we encourage more adventurous sites to try using Secure DNS.

If this option is not specified but dns_fallback is, that value will be used instead. If neither option is specified, the behavior depends on configure-time options; if none were given, the default is to disable this option. If the DNS support is not compiled in, this entry has no effect.

dns_fallback
General flag controlling the use of DNS for Kerberos information. If both of the preceding options are specified, this option has no effect.
extra_addresses
This allows a computer to use multiple local addresses, in order to allow Kerberos to work in a network that uses NATs. The addresses should be in a comma-separated list.
udp_preference_limit
When sending a message to the KDC, the library will try using TCP before UDP if the size of the message is above udp_preference_list. If the message is smaller than udp_preference_list, then UDP will be tried before TCP. Regardless of the size, both protocols will be tried if the first attempt fails.
verify_ap_req_nofail
If this flag is set, then an attempt to get initial credentials will fail if the client machine does not have a keytab. The default for the flag is not set.
renew_lifetime
The value of this tag is the default renewable lifetime for initial tickets. The default value for the tag is 0.
noaddresses
Setting this flag causes the initial Kerberos ticket to be addressless. The default for the flag is set.
forwardable
If this flag is set, initial tickets by default will be forwardable. The default value for this flag is not set.
proxiable
If this flag is set, initial tickets by default will be proxiable. The default value for this flag is not set.


Next: , Previous: libdefaults, Up: krb5.conf

3.3.2 [appdefaults]

Each tag in the [appdefaults] section names a Kerberos V5 application or an option that is used by some Kerberos V5 application[s]. The value of the tag defines the default behaviors for that application.

For example:

     [appdefaults]
         telnet = {
             ATHENA.MIT.EDU = {
                  option1 = false
             }
         }
         telnet = {
             option1 = true
             option2 = true
         }
         ATHENA.MIT.EDU = {
             option2 = false
         }
         option2 = true

The above four ways of specifying the value of an option are shown in order of decreasing precedence. In this example, if telnet is running in the realm EXAMPLE.COM, it should, by default, have option1 and option2 set to true. However, a telnet program in the realm ATHENA.MIT.EDU should have option1 set to false and option2 set to true. Any other programs in ATHENA.MIT.EDU should have option2 set to false by default. Any programs running in other realms should have option2 set to true.

The list of specifiable options for each application may be found in that application's man pages. The application defaults specified here are overridden by those specified in the [realms] section.

A special application name (afs_krb5) is used by the krb524 service to know whether new format AFS tokens based on Kerberos 5 can be used rather than the older format which used a converted Kerberos 4 ticket. The new format allows for cross-realm authentication without introducing a security hole. It is used by default. Older AFS servers (before OpenAFS 1.2.8) will not support the new format. If servers in your cell do not support the new format, you will need to add an afs_krb5 relation to the appdefaults section. The following config file shows how to disable new format AFS tickets for the afs.example.com cell in the EXAMPLE.COM realm.

     [appdefaults]
         afs_krb5 = {
             EXAMPLE.COM = {
                 afs/afs.example.com = false
             }
         }


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3.3.3 [login]

Each tag in the [login] section of the file is an option for login.krb5. This section may contain any of the following relations:

krb5_get_tickets
Indicate whether or not to use a user's password to get V5 tickets. The default value is true.
krb4_get_tickets
Indicate whether or not to user a user's password to get V4 tickets. The default value is false.
krb4_convert
Indicate whether or not to use the Kerberos conversion daemon to get V4 tickets. The default value is false. If this is set to false and krb4_get_tickets is true, then login will get the V5 tickets directly using the Kerberos V4 protocol directly. This does not currently work with non-MIT-V4 salt types (such as the AFS3 salt type). Note that if this is set to true and krb524d is not running, login will hang for approximately a minute under Solaris, due to a Solaris socket emulation bug.
krb_run_aklog
Indicate whether or not to run aklog. The default value is false.
aklog_path
Indicate where to find aklog. The default value is $(prefix)/bin/aklog.
accept_passwd
A true value will cause login not to accept plaintext passwords. The default value is false. This is not yet implemented.


Next: , Previous: login, Up: krb5.conf

3.3.4 [realms]

Each tag in the [realms] section of the file is the name of a Kerberos realm. The value of the tag is a subsection with relations that define the properties of that particular realm. For each realm, the following tags may be specified in the realm's subsection:

kdc
The name of a host running a KDC for that realm. An optional port number (separated from the hostname by a colon) may be included. For your computer to be able to communicate with the KDC for each realm, this tag must be given a value in each realm subsection in the configuration file, or there must be DNS SRV records specifying the KDCs (see Using DNS).
master_kdc
Identifies the master KDC(s). Currently, this tag is used in only one case: If an attempt to get credentials fails because of an invalid password, the client software will attempt to contact the master KDC, in case the user's password has just been changed, and the updated database has not been propagated to the slave servers yet. (We don't currently check whether the KDC from which the initial response came is on the master KDC list. That may be fixed in the future.)
database_module
This relation indicates the name of the configuration section under [dbmodules] for database specific parameters used by the loadable database library.
admin_server
Identifies the host where the administration server is running. Typically, this is the master Kerberos server. This tag must be given a value in order to communicate with the kadmin server for the realm.
default_domain
This tag is used for Kerberos 4 compatibility. Kerberos 4 does not require the entire hostname of a server to be in its principal like Kerberos 5 does. This tag provides the domain name needed to produce a full hostname when translating V4 principal names into V5 principal names. All servers in this realm are assumed to be in the domain given as the value of this tag
v4_instance_convert
This subsection allows the administrator to configure exceptions to the default_domain mapping rule. It contains V4 instances (the tag name) which should be translated to some specific hostname (the tag value) as the second component in a Kerberos V5 principal name.
v4_realm
This relation is used by the krb524 library routines when converting a V5 principal name to a V4 principal name. It is used when the V4 realm name and the V5 realm name are not the same, but still share the same principal names and passwords. The tag value is the Kerberos V4 realm name.
auth_to_local_names
This subsection allows you to set explicit mappings from principal names to local user names. The tag is the mapping name, and the value is the corresponding local user name.
auth_to_local
This tag allows you to set a general rule for mapping principal names to local user names. It will be used if there is not an explicit mapping for the principal name that is being translated. The possible values are:
DB:filename
The principal will be looked up in the database filename. Support for this is not currently compiled in by default.
RULE:exp
The local name will be formulated from exp.

The format for exp is [n:$d..string](regexp)s/pattern/replacement/g. The integer n indicates how many components the target principal should have. If this matches, then a string will be formed by putting together the components of the principal in the order indicated by each integer d, and the arbitrary string string (i.e. if the principal was johndoe/admin then [2:$2$1foo] would result in the string "adminjohndoefoo". If this string matches regexp, then the s//[g] substitution command will be run over the string. The optional g will cause the substitution to be global over the string, instead of replacing only the first match in the string.

DEFAULT
The principal name will be used as the local user name. If the principal has more than one component or is not in the default realm, this rule is not applicable and the conversion will fail.

For example:

          [realms]
              ATHENA.MIT.EDU = {
                  auth_to_local = {
                      RULE:[2:$1](johndoe)s/^.*$/guest/
                      RULE:[2:$1;$2](^.*;admin$)s/;admin$//
                      RULE:[2:$2](^.*;root)s/^.*$/root/
                      DEFAULT
                      }
                  }
     

would result in any principal without root or admin as the second component to be translated with the default rule. A principal with a second component of admin will become its first component. root will be used as the local name for any principal with a second component of root. The exception to these two rules are any principals johndoe/*, which will always get the local name guest.


Next: , Previous: realms (krb5.conf), Up: krb5.conf

3.3.5 [domain_realm]

The [domain_realm] section provides a translation from a domain name or hostname to a Kerberos realm name. The tag name can be a host name, or a domain name, where domain names are indicated by a prefix of a period (.). The value of the relation is the Kerberos realm name for that particular host or domain. Host names and domain names should be in lower case.

If no translation entry applies, the host's realm is considered to be the hostname's domain portion converted to upper case. For example, the following [domain_realm] section:

     [domain_realm]
         .mit.edu = ATHENA.MIT.EDU
         mit.edu = ATHENA.MIT.EDU
         crash.mit.edu = TEST.ATHENA.MIT.EDU
         example.com = EXAMPLE.COM

maps crash.mit.edu into the TEST.ATHENA.MIT.EDU realm. All other hosts in the mit.edu domain will map by default to the ATHENA.MIT.EDU realm, and all hosts in the example.com domain will map by default into the EXAMPLE.COM realm. Note the entries for the hosts mit.edu and example.com. Without these entries, these hosts would be mapped into the Kerberos realms EDU and ORG, respectively.


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3.3.6 [logging]

The [logging] section indicates how a particular entity is to perform its logging. The relations in this section assign one or more values to the entity name. Currently, the following entities are used:

kdc
These entries specify how the KDC is to perform its logging.
admin_server
These entries specify how the administrative server is to perform its logging.
default
These entries specify how to perform logging in the absence of explicit specifications otherwise.

Values are of the following forms:

FILE=<filename>
FILE:<filename>
This value causes the entity's logging messages to go to the specified file. If the = form is used, the file is overwritten. If the : form is used, the file is appended to.
STDERR
This value causes the entity's logging messages to go to its standard error stream.
CONSOLE
This value causes the entity's logging messages to go to the console, if the system supports it.
DEVICE=<devicename>
This causes the entity's logging messages to go to the specified device.
SYSLOG[:<severity>[:<facility>]]
This causes the entity's logging messages to go to the system log.

The severity argument specifies the default severity of system log messages. This may be any of the following severities supported by the syslog(3) call, minus the LOG_ prefix: LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR, LOG_WARNING, LOG_NOTICE, LOG_INFO, and LOG_DEBUG. For example, a value of CRIT would specify LOG_CRIT severity.

The facility argument specifies the facility under which the messages are logged. This may be any of the following facilities supported by the syslog(3) call minus the LOG_ prefix: LOG_KERN, LOG_USER, LOG_MAIL, LOG_DAEMON, LOG_AUTH, LOG_LPR, LOG_NEWS, LOG_UUCP, LOG_CRON, and LOG_LOCAL0 through LOG_LOCAL7.

If no severity is specified, the default is ERR. If no facility is specified, the default is AUTH.

In the following example, the logging messages from the KDC will go to the console and to the system log under the facility LOG_DAEMON with default severity of LOG_INFO; and the logging messages from the administrative server will be appended to the file /var/adm/kadmin.log and sent to the device /dev/tty04.

     [logging]
         kdc = CONSOLE
         kdc = SYSLOG:INFO:DAEMON
         admin_server = FILE:/var/adm/kadmin.log
         admin_server = DEVICE=/dev/tty04


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3.3.7 [capaths]

In order to perform direct (non-hierarchical) cross-realm authentication, a database is needed to construct the authentication paths between the realms. This section defines that database.

A client will use this section to find the authentication path between its realm and the realm of the server. The server will use this section to verify the authentication path used by the client, by checking the transited field of the received ticket.

There is a tag for each participating realm, and each tag has subtags for each of the realms. The value of the subtags is an intermediate realm which may participate in the cross-realm authentication. The subtags may be repeated if there is more then one intermediate realm. A value of "." means that the two realms share keys directly, and no intermediate realms should be allowed to participate.

There are n**2 possible entries in this table, but only those entries which will be needed on the client or the server need to be present. The client needs a tag for its local realm, with subtags for all the realms of servers it will need to authenticate with. A server needs a tag for each realm of the clients it will serve.

For example, ANL.GOV, PNL.GOV, and NERSC.GOV all wish to use the ES.NET realm as an intermediate realm. ANL has a sub realm of TEST.ANL.GOV which will authenticate with NERSC.GOV but not PNL.GOV. The [capaths] section for ANL.GOV systems would look like this:

     [capaths]
         ANL.GOV = {
             TEST.ANL.GOV = .
             PNL.GOV = ES.NET
             NERSC.GOV = ES.NET
             ES.NET = .
         }
         TEST.ANL.GOV = {
             ANL.GOV = .
         }
         PNL.GOV = {
             ANL.GOV = ES.NET
         }
         NERSC.GOV = {
             ANL.GOV = ES.NET
         }
         ES.NET = {
             ANL.GOV = .
         }

The [capaths] section of the configuration file used on NERSC.GOV systems would look like this:

     [capaths]
         NERSC.GOV = {
             ANL.GOV = ES.NET
             TEST.ANL.GOV = ES.NET
             TEST.ANL.GOV = ANL.GOV
             PNL.GOV = ES.NET
             ES.NET = .
         }
         ANL.GOV = {
             NERSC.GOV = ES.NET
         }
         PNL.GOV = {
             NERSC.GOV = ES.NET
         }
         ES.NET = {
             NERSC.GOV = .
         }
         TEST.ANL.GOV = {
             NERSC.GOV = ANL.GOV
             NERSC.GOV = ES.NET
         }

In the above examples, the ordering is not important, except when the same subtag name is used more then once. The client will use this to determine the path. (It is not important to the server, since the transited field is not sorted.)

This feature is not currently supported by DCE. DCE security servers can be used with Kerberized clients and servers, but versions prior to DCE 1.1 did not fill in the transited field, and should be used with caution.


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3.3.8 [dbdefaults]

The [dbdefaults] section provides default values for the database specific parameters. It can also specify the configuration section under [dbmodules] section for database specific parameters used by the database library.(see dbmodules).

The following tags are used in this section:

database_module
This relation indicates the name of the configuration section under the [dbmodules] for database specific parameters used by the loadable database library.
ldap_kerberos_container_dn
This LDAP specific tag indicates the DN of the container object where the realm objects will be located. This value is used if the container object is not mentioned in the configuration section under [dbmodules].
ldap_kdc_dn
This LDAP specific tag indicates the default bind DN for the KDC server. The KDC server does a login to the directory as this object. This object should have the rights to read the Kerberos data in the LDAP database. This value is used if the bind DN for the KDC is not mentioned in the configuration section under [dbmodules].
ldap_kadmind_dn
This LDAP specific tag indicates the default bind DN for the Administration server. The administration server does a login to the directory as this object. This object should have the rights to read and write the Kerberos data in the LDAP database. This value is used if the bind DN for the Administration server is not mentioned in the configuration section under [dbmodules].
ldap_service_password_file
This LDAP specific tag indicates the file containing the stashed passwords for the objects used by the Kerberos servers to bind to the LDAP server. This file must be kept secure. This value is used if no service password file is mentioned in the configuration section under [dbmodules].
ldap_server
This LDAP specific tag indicates the list of LDAP servers that the Kerberos servers can connect to. The list of LDAP servers is whitespace-separated. The LDAP server is specified by a LDAP URI. This value is used if no LDAP servers are mentioned in the configuration section under [dbmodules]. It is recommended to use the ldapi:// or ldaps:// interface and not to use ldap:// interface.
ldap_conns_per_server
This LDAP specific tag indicates the number of connections to be maintained per LDAP server. This value is used if the number of connections per LDAP server are not mentioned in the configuration section under [dbmodules]. The default value is 5.


Next: , Previous: dbdefaults, Up: krb5.conf

3.3.9 [dbmodules]

Contains database specific parameters used by the database library. Each tag in the [dbmodules] section of the file names a configuration section for database specific parameters that can be referred to by a realm. The value of the tag is a subsection where the relations in that subsection define the database specific parameters.

For each section, the following tags may be specified in the subsection:

db_library
This tag indicates the name of the loadable database library. The value should be db2 for DB2 database and kldap for LDAP database.
ldap_kerberos_container_dn
This LDAP specific tag indicates the DN of the container object where the realm objects will be located.
ldap_kdc_dn
This LDAP specific tag indicates the default bind DN for the KDC server. The KDC server does a login to the directory as this object. This object should have the rights to read the Kerberos data in the LDAP database.
ldap_kadmind_dn
This LDAP specific tag indicates the default bind DN for the Administration server. The administration server does a login to the directory as this object. This object should have the rights to read and write the Kerberos data in the LDAP database.
ldap_service_password_file
This LDAP specific tag indicates the file containing the stashed passwords for the objects used by the Kerberos servers to bind to the LDAP server. This file must be kept secure.
ldap_server
This LDAP specific tag indicates the list of LDAP servers that the Kerberos servers can connect to. The list of LDAP servers is whitespace-separated. The LDAP server is specified by a LDAP URI. It is recommended to use ldapi:// or ldaps:// interface to connect to the LDAP server.
ldap_conns_per_server
This LDAP specific tags indicates the number of connections to be maintained per LDAP server.


Next: , Previous: dbmodules, Up: krb5.conf

3.3.10 pkinit options

The following are pkinit-specific options. Note that these values may be specified in [libdefaults] as global defaults, or within a realm-specific subsection of [libdefaults], or may be specified as realm-specific values in the [realms] section. Also note that a realm-specific value over-rides, does not add to, a generic [libdefaults] specification. The search order is:

  1. realm-specific subsection of [libdefaults]
              [libdefaults]
                  EXAMPLE.COM = {
                      pkinit_anchors = FILE:/usr/local/example.com.crt
                  }
         
  2. realm-specific value in the [realms] section,
              [realms]
                  OTHERREALM.ORG = {
                      pkinit_anchors = FILE:/usr/local/otherrealm.org.crt
                  }
         
  3. generic value in the [libdefaults] section.
              [libdefaults]
                  pkinit_anchors = DIR:/usr/local/generic_trusted_cas/
         


Next: , Previous: pkinit client options, Up: pkinit client options
3.3.10.1 Specifying pkinit identity information

The syntax for specifying Public Key identity, trust, and revocation information for pkinit is as follows:

FILE:file-name[,key-file-name]
This option has context-specific behavior.
pkinit_identity
pkinit_identities
file-name specifies the name of a PEM-format file containing the user's certificate. If key-file-name is not specified, the user's private key is expected to be in file-name as well. Otherwise, key-file-name is the name of the file containing the private key.
pkinit_anchors
pkinit_pool
file-name is assumed to be the name of an OpenSSL-style ca-bundle file.

DIR:directory-name
This option has context-specific behavior.
pkinit_identity
pkinit_identities
directory-name specifies a directory with files named *.crt and *.key, where the first part of the file name is the same for matching pairs of certificate and private key files. When a file with a name ending with .crt is found, a matching file ending with .key is assumed to contain the private key. If no such file is found, then the certificate in the .crt is not used.
pkinit_anchors
pkinit_pool
directory-name is assumed to be an OpenSSL-style hashed CA directory where each CA cert is stored in a file named hash-of-ca-cert.#. This infrastructure is encouraged, but all files in the directory will be examined and if they contain certificates (in PEM format), they will be used.
pkinit_revoke
directory-name is assumed to be an OpenSSL-style hashed CA directory where each revocation list is stored in a file named hash-of-ca-cert.r#. This infrastructure is encouraged, but all files in the directory will be examined and if they contain a revocation list (in PEM format), they will be used.

PKCS12:pkcs12-file-name
pkcs12-file-name is the name of a PKCS #12 format file, containing the user's certificate and private key.
PKCS11:[module_name=]module-name[:slotid=slot-id][:token=token-label][:certid=cert-id][:certlabel=cert-label]
All keyword/values are optional. module-name specifies the location of a library implementing PKCS #11. If a value is encountered with not keyword, it is assumed to be the module-name. If no module-name is specified, the default is opensc-pkcs11.so. slotid= and/or token= may be specified to force the use of a particular smard card reader or token if there is more than one available. certid= and/or certlabel= may be specified to force the selection of a particular certificate on the device. See the pkinit_cert_match configuration option for more ways to select a particular certificate to use for pkinit.
ENV:environment-variable-name
environment-variable-name specifies the name of an environment variable which has been set to a value conforming to one of the previous values. For example, ENV:X509_PROXY, where environment variable X509_PROXY has been set to FILE:/tmp/my_proxy.pem.


Previous: pkinit identity syntax, Up: pkinit client options
3.3.10.2 pkinit krb5.conf options
pkinit_identities
Specifies the location(s) to be used to find the user's X.509 identity information. This option may be specified multiple times. Each value is attempted in order until identity information is found and authentication is attempted. Note that these values are not used if the user specifies X509_user_identity on the command line.
pkinit_anchors
Specifies the location of trusted anchor (root) certificates which the client trusts to sign KDC certificates. This option may be specified multiple times. These values from the config file are not used if the user specifies X509_anchors on the command line.
pkinit_pool
Specifies the location of intermediate certificates which may be used by the client to complete the trust chain between a KDC certificate and a trusted anchor. This option may be specified multiple times.
pkinit_revoke
Specifies the location of Certificate Revocation List (CRL) information to be used by the client when verifying the validity of the KDC certificate presented. This option may be specified multiple times.
pkinit_require_crl_checking
The default certificate verification process will always check the available revocation information to see if a certificate has been revoked. If a match is found for the certificate in a CRL, verification fails. If the certificate being verified is not listed in a CRL, or there is no CRL present for its issuing CA, and pkinit_require_crl_checking is false, then verification succeeds.

However, if pkinit_require_crl_checking is true and there is no CRL information available for the issuing CA, then verification fails.

pkinit_require_crl_checking should be set to true if the policy is such that up-to-date CRLs must be present for every CA.

pkinit_dh_min_bits
Specifies the size of the Diffie-Hellman key the client will attempt to use. The acceptable values are currently 1024, 2048, and 4096. The default is 2048.
pkinit_win2k
This flag specifies whether the target realm is assumed to support only the old, pre-RFC version of the protocol. The default is false.
pkinit_win2k_require_binding
If this flag is set to true, it expects that the target KDC is patched to return a reply with a checksum rather than a nonce. The default is false.
pkinit_eku_checking
This option specifies what Extended Key Usage value the KDC certificate presented to the client must contain. (Note that if the KDC certificate has the pkinit SubjectAlternativeName encoded as the Kerberos TGS name, EKU checking is not necessary since the issuing CA has certified this as a KDC certificate.) The values recognized in the krb5.conf file are:
kpKDC
This is the default value and specifies that the KDC must have the id-pkinit-KPKdc EKU as defined in RFC4556.
kpServerAuth
If kpServerAuth is specified, a KDC certificate with the id-kp-serverAuth EKU as used by Microsoft will be accepted.
none
If none is specified, then the KDC certificate will not be checked to verify it has an acceptable EKU. The use of this option is not recommended.

pkinit_kdc_hostname
The presense of this option indicates that the client is willing to accept a KDC certificate with a dNSName SAN (Subject Alternative Name) rather than requiring the id-pkinit-san as defined in RFC4556. This option may be specified multiple times. Its value should contain the acceptable hostname for the KDC (as contained in its certificate).
pkinit_cert_match
Specifies matching rules that the client certificate must match before it is used to attempt pkinit authentication. If a user has multiple certificates available (on a smart card, or via other media), there must be exactly one certificate chosen before attempting pkinit authentication. This option may be specified multiple times. All the available certificates are checked against each rule in order until there is a match of exactly one certificate.

The Subject and Issuer comparison strings are the RFC2253 string representations from the certificate Subject DN and Issuer DN values.

The syntax of the matching rules is:

          [relation-operator]component-rule ...
     

where

relation-operator
can be either &&, meaning all component rules must match, or ||, meaning only one component rule must match. The default is && if not specified.
component-rule
can be one of the following. Note that there is no punctuation or whitespace between component rules.
<SUBJECT>regular-expression
<ISSUER>regular-expression
<SAN>regular-expression
<EKU>extended-key-usage-list
where extended-key-usage-list is a comma-separated list of required Extended Key Usage values. All values in the list must be present in the certificate.
                    pkinit
                    msScLogin
                    clientAuth
                    emailProtection
               

<KU>key-usage-list
where key-usage-list is a comma-separated list of required Key Usage values. All values in the list must be present in the certificate.
                    digitalSignature
                    keyEncipherment
               
Examples:
          pkinit_cert_match = ||<SUBJECT>.*DoE.*<SAN>.*@EXAMPLE.COM
          pkinit_cert_match = &&<EKU>msScLogin,clientAuth<ISSUER>.*DoE.*
          pkinit_cert_match = <EKU>msScLogin,clientAuth<KU>digitalSignature
     


Previous: pkinit client options, Up: krb5.conf

3.3.11 Sample krb5.conf File

Here is an example of a generic krb5.conf file:

     [libdefaults]
         default_realm = ATHENA.MIT.EDU
         default_tkt_enctypes = des3-hmac-sha1 des-cbc-crc
         default_tgs_enctypes = des3-hmac-sha1 des-cbc-crc
         dns_lookup_kdc = true
         dns_lookup_realm = false
     
     [realms]
         ATHENA.MIT.EDU = {
             kdc = kerberos.mit.edu
             kdc = kerberos-1.mit.edu
             kdc = kerberos-2.mit.edu:750
             admin_server = kerberos.mit.edu
             master_kdc = kerberos.mit.edu
             default_domain = mit.edu
         }
         EXAMPLE.COM = {
             kdc = kerberos.example.com
             kdc = kerberos-1.example.com
             admin_server = kerberos.example.com
         }
         OPENLDAP.MIT.EDU = {
             kdc = kerberos.mit.edu
             admin_server = kerberos.mit.edu
             database_module = openldap_ldapconf
         }
     
     [domain_realm]
         .mit.edu = ATHENA.MIT.EDU
         mit.edu = ATHENA.MIT.EDU
     
     [capaths]
         ATHENA.MIT.EDU = {
         	EXAMPLE.COM = .
         }
         EXAMPLE.COM = {
         	ATHENA.MIT.EDU = .
         }
     
     [logging]
         kdc = SYSLOG:INFO
         admin_server = FILE=/var/kadm5.log
     [dbdefaults]
         ldap_kerberos_container_dn = cn=krbcontainer,o=mit
     [dbmodules]
         openldap_ldapconf = {
               db_library = kldap
               ldap_kerberos_container_dn = cn=krbcontainer,o=mit
               ldap_kdc_dn = "cn=krbadmin,o=mit"
                  # this object needs to have read rights on
                  # the realm container, principal container and realm sub-trees
               ldap_kadmind_dn = "cn=krbadmin,o=mit"
                  # this object needs to have read and write rights on
                  # the realm container, principal container and realm sub-trees
              ldap_service_password_file = /etc/kerberos/service.keyfile
              ldap_servers = ldaps://kerberos.mit.edu
              ldap_conns_per_server = 5
     }


Previous: krb5.conf, Up: Configuration Files

3.4 kdc.conf

The kdc.conf file contains KDC configuration information, including defaults used when issuing Kerberos tickets. Normally, you should install your kdc.conf file in the directory /usr/local/var/krb5kdc. You can override the default location by setting the environment variable KRB5_KDC_PROFILE.

The kdc.conf file is set up in the same format as the krb5.conf file. (See krb5.conf.) The kdc.conf file may contain any or all of the following three sections:

kdcdefaults
Contains default values for overall behavior of the KDC.
realms
Contains subsections keyed by Kerberos realm names. Each subsection describes realm-specific information, including where to find the Kerberos servers for that realm.
logging
Contains relations which determine how Kerberos programs are to perform logging.


Next: , Previous: kdc.conf, Up: kdc.conf

3.4.1 [kdcdefaults]

The following relation is defined in the [kdcdefaults] section:

kdc_ports
This relation lists the ports on which the Kerberos server should listen for UDP requests by default. This list is a comma separated list of integers. If this relation is not specified, the compiled-in default is 88,750, the first being the assigned Kerberos port and the second which was used by Kerberos V4.
kdc_tcp_ports
This relation lists the ports on which the Kerberos server should listen for TCP connections by default. This list is a comma separated list of integers. If this relation is not specified, the compiled-in default is not to listen for TCP connections at all.

If you wish to change this (which we do not recommend, because the current implementation has little protection against denial-of-service attacks), the standard port number assigned for Kerberos TCP traffic is port 88.

v4_mode
This string specifies how the KDC should respond to Kerberos 4 packets. The possible values are none, disable, full, and nopreauth. The default value is none.


Next: , Previous: kdcdefaults, Up: kdc.conf

3.4.2 [realms]

Each tag in the [realms] section of the file names a Kerberos realm. The value of the tag is a subsection where the relations in that subsection define KDC parameters for that particular realm.

For each realm, the following tags may be specified in the [realms] subsection:

acl_file
(String.) Location of the access control list (acl) file that kadmin uses to determine which principals are allowed which permissions on the database. The default is /usr/local/var/krb5kdc/kadm5.acl.
admin_keytab
(String.) Location of the keytab file that the legacy administration daemons kadmind4 and v5passwdd use to authenticate to the database. The default is /usr/local/var/krb5kdc/kadm5.keytab.
database_name
(String.) Location of the Kerberos database for this realm. The default is
/usr/local/var/krb5kdc/principal.
default_principal_expiration
(Absolute time string.) Specifies the default expiration date of principals created in this realm. The default value for this tag is 0.
default_principal_flags
(Flag string.) Specifies the default attributes of principals created in this realm. The format for this string is a comma-separated list of flags, with '+' before each flag that should be enabled and '-' before each flag that should be disabled. The default is postdateable, forwardable, tgt-based, renewable, proxiable, dup-skey, allow-tickets, and service enabled..

There are a number of possible flags:

postdateable
Enabling this flag allows the principal to obtain postdateable tickets.
forwardable
Enabling this flag allows the principal to obtain forwardable tickets.
tgt-based
Enabling this flag allows a principal to obtain tickets based on a ticket-granting-ticket, rather than repeating the authentication process that was used to obtain the TGT.
renewable
Enabling this flag allows the principal to obtain renewable tickets.
proxiable
Enabling this flag allows the principal to obtain proxy tickets.
dup-skey
Enabling this flag allows the principal to obtain a session key for another user, permitting user-to-user authentication for this principal.
allow-tickets
Enabling this flag means that the KDC will issue tickets for this principal. Disabling this flag essentially deactivates the principal within this realm.
preauth
If this flag is enabled on a client principal, then that principal is required to preauthenticate to the KDC before receiving any tickets. On a service principal, enabling this flag means that service tickets for this principal will only be issued to clients with a TGT that has the preauthenticated ticket set.
hwauth
If this flag is enabled, then the principal is required to preauthenticate using a hardware device before receiving any tickets.
pwchange
Enabling this flag forces a password change for this principal.
service
Enabling this flag allows the the KDC to issue service tickets for this principal.
pwservice
If this flag is enabled, it marks this principal as a password change service. This should only be used in special cases, for example, if a user's password has expired, then the user has to get tickets for that principal without going through the normal password authentication in order to be able to change the password.
dict_file
(String.) Location of the dictionary file containing strings that are not allowed as passwords. If none is specified or if there is no policy assigned to the principal, no dictionary checks of passwords will be performed.
kadmind_port
(Port number.) Specifies the port on which the kadmind daemon is to listen for this realm. The assigned port for kadmind is 749.
kpasswd_port
(Port number.) Specifies the port on which the kpasswd daemon is to listen for this realm. The default is 464.
key_stash_file
(String.) Specifies the location where the master key has been stored (via kdb5_util stash). The default is /usr/local/var/krb5kdc/.k5.REALM, where REALM is the Kerberos realm.
kdc_ports
(String.) Specifies the list of ports that the KDC is to listen to for UDP requests for this realm. By default, the value of kdc_ports as specified in the [kdcdefaults] section is used.
kdc_tcp_ports
(String.) Specifies the list of ports that the KDC is to listen to for TCP requests for this realm. By default, the value of kdc_tcp_ports as specified in the [kdcdefaults] section is used.
master_key_name
(String.) Specifies the name of the principal associated with the master key. The default is K/M.
master_key_type
(Key type string.) Specifies the master key's key type. The default value for this is des3-cbc-sha1. For a list of all possible values, see Supported Encryption Types.
max_life
(Delta time string.) Specifes the maximum time period for which a ticket may be valid in this realm. The default value is 10 hours.
max_renewable_life
(Delta time string.) Specifies the maximum time period during which a valid ticket may be renewed in this realm. The default value is 0.
supported_enctypes
List of key:salt strings. Specifies the default key/salt combinations of principals for this realm. Any principals created through kadmin will have keys of these types. The default value for this tag is des3-hmac-sha1:normal des-cbc-crc:normal. For lists of possible values, see Supported Encryption Types and Salts.
reject_bad_transit
A boolean value (true, false). If set to true, the KDC will check the list of transited realms for cross-realm tickets against the transit path computed from the realm names and the capaths section of its krb5.conf file; if the path in the ticket to be issued contains any realms not in the computed path, the ticket will not be issued, and an error will be returned to the client instead. If this value is set to false, such tickets will be issued anyways, and it will be left up to the application server to validate the realm transit path.

If the disable-transited-check flag is set in the incoming request, this check is not performed at all. Having the reject_bad_transit option will cause such ticket requests to be rejected always.

This transit path checking and config file option currently apply only to TGS requests.

Earlier versions of the MIT release (before 1.2.3) had bugs in the application server support such that the server-side checks may not be performed correctly. We recommend turning this option on, unless you know that all application servers in this realm have been updated to fixed versions of the software, and for whatever reason, you don't want the KDC to do the validation.

This is a per-realm option so that multiple-realm KDCs may control it separately for each realm, in case (for example) one realm has had the software on its application servers updated but another has not.

This option defaults to true.


Next: , Previous: realms (kdc.conf), Up: kdc.conf

3.4.3 pkinit options

The following are pkinit-specific options. Note that these values may be specified in [kdcdefaults] as global defaults, or within a realm-specific subsection of [realms]. Also note that a realm-specific value over-rides, does not add to, a generic [kdcdefaults] specification. The search order is:

  1. realm-specific subsection of [realms]
              [realms]
                  EXAMPLE.COM = {
                      pkinit_anchors = FILE:/usr/local/example.com.crt
                  }
         
  2. generic value in the [kdcdefaults] section.
              [kdcdefaults]
                  pkinit_anchors = DIR:/usr/local/generic_trusted_cas/
         


Previous: pkinit kdc options, Up: pkinit kdc options
3.4.3.1 pkinit kdc.conf options

For information about the syntax of some of these options, see See pkinit identity syntax.

pkinit_identity
Specifies the location of the KDC's X.509 identity information. This option is required if pkinit is to be supported by the KDC.
pkinit_anchors
Specifies the location of trusted anchor (root) certificates which the KDC trusts to sign client certificates. This option is required if pkinit is to be supported by the KDC. This option may be specified multiple times.
pkinit_pool
Specifies the location of intermediate certificates which may be used by the KDC to complete the trust chain between a client's certificate and a trusted anchor. This option may be specified multiple times.
pkinit_revoke
Specifies the location of Certificate Revocation List (CRL) information to be used by the KDC when verifying the validity of client certificates. This option may be specified multiple times.
pkinit_require_crl_checking
The default certificate verification process will always check the available revocation information to see if a certificate has been revoked. If a match is found for the certificate in a CRL, verification fails. If the certificate being verified is not listed in a CRL, or there is no CRL present for its issuing CA, and pkinit_require_crl_checking is false, then verification succeeds.

However, if pkinit_require_crl_checking is true and there is no CRL information available for the issuing CA, then verification fails.

pkinit_require_crl_checking should be set to true if the policy is such that up-to-date CRLs must be present for every CA.

pkinit_dh_min_bits
Specifies the minimum number of bits the KDC is willing to accept for a client's Diffie-Hellman key. The default is 2048.
pkinit_allow_upn
Specifies that the KDC is willing to accept client certificates with the Microsoft UserPrincipalName (UPN) Subject Alternative Name (SAN). This means the KDC accepts the binding of the UPN in the certificate to the Kerberos principal name.

The default is false.

Without this option, the KDC will only accept certificates with the id-pkinit-san as defined in RFC4556. There is currently no option to disable SAN checking in the KDC.

pkinit_eku_checking
This option specifies what Extended Key Usage (EKU) values the KDC is willing to accept in client certificates. The values recognized in the kdc.conf file are:
kpClientAuth
This is the default value and specifies that client certificates must have the id-pkinit-KPClientAuth EKU as defined in RFC4556.
scLogin
If scLogin is specified, client certificates with the Microsoft Smart Card Login EKU (id-ms-kp-sc-logon) will be accepted.
none
If none is specified, then client certificates will not be checked to verify they have an acceptable EKU. The use of this option is not recommended.


Previous: pkinit kdc options, Up: kdc.conf

3.4.4 Sample kdc.conf File

Here's an example of a kdc.conf file:

     [kdcdefaults]
         kdc_ports = 88
     
     [realms]
         ATHENA.MIT.EDU = {
             kadmind_port = 749
             max_life = 12h 0m 0s
             max_renewable_life = 7d 0h 0m 0s
             master_key_type = des3-hmac-sha1
             supported_enctypes = des3-hmac-sha1:normal des-cbc-crc:normal des-cbc-crc:v4
         }
     
     [logging]
         kdc = FILE:/usr/local/var/krb5kdc/kdc.log
         admin_server = FILE:/usr/local/var/krb5kdc/kadmin.log


Next: , Previous: Configuration Files, Up: Top

4 Using DNS


Next: , Previous: Using DNS, Up: Using DNS

4.1 Mapping Hostnames onto Kerberos Realms

Mapping hostnames onto Kerberos realms is done in one of two ways.

The first mechanism, which has been in use for years in MIT-based Kerberos distributions, works through a set of rules in the krb5.conf configuration file. (See krb5.conf.) You can specify mappings for an entire domain or subdomain, and/or on a hostname-by-hostname basis. Since greater specificity takes precedence, you would do this by specifying the mappings for a given domain or subdomain and listing the exceptions.

The second mechanism works by looking up the information in special TXT records in the Domain Name Service. This is currently not used by default because security holes could result if the DNS TXT records were spoofed. If this mechanism is enabled on the client, it will try to look up a TXT record for the DNS name formed by putting the prefix _kerberos in front of the hostname in question. If that record is not found, it will try using _kerberos and the host's domain name, then its parent domain, and so forth. So for the hostname BOSTON.ENGINEERING.FOOBAR.COM, the names looked up would be:

     _kerberos.boston.engineering.foobar.com
     _kerberos.engineering.foobar.com
     _kerberos.foobar.com
     _kerberos.com

The value of the first TXT record found is taken as the realm name. (Obviously, this doesn't work all that well if a host and a subdomain have the same name, and different realms. For example, if all the hosts in the ENGINEERING.FOOBAR.COM domain are in the ENGINEERING.FOOBAR.COM realm, but a host named ENGINEERING.FOOBAR.COM is for some reason in another realm. In that case, you would set up TXT records for all hosts, rather than relying on the fallback to the domain name.)

Even if you do not choose to use this mechanism within your site, you may wish to set it up anyway, for use when interacting with other sites.


Previous: Mapping Hostnames onto Kerberos Realms, Up: Using DNS

4.2 Hostnames for KDCs

MIT recommends that your KDCs have a predefined set of CNAME records (DNS hostname aliases), such as kerberos for the master KDC and kerberos-1, kerberos-2, ... for the slave KDCs. This way, if you need to swap a machine, you only need to change a DNS entry, rather than having to change hostnames.

A new mechanism for locating KDCs of a realm through DNS has been added to the MIT Kerberos V5 distribution. A relatively new record type called SRV has been added to DNS. Looked up by a service name and a domain name, these records indicate the hostname and port number to contact for that service, optionally with weighting and prioritization. (See RFC 2782 if you want more information. You can follow the example below for straightforward cases.)

The use with Kerberos is fairly straightforward. The domain name used in the SRV record name is the domain-style Kerberos realm name. (It is possible to have Kerberos realm names that are not DNS-style names, but we don't recommend it for Internet use, and our code does not support it well.) Several different Kerberos-related service names are used:

_kerberos._udp
This is for contacting any KDC by UDP. This entry will be used the most often. Normally you should list port 88 on each of your KDCs.
_kerberos._tcp
This is for contacting any KDC by TCP. The MIT KDC by default will not listen on any TCP ports, so unless you've changed the configuration or you're running another KDC implementation, you should leave this unspecified. If you do enable TCP support, normally you should use port 88.
_kerberos-master._udp
This entry should refer to those KDCs, if any, that will immediately see password changes to the Kerberos database. This entry is used only in one case, when the user is logging in and the password appears to be incorrect; the master KDC is then contacted, and the same password used to try to decrypt the response, in case the user's password had recently been changed and the first KDC contacted hadn't been updated. Only if that fails is an “incorrect password” error given.

If you have only one KDC, or for whatever reason there is no accessible KDC that would get database changes faster than the others, you do not need to define this entry.

_kerberos-adm._tcp
This should list port 749 on your master KDC. Support for it is not complete at this time, but it will eventually be used by the kadmin program and related utilities. For now, you will also need the admin_server entry in krb5.conf. (See krb5.conf.)
_kpasswd._udp
This should list port 464 on your master KDC. It is used when a user changes her password.
_kerberos-iv._udp
This should refer to your KDCs that serve Kerberos version 4 requests, if you have Kerberos v4 enabled.

Be aware, however, that the DNS SRV specification requires that the hostnames listed be the canonical names, not aliases. So, for example, you might include the following records in your (BIND-style) zone file:

     $ORIGIN foobar.com.
     _kerberos               TXT       "FOOBAR.COM"
     kerberos                CNAME     daisy
     kerberos-1              CNAME     use-the-force-luke
     kerberos-2              CNAME     bunny-rabbit
     _kerberos._udp          SRV       0 0 88 daisy
                             SRV       0 0 88 use-the-force-luke
                             SRV       0 0 88 bunny-rabbit
     _kerberos-master._udp   SRV       0 0 88 daisy
     _kerberos-adm._tcp      SRV       0 0 749 daisy
     _kpasswd._udp           SRV       0 0 464 daisy

As with the DNS-based mechanism for determining the Kerberos realm of a host, we recommend distributing the information this way for use by other sites that may want to interact with yours using Kerberos, even if you don't immediately make use of it within your own site. If you anticipate installing a very large number of machines on which it will be hard to update the Kerberos configuration files, you may wish to do all of your Kerberos service lookups via DNS and not put the information (except for admin_server as noted above) in future versions of your krb5.conf files at all. Eventually, we hope to phase out the listing of server hostnames in the client-side configuration files; making preparations now will make the transition easier in the future.


Next: , Previous: Using DNS, Up: Top

5 Administrating the Kerberos Database

Your Kerberos database contains all of your realm's Kerberos principals, their passwords, and other administrative information about each principal. For the most part, you will use the kdb5_util program to manipulate the Kerberos database as a whole, and the kadmin program to make changes to the entries in the database. (One notable exception is that users will use the kpasswd program to change their own passwords.) The kadmin program has its own command-line interface, to which you type the database administrating commands.

Kdb5_util provides a means to create, delete, load, or dump a Kerberos database. It also includes a command to stash a copy of the master database key in a file on a KDC, so that the KDC can authenticate itself to the kadmind and krb5kdc daemons at boot time.

Kadmin provides for the maintenance of Kerberos principals, KADM5 policies, and service key tables (keytabs). It exists as both a Kerberos client, kadmin, using Kerberos authentication and an RPC, to operate securely from anywhere on the network, and as a local client, kadmin.local, intended to run directly on the KDC without Kerberos authentication. kadmin.local need not run on the kdc if the database is LDAP. Other than the fact that the remote client uses Kerberos to authenticate the person using it, the functionalities of the two versions are identical. The local version is necessary to enable you to set up enough of the database to be able to use the remote version. It replaces the now obsolete kdb5_edit (except for database dump and load, which are provided by kdb5_util).

The remote version authenticates to the KADM5 server using the service principal kadmin/admin. If the credentials cache contains a ticket for the kadmin/admin principal, and the -c ccache option is specified, that ticket is used to authenticate to KADM5. Otherwise, the -p and -k options are used to specify the client Kerberos principal name used to authenticate. Once kadmin has determined the principal name, it requests a kadmin/admin Kerberos service ticket from the KDC, and uses that service ticket to authenticate to KADM5.


Next: , Previous: Administrating the Kerberos Database, Up: Administrating the Kerberos Database

5.1 Kadmin Options

You can invoke kadmin or kadmin.local with any of the following options:

-r REALM
Use REALM as the default Kerberos realm for the database.
-p principal
Use the Kerberos principal principal to authenticate to Kerberos. If this option is not given, kadmin will append admin to either the primary principal name, the environment variable USER, or to the username obtained from getpwuid, in order of preference.
-q query
Pass query directly to kadmin. This is useful for writing scripts that pass specific queries to kadmin.

You can invoke kadmin with any of the following options:

-k [-t keytab]
Use the keytab keytab to decrypt the KDC response instead of prompting for a password on the TTY. In this case, the principal will be host/hostname. If -t is not used to specify a keytab, then the default keytab will be used.
-c credentials cache
Use credentials_cache as the credentials cache. The credentials cache should contain a service ticket for the kadmin/admin service, which can be acquired with the kinit program. If this option is not specified, kadmin requests a new service ticket from the KDC, and stores it in its own temporary ccache.
-w password
Use password as the password instead of prompting for one on the TTY. Note: placing the password for a Kerberos principal with administration access into a shell script can be dangerous if unauthorized users gain read access to the script.
-x db_args
Specifies the database specific arguments.
-x host=<hostname>
Specifies the LDAP server to connect to by a LDAP URI. It is recommend to use ldapi:// or ldaps:// interface to connect to the LDAP server.
-x binddn=<bind_dn>
Specifies the Distinguished Name (DN) of the object used by the administration server to bind to the LDAP server. This object should have the read and write rights on the realm container, principal container and realm subtree.
-x bindpwd=<bind_password>
Specifies the password for the above mentioned binddn. It is recommended not to use this option. Instead, the password can be stashed using the stashsrvpw command of kdb5_ldap_util.

Note: This database specific argument is applicable only to kadmin.local and the KADM5 server.

-s admin_server[:port]
Specifies the admin server that kadmin should contact.

You can invoke kadmin.local with an of the follwing options:

-d_ dbname
Specifies the name of the Kerberos database.
-e "enctypes ..."
Sets the list of cryptosystem and salt types to be used for any new keys created. See Supported Encryption Types and Salts for available types.
-m
Do not authenticate using a keytab. This option will cause kadmin to prompt for the master database password.


Next: , Previous: Kadmin Options, Up: Administrating the Kerberos Database

5.2 Date Format

Many of the kadmin commands take a duration or time as an argument. The date can appear in a wide variety of formats, such as:

     "15 minutes"
     "7 days"
     "1 month"
     "2 hours"
     "400000 seconds"
     "next year"
     "this Monday"
     "next Monday"
     yesterday
     tomorrow
     now
     "second Monday"
     fortnight
     "3/31/1992 10:00:07 PST"
     "January 23, 2007 10:05pm"
     "22:00 GMT"

Note that if the date specification contains spaces, you must enclose it in double quotes. Note also that you cannot use a number without a unit. (I.e., “"60 seconds"” is correct, but “60” is incorrect.) All keywords are case-insensitive. The following is a list of all of the allowable keywords.

Months
january, jan, february, feb, march, mar, april, apr, may, june, jun, july, jul, august, aug, september, sep, sept, october, oct, november, nov, december, dec
Days
sunday, sun, monday, mon, tuesday, tues, tue, wednesday, wednes, wed, thursday, thurs, thur, thu, friday, fri, saturday, sat
Units
year, month, fortnight, week, day, hour, minute, min, second, sec
Relative
tomorrow, yesterday, today, now, last, this, next, first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth, eleventh, twelfth, ago
Time Zones
kadmin recognizes abbreviations for most of the world's time zones. A complete listing appears in kadmin Time Zones.
12-hour Time Delimiters
am, pm


Next: , Previous: Date Format, Up: Administrating the Kerberos Database

5.3 Principals

Each entry in the Kerberos database contains a Kerberos principal (see Definitions) and the attributes and policies associated with that principal.


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5.3.1 Retrieving Information About a Principal


Next: , Previous: Retrieving Information About a Principal, Up: Retrieving Information About a Principal
5.3.1.1 Attributes

To retrieve a listing of the attributes and/or policies associated with a principal, use the kadmin get_principal command, which requires the “inquire” administrative privilege. The syntax is:

     get_principal principal

The get_principal command has the alias getprinc.

For example, suppose you wanted to view the attributes of the principal
jennifer/root@ATHENA.MIT.EDU. You would type:

     shell% kadmin
     kadmin: getprinc jennifer/root
     Principal: jennifer/root@ATHENA.MIT.EDU
     Expiration date: [never]
     Last password change: Mon Jan 31 02:06:40 EDT 2002
     Password Expiration date: [none]
     Maximum ticket life: 0 days 10:00:00
     Maximum renewable life: 7 days 00:00:00
     Last modified: Wed Jul 24 14:46:25 EDT 2002 (joeadmin/admin@ATHENA.MIT.EDU)
     Last successful authentication: Mon Jul 29 18:20:17 EDT 2002
     Last failed authentication: Mon Jul 29 18:18:54 EDT 2002
     Failed password attempts: 3
     Number of keys: 2
     Key: vno 2, Triple DES cbc mode with HMAC/sha1, no salt
     Key: vno 2, DES cbc mode with CRC-32, no salt
     Attributes: DISALLOW_FORWARDABLE, DISALLOW_PROXIABLE
     Policy: [none]
     kadmin:

The get_principal command has a -terse option, which lists the fields as a quoted, tab-separated string. For example:

     kadmin: getprinc -terse jennifer/root
     jennifer/root@ATHENA.MIT.EDU	0	1027458564
     0	36000	 (joeadmin/admin@ATHENA.MIT.EDU
     1027536385	18	2	0	[none]	604800	1027980137
     1027980054	3	2	1	2	16	0	1
     2	1	0
     kadmin:


Previous: Attributes, Up: Retrieving Information About a Principal
5.3.1.2 Retrieving a List of Principals

To generate a listing of principals, use the kadmin list_principals command, which requires the “list” privilege. The syntax is:

     list_principals [expression]

where expression is a shell-style glob expression that can contain the characters *, ?, [, and ]. All policy names matching the expression are displayed. The list_principals command has the aliases listprincs, get_principals, and getprincs. For example:

     kadmin: listprincs test*
     test3@ATHENA.MIT.EDU
     test2@ATHENA.MIT.EDU
     test1@ATHENA.MIT.EDU
     testuser@ATHENA.MIT.EDU
     kadmin:

If no expression is provided, all principals are printed.


Next: , Previous: Retrieving Information About a Principal, Up: Principals

5.3.2 Privileges

Administrative privileges for the Kerberos database are stored in the file kadm5.acl.

The format of the file is:

     Kerberos_principal      permissions     [target_principal]	[restrictions]

The Kerberos principal (and optional target principal) can include the “*” wildcard, so if you want any principal with the instance “admin” to have full permissions on the database, you could use the principal “*/admin@REALM” where “REALM” is your Kerberos realm. target_principal can also include backreferences to Kerberos_principal, in which "*number" matches the component number in the Kerberos_principal.

Note: a common use of an admin instance is so you can grant separate permissions (such as administrator access to the Kerberos database) to a separate Kerberos principal. For example, the user joeadmin might have a principal for his administrative use, called joeadmin/admin. This way, joeadmin would obtain joeadmin/admin tickets only when he actually needs to use those permissions.

The permissions are represented by single letters; UPPER-CASE letters represent negative permissions. The permissions are:

a
allows the addition of principals or policies in the database.
A
disallows the addition of principals or policies in the database.
d
allows the deletion of principals or policies in the database.
D
disallows the deletion of principals or policies in the database.
m
allows the modification of principals or policies in the database.
M
disallows the modification of principals or policies in the database.
c
allows the changing of passwords for principals in the database.
C
disallows the changing of passwords for principals in the database.
i
allows inquiries to the database.
I
disallows inquiries to the database.
l
allows the listing of principals or policies in the database.
L
disallows the listing of principals or policies in the database.
s
allows the explicit setting of the key for a principal
S
disallows the explicit setting of the key for a principal
*
All privileges (admcil).
x
All privileges (admcil); identical to “*”.

The restrictions are a string of flags. Allowed restrictions are:

[+ -]flagname
flag is forced to indicated value. The permissible flags are the same as the + and - flags for the kadmin addprinc and modprinc commands.
-clearpolicy
policy is forced to clear
-policy pol
policy is forced to be pol
expire time
pwexpire time
maxlife time
maxrenewlife time
associated value will be forced to MIN(time, requested value)

The above flags act as restrictions on any add or modify operation which is allowed due to that ACL line.

Here is an example of a kadm5.acl file. Note that order is important; permissions are determined by the first matching entry.

     */admin@ATHENA.MIT.EDU  *
     joeadmin@ATHENA.MIT.EDU  ADMCIL
     joeadmin/*@ATHENA.MIT.EDU il */root@ATHENA.MIT.EDU
     *@ATHENA.MIT.EDU cil *1/admin@ATHENA.MIT.EDU
     */*@ATHENA.MIT.EDU  i
     */admin@EXAMPLE.COM * -maxlife 9h -postdateable

In the above file, any principal in the ATHENA.MIT.EDU realm with an admin instance has all administrative privileges. The user joeadmin has all permissions with his admin instance, joeadmin/admin@ATHENA.MIT.EDU (matches the first line). He has no permissions at all with his null instance, joeadmin@ATHENA.MIT.EDU (matches the second line). His root instance has inquire and list permissions with any other principal that has the instance root. Any principal in ATHENA.MIT.EDU can inquire, list, or change the password of their admin instance, but not any other admin instance. Any principal in the realm ATHENA.MIT.EDU (except for joeadmin@ATHENA.MIT.EDU, as mentioned above) has inquire privileges. Finally, any principal with an admin instance in EXAMPLE.COM has all permissions, but any principal that they create or modify will not be able to get postdateable tickets or tickets with a life of longer than 9 hours.


Next: , Previous: Privileges, Up: Principals

5.3.3 Adding or Modifying Principals

To add a principal to the database, use the kadmin add_principal command, which requires the “add” administrative privilege. This function creates the new principal, prompting twice for a password, and, if neither the -policy nor -clearpolicy options are specified and the policy “default” exists, assigns it that policy. The syntax is:

     kadmin: add_principal [options] principal

To modify attributes of a principal, use the kadmin modify_principal command, which requires the “modify” administrative privilege. The syntax is:

     kadmin: modify_principal [options] principal

add_principal has the aliases addprinc and ank2. modify_principal has the alias modprinc.

The add_principal and modify_principal commands take the following switches:

-x db_princ_args
Denotes the database specific options. The options for LDAP database are:
-x dn=<dn>
Specifies the LDAP object that will contain the Kerberos principal being created.
-x linkdn=<dn>
Specifies the LDAP object to which the newly created Kerberos principal object will point to.
-x containerdn=<container_dn>
Specifies the container object under which the Kerberos principal is to be created.
-x tktpolicy=<policy>
Associates a ticket policy to the Kerberos principal. Specifying an empty string value clears the ticket policy associated with the principal. Note: * dn and containerdn options are not valid while modifying the principal. * containerdn and linkdn options cannot be specified with dn option. * If dn or containerdn options are not specified while adding the principal, the principals are created under the prinicipal container configured in the realm or the realm container. * dn and containerdn should be within the subtrees or principal container configured in the realm.

-expire date
Sets the expiration date of the principal to date.
-pwexpire date
Sets the expiration date of the password to date.
-maxlife maxlife
Sets the maximum ticket life of the principal to maxlife.
-maxrenewlife maxrenewlife
Sets the maximum renewable life of tickets for the principal to maxrenewlife.
-kvno number
Explicity sets the key version number to number. MIT does not recommend doing this unless there is a specific reason.
-policy policy
Sets the policy used by this principal. (See Policies.) With modify_principal, the current policy assigned to the principal is set or changed. With add_principal, if this option is not supplied, the -clearpolicy is not specified, and the policy “default” exists, that policy is assigned. If a principal is created with no policy, kadmin will print a warning message.
-clearpolicy
For modify_principal, removes the current policy from a principal. For add_principal, suppresses the automatic assignment of the policy “default”.
{-|+}allow_postdated
The “-allow_postdated” option prohibits this principal from obtaining postdated tickets. “+allow_postdated” clears this flag. In effect, “-allow_postdated” sets the KRB5_KDB_DISALLOW_POSTDATED flag on the principal in the database.
{-|+}allow_forwardable
The “-allow_forwardable” option prohibits this principal from obtaining forwardable tickets. “+allow_forwardable” clears this flag. In effect, “-allow_forwardable” sets the KRB5_KDB_DISALLOW_FORWARDABLE flag on the principal in the database.
{-|+}allow_renewable
The “-allow_renewable” option prohibits this principal from obtaining renewable tickets. “+allow_renewable” clears this flag. In effect, “-allow_renewable” sets the KRB5_KDB_DISALLOW_RENEWABLE flag on the principal in the database.
{-|+}allow_proxiable
The “-allow_proxiable” option prohibits this principal from obtaining proxiable tickets. “+allow_proxiable” clears this flag. In effect, “-allow_proxiable” sets the
KRB5_KDB_DISALLOW_PROXIABLE flag. on the principal in the database.
{-|+}allow_dup_skey
The “-allow_dup_skey” option disables user-to-user authentication for this principal by prohibiting this principal from obtaining a session key for another user. “+allow_dup_skey” clears this flag. In effect, “-allow_dup_skey” sets the
KRB5_KDB_DISALLOW_DUP_SKEY flag on the principal in the database.
{-|+}requires_preauth
The “+requires_preauth” option requires this principal to preauthenticate before being allowed to kinit. -requires_preauth clears this flag. In effect, +requires_preauth sets the KRB5_KDB_REQUIRES_PRE_AUTH flag on the principal in the database.
{-|+}requires_hwauth
The “+requires_hwauth” flag requires the principal to preauthenticate using a hardware device before being allowed to kinit. “-requires_hwauth” clears this flag. In effect, “+requires_hwauth” sets the KRB5_KDB_REQUIRES_HW_AUTH flag on the principal in the database.
{-|+}allow_svr
The “-allow_svr” flag prohibits the issuance of service tickets for this principal. “+allow_svr” clears this flag. In effect, “-allow_svr” sets the
KRB5_KDB_DISALLOW_SVR flag on the principal in the database.
{-|+}allow_tgs_req
The “-allow_tgs_req” option specifies that a Ticket-Granting Service (TGS) request for a service ticket for this principal is not permitted. You will probably never need to use this option. “+allow_tgs_req” clears this flag. The default is “+allow_tgs_req”. In effect, “-allow_tgs_req” sets the KRB5_KDB_DISALLOW_TGT_BASED flag on the principal in the database.
{-|+}allow_tix
The “-allow_tix” option forbids the issuance of any tickets for this principal. “+allow_tix” clears this flag. The default is “+allow_tix”. In effect, “-allow_tix” sets the
KRB5_KDB_DISALLOW_ALL_TIX flag on the principal in the database.
{-|+}needchange
The “+needchange” option sets a flag in attributes field to force a password change; “-needchange” clears it. The default is “-needchange”. In effect, “+needchange” sets the KRB5_KDB_REQUIRES_PWCHANGE flag on the principal in the database.
{-|+}password_changing_service
The “+password_changing_service” option sets a flag in the attributes field marking this principal as a password change service. (Again, you will probably never need to use this option.) “-password_changing_service” clears the flag. The default is “-password_changing_service”. In effect, the “+password_changing_service” option sets the KRB5_KDB_PWCHANGE_SERVICE flag on the principal in the database.
-randkey
Sets the key for the principal to a random value (add_principal only). MIT recommends using this option for host keys.
-pw password
Sets the key of the principal to the specified string and does not prompt for a password (add_principal only). MIT does not recommend using this option.
-e enc:salt...
Uses the specified list of enctype-salttype pairs for setting the key of the principal. The quotes are necessary if there are multiple enctype-salttype pairs. This will not function against kadmin daemons earlier than krb5-1.2. See Supported Encryption Types and Salts for available types.

If you want to just use the default values, all you need to do is:

     kadmin: addprinc jennifer
     WARNING: no policy specified for "jennifer@ATHENA.MIT.EDU";
     defaulting to no policy.
     Enter password for principal jennifer@ATHENA.MIT.EDU:  <= Type the password.
     Re-enter password for principal jennifer@ATHENA.MIT.EDU:  <=Type it again.
     Principal "jennifer@ATHENA.MIT.EDU" created.
     kadmin:

If you want to create a principal which is contained by a LDAP object, all you need to do is:

     kadmin: addprinc -x dn=cn=jennifer,o=mit jennifer
     WARNING: no policy specified for "jennifer@ATHENA.MIT.EDU";
     defaulting to no policy.
     Enter password for principal jennifer@ATHENA.MIT.EDU:  <= Type the password.
     Re-enter password for principal jennifer@ATHENA.MIT.EDU:  <=Type it again.
     Principal "jennifer@ATHENA.MIT.EDU" created.
     kadmin:

If you want to create a principal under a specific LDAP container and link to an existing LDAP object, all you need to do is:

     kadmin: addprinc -x containerdn=o=mit -x linkdn=cn=david,o=mit david
     WARNING: no policy specified for "david@ATHENA.MIT.EDU";
     defaulting to no policy.
     Enter password for principal david@ATHENA.MIT.EDU:  <= Type the password.
     Re-enter password for principal david@ATHENA.MIT.EDU:  <=Type it again.
     Principal "david@ATHENA.MIT.EDU" created.
     kadmin:

If you want to associate a ticket policy to a principal, all you need to do is:

     kadmin: modprinc -x tktpolicy=userpolicy david
     Principal "david@ATHENA.MIT.EDU" modified.
     kadmin:

If, on the other hand, you want to set up an account that expires on January 1, 2000, that uses a policy called “stduser”, with a temporary password (which you want the user to change immediately), you would type the following. (Note: each line beginning with => is a continuation of the previous line.)

     
     kadmin: addprinc david -expire "1/1/2000 12:01am EST" -policy stduser
     =>  +needchange
     Enter password for principal david@ATHENA.MIT.EDU:  <= Type the password.
     Re-enter password for principal
     david@ATHENA.MIT.EDU:  <= Type it again.
     Principal "david@ATHENA.MIT.EDU" created.
     kadmin:

If you will need cross-realm authentication, you need to add principals for the other realm's TGT to each realm. For example, if you need to do cross-realm authentication between the realms ATHENA.MIT.EDU and EXAMPLE.COM, you would need to add the principals
krbtgt/EXAMPLE.COM@ATHENA.MIT.EDU and krbtgt/ATHENA.MIT.EDU@EXAMPLE.COM to both databases. You need to be sure the passwords and the key version numbers (kvno) are the same in both databases. This may require explicitly setting the kvno with the -kvno option. See Cross-realm Authentication for more details.


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5.3.4 Deleting Principals

To delete a principal, use the kadmin delete_principal command, which requires the “delete” administrative privilege. The syntax is:

     delete_principal [-force] principal

delete_principal has the alias delprinc. The -force option causes delete_principal not to ask if you're sure. For example:

     kadmin: delprinc jennifer
     Are you sure you want to delete the principal
     "jennifer@ATHENA.MIT.EDU"? (yes/no): yes
     Principal "jennifer@ATHENA.MIT.EDU" deleted.
     Make sure that you have removed this principal from
     all ACLs before reusing.
     kadmin:


Previous: Deleting Principals, Up: Principals

5.3.5 Changing Passwords

To change a principal's password use the kadmin change_password command, which requires the “modify” administrative privilege (unless the principal is changing his/her own password). The syntax is:

     change_password [options] principal

The change_password option has the alias cpw. change_password takes the following options:

-randkey
Sets the key of the principal to a random value.
-pw password
Sets the password to the string password. MIT does not recommend using this option.
-e "enc:salt..."
Uses the specified list of enctype-salttype pairs for setting the key of the principal. The quotes are necessary if there are multiple enctype-salttype pairs. This will not function against kadmin daemons earlier than krb5-1.2. See Supported Encryption Types and Salts for possible values.
-keepold
Keeps the previous kvno's keys around. There is no easy way to delete the old keys, and this flag is usually not necessary except perhaps for TGS keys. Don't use this flag unless you know what you're doing. This option is not supported for the LDAP database

For example:

     kadmin: cpw david
     Enter password for principal david@ATHENA.MIT.EDU:  <= Type the new password.
     Re-enter password for principal david@ATHENA.MIT.EDU:  <= Type it again.
     Password for david@ATHENA.MIT.EDU changed.
     kadmin:

Note that change_password will not let you change the password to one that is in the principal's password history.


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5.4 Policies

A policy is a set of rules governing passwords. Policies can dictate minimum and maximum password lifetimes, minimum number of characters and character classes a password must contain, and the number of old passwords kept in the database.


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5.4.1 Retrieving Policies

To retrieve a policy, use the kadmin get_policy command, which requires the “inquire” administrative privilege. The syntax is:

     get_policy [-terse] policy

The get_policy command has the alias getpol. For example:

     kadmin: get_policy admin
     Policy: admin
     Maximum password life: 180 days 00:00:00
     Minimum password life: 00:00:00
     Minimum password length: 6
     Minimum number of password character classes: 2
     Number of old keys kept: 5
     Reference count: 17
     kadmin:

The reference count is the number of principals using that policy.

The get_policy command has a -terse option, which lists each field as a quoted, tab-separated string. For example:

     kadmin: get_policy -terse admin
     admin   15552000        0       6       2       5       17
     kadmin:


Next: , Previous: Retrieving Policies, Up: Policies

5.4.2 Retrieving the List of Policies

You can retrieve the list of policies with the kadmin list_policies command, which requires the “list” privilege. The syntax is:

     list_policies [expression]

where expression is a shell-style glob expression that can contain the characters *, ?, and []. All policy names matching the expression are displayed. The list_policies command has the aliases listpols, get_policies, and getpols. For example:

     kadmin:  listpols
     test-pol
     dict-only
     once-a-min
     test-pol-nopw
     
     kadmin:  listpols t*
     test-pol
     test-pol-nopw
     kadmin:


Next: , Previous: Retrieving the List of Policies, Up: Policies

5.4.3 Adding or Modifying Policies

To add a new policy, use the kadmin add_policy command, which requires the “add” administrative privilege. The syntax is:

     add_policy [options] policy_name

To modify attributes of a principal, use the kadmin modify_policy command, which requires the “modify” administrative privilege. The syntax is:

     modify_policy [options] policy_name

add_policy has the alias addpol. modify_poilcy has the alias modpol.

The add_policy and modify_policy commands take the following switches:

-maxlife time
Sets the maximum lifetime of a password to time.
-minlife time
Sets the minimum lifetime of a password to time.
-minlength length
Sets the minimum length of a password to length characters.
-minclasses number
Requires at least number of character classes in a password.
-history number
Sets the number of past keys kept for a principal to number. This option is not supported for LDAP database.

Note: The policies are created under realm container in the LDAP database.


Previous: Adding or Modifying Policies, Up: Policies

5.4.4 Deleting Policies

To delete a policy, use the kadmin delete_policy command, which requires the “delete” administrative privilege. The syntax is:

     delete_policy [-force] policy_name

The delete_policy command has the alias delpol. It prompts for confirmation before deletion. For example:

     kadmin: delete_policy guests
     Are you sure you want to delete the policy "guests"?
     (yes/no): yes
     kadmin:

Note that you must cancel the policy from all principals before deleting it. The delete_policy command will fail if it is in use by any principals.


Next: , Previous: Policies, Up: Administrating the Kerberos Database

5.5 Global Operations on the Kerberos Database

The kdb5_util command is the primary tool for administrating the Kerberos database. The syntax is:

     kdb5_util command [kdb5_util_options] [command_options]

The kdb5_util command takes the following options, which override the defaults specified in the configuration files:

-r realm
specifies the the Kerberos realm of the database.
-d database_name
specifies the name under which the principal database is stored.
-k master_key_type
specifies the key type of the master key in the database.
-M master_key_name
specifies the principal name of the master key in the database.
-m
indicates that the master database password should be read from the TTY rather than fetched from a file on disk.
-sf stash_file
specifies the stash file of the master database password
-P password
specifies the master database password. MIT does not recommend using this option.


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5.5.1 Dumping a Kerberos Database to a File

To dump a Kerberos database into a file, use the kdb5_util dump command on one of the KDCs. The syntax is:

     kdb5_util dump [-old] [-b6] [-b7] [-ov]
     [-verbose] [-mkey_convert] [-new_mkey_file] [filename
     [principals...]]

The kdb5_util dump command takes the following options:

-old
causes the dump to be in the Kerberos 5 Beta 5 and earlier dump format (“kdb5_edit load_dump version 2.0”).
-b6
causes the dump to be in the Kerberos 5 Beta 6 format (“kdb5_edit load_dump version 3.0”).
-b7
causes the dump to be in the Kerberos 5 Beta 7 format (“kdbt_edit load_dump version 4”).
-ov
causes the dump to be in ovsec_adm_export format. Currently, the only way to preserve per-principal policy information is to use this in conjunction with a normal dump.
-verbose
causes the name of each principal and policy to be printed as it is dumped.
-mkey_convert
prompts for a new master password, and then dumps the database with all keys reencrypted in this new master key
-new_mkey_file
reads a new key from the default keytab and then dumps the database with all keys reencrypted in this new master key

For example:

     shell% kdb5_util dump dumpfile
     shell%
     shell% kbd5_util dump -verbose dumpfile
     kadmin/admin@ATHENA.MIT.EDU
     krbtgt/ATHENA.MIT.EDU@ATHENA.MIT.EDU
     kadmin/history@ATHENA.MIT.EDU
     K/M@ATHENA.MIT.EDU
     kadmin/changepw@ATHENA.MIT.EDU
     shell%

If you specify which principals to dump, you must use the full principal, as in the following example. (The line beginning with => is a continuation of the previous line.):

     shell% kdb5_util dump -verbose dumpfile K/M@ATHENA.MIT.EDU
     => kadmin/admin@ATHENA.MIT.EDU
     kadmin/admin@ATHENA.MIT.EDU
     K/M@ATHENA.MIT.EDU
     shell%

Otherwise, the principals will not match those in the database and will not be dumped:

     shell% kdb5_util dump -verbose dumpfile K/M kadmin/admin
     shell%

If you do not specify a dump file, kdb5_util will dump the database to the standard output.

There is currently a bug where the default dump format omits the per-principal policy information. In order to dump all the data contained in the Kerberos database, you must perform a normal dump (with no option flags) and an additional dump using the “-ov” flag to a different file.


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5.5.2 Restoring a Kerberos Database from a Dump File

To restore a Kerberos database dump from a file, use the kdb5_util load command on one of the KDCs. The syntax is:

     kdb5_util load [-old] [-b6] [-b7] [-ov] [-verbose]
     [-update] [-hash] dumpfilename dbname [admin_dbname]

The kdb5_util load command takes the following options:

-old
requires the dump to be in the Kerberos 5 Beta 5 and earlier dump format (“kdb5_edit load_dump version 2.0”).
-b6
requires the dump to be in the Kerberos 5 Beta 6 format (“kdb5_edit load_dump version 3.0”).
-b7
requires the dump to be in the Kerberos 5 Beta 7 format (“kdb5_edit load_dump version 4”).
-ov
requires the dump to be in ovsec_adm_export format.
-verbose
causes the name of each principal and policy to be printed as it is loaded.
-update
causes records from the dump file to be updated in or added to the existing database. This is useful in conjunction with an ovsec_adm_export format dump if you want to preserve per-principal policy information, since the current default format does not contain this data.
-hash
causes the database to be stored as a hash rather than a binary tree.

For example:

     shell% kdb5_util load dumpfile principal
     shell%
     shell% kdb5_util load -update dumpfile principal
     shell%

If the database file exists, and the -update flag was not given, kdb5_util will overwrite the existing database.


Next: , Previous: Restoring a Kerberos Database from a Dump File, Up: Global Operations on the Kerberos Database

5.5.3 Creating a Stash File

A stash file allows a KDC to authenticate itself to the database utilities, such as kadmin, kadmind, krb5kdc, and kdb5_util.

To create a stash file, use the kdb5_util stash command. The syntax is:

     kdb5_util stash [-f keyfile]

For example:

     shell% kdb5_util stash
     kdb5_util: Cannot find/read stored master key while reading master key
     kdb5_util: Warning: proceeding without master key
     Enter KDC database master key:  <= Type the KDC database master password.
     shell%

If you do not specify a stash file, kdb5_util will stash the key in the file specified in your kdc.conf file.


Previous: Creating a Stash File, Up: Global Operations on the Kerberos Database

5.5.4 Creating and Destroying a Kerberos Database

If you need to create a new Kerberos database, use the kdb5_util create command. The syntax is:

     kdb5_util create [-s]

If you specify the -s option, kdb5_util will stash a copy of the master key in a stash file. (See Creating a Stash File.) For example:

     shell% /usr/local/sbin/kdb5_util -r ATHENA.MIT.EDU create -s
     kdb5_util: No such file or directory while setting active database to
     => '/usr/local/var/krb5kdc/principal'
     Initializing database '/usr/local/var/krb5kdc/principal' for
     => realm 'ATHENA.MIT.EDU',
     master key name 'K/M@ATHENA.MIT.EDU'
     You will be prompted for the database Master Password.
     It is important that you NOT FORGET this password.
     Enter KDC database master key:  <= Type the master password.
     Re-enter KDC database master key to verify:  <= Type it again.
     shell%

If you need to destroy the current Kerberos database, use the kdb5_util destroy command. The syntax is:

     kdb5_util destroy [-f]

The destroy command destroys the database, first overwriting the disk sectors and then unlinking the files. If you specify the -f option, kdb5_util will not prompt you for a confirmation before destroying the database.

     shell% /usr/local/sbin/kdb5_util -r ATHENA.MIT.EDU destroy
     kdb5_util: Deleting KDC database stored in /usr/local/var/krb5kdc/principal, are you sure
     (type yes to confirm)? <== yes
     OK, deleting database '/usr/local/var/krb5kdc/principal'...
     
     shell%


Next: , Previous: Global Operations on the Kerberos Database, Up: Administrating the Kerberos Database

5.6 Global Operations on the Kerberos LDAP Database

The kdb5_ldap_util is the primary tool for administrating the Kerberos LDAP database. It allows an administrator to manage realms, Kerberos services ( KDC and Admin Server) and ticket policies. The syntax is:

     kdb5_ldap_util [-D user_dn [-w passwd]] [-H ldap_uri] command [command_options]
-D user_dn
Specifies the Distinguished Name (DN) of the user who has sufficient rights to perform the operation on the LDAP server.
-w passwd
Specifies the password of user_dn. This option is not recommended.
-H ldap_uri
Specifies the URI of the LDAP server. It is recommended to use ldapi:// or ldaps:// to connect to the LDAP server.


Next: , Previous: Global Operations on the Kerberos LDAP Database, Up: Global Operations on the Kerberos LDAP Database

5.6.1 Creating a Kerberos Realm

If you need to create a new realm, use the command as follows:

     
     create  [-r realm]  [-subtrees subtree_dn_list] [-sscope search_scope] [-containerref container_reference_dn]
     [-k  mkeytype] [-m|-P password][-sf stashlename] [-s] [-maxtktlife max_ticket_life]
     [-maxrenewlife  max_renewable_ticket_life] [ticket_flags]
     

Options to create realm in directory are as follows:

-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm (3) is used.
-subtrees subtree_dn_list
Specifies the list of subtrees containing principals of a realm. The list contains the DN of the subtree objects separated by colon(:).
-sscope search_scope
Specifies the scope for searching the principals under the subtree. The possible values are 1 or one (one level), 2 or sub (subtree).
-containerref container_reference_dn
Specfies the DN of the container object in which the principals of a realm will be created. If the container reference is not configured for a realm, the principals will be created in the realm container.
-k mkeytype
Specifies the key type of the master key in the database; the default is that given in kdc.conf.
-m
Specifies that the master database password should be read from the TTY rather than fetched from a file on disk.
-p password
Specifies the master database password. This option is not recommended.
-sf stashfilename
Specifies the stash file of the master database password.
-s
Specifies that the stash file is to be created.
-maxtktlife max_ticket_life
Specifies maximum ticket life for principals in this realm. This value is used, if it is not set on the principal.
-maxrenewlife max_renewable_ticket_life
Specifies maximum renewable life of tickets for principals in this realm. This value is used, if it is not set on the principal.
ticket_flags
Specifies the ticket flags. If this option is not specified, by default, none of the flags are set. This means all the ticket options will be allowed and no restriction will be set. This value is used, if it is not set on the principal. The various flags are:
{-|+}allow_postdated
-allow_postdated prohibits principals from obtaining postdated tickets. (Sets the KRB5_KDB_DISALLOW_POSTDATED flag.).+allow_postdated clears this flag.
{-|+}allow_forwardable
-allow_forwardable prohibits principals from obtaining forwardable tickets. (Sets the KRB5_KDB_DISALLOW_FORWARDABLE flag.) +allow_forwardable clears this flag.
{-|+}allow_renewable
-allow_renewable prohibits principals from obtaining renewable tickets. (Sets the KRB5_KDB_DISALLOW_RENEWABLE flag.) +allow_renewable clears this flag.
{-|+}allow_proxiable
-allow_proxiable prohibits principals from obtaining proxiable tickets. (Sets the KRB5_KDB_DISALLOW_PROXABLE flag.) +allow_proxiable clears this flag.
{-|+}allow_dup_skey
-allow_dup_skey disables user-to-user authentication for principals by prohibiting principals from obtaining a sessions key for another user. (Sets the KRB5_KDB_DISALLOW_DUP_SKEY flag.) +allow_dup_skey clears this flag.
{-|+}requires_preauth
+requires_preauth requires principals to preauthenticate before being allowed to kinit. (Sets the KRB5_KDB_REQURES_PRE_AUTH flag.) -requires_preauth clears this flag.
{-|+}requires_hwauth
+requires_hwauth requires principals to preauthenticate using a hardware device before being allowed to kinit. (Sets the KRB5_KDB_REQURES_HW_AUTH flag.) -requires_hwauth clears this flag.
{-|+}allow_svr
-allow_svr prohibits the issuance of service tickets for principals. (Sets the KRB5_KDB_DISALLOW_SVR flag.) +allow_svr clears this flag.
{-|+}allow_tgs_req
-allow_tgs_req specifies that a Ticket-Granting Service (TGS) request for a service ticket for principals is not permitted. This option is useless for most things.+allow_tgs_req clears this flag. The default is +allow_tgs_req. In effect, -allow_tgs_req sets the KRB5_KDB_DISALLOW_TGT_BASED flag on principals in the database.
{-|+}allow_tix
-allow_tix forbids the issuance of any tickets for principals. +allow_tix clears this flag. The default is +allow_tix. In effect, -allow_tix sets the KRB5_KDB_DISALLOW_ALL_TIX flag on principals in the database.
{-|+}needchange
+needchange sets a flag in attributes field to force a password change; -needchange clears it. The default is -needchange. In effect, +needchange sets the KRB5_KDB_REQURES_PWCHANGE flag on principals in the database.
{-|+}password_changing_service
+password_changing_service sets a flag in the attributes field marking principal as a password change service principal (useless for most things). -password_changing_service clears the flag. This flag intentionally has a long name. The default is -password_changing_service. In effect, +password_changing_service sets the KRB5_KDB_PWCHANGE_SERVICE flag on principals in the database.
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu create -sscope
     -subtree ou=users,o=org -r ATHENA.MIT.EDU
     Password for "cn=admin,o=org":
     Initializing database for realm 'ATHENA.MIT.EDU'
     You will be prompted for the database Master Password.
     It is important that you NOT FORGET this password.
     Enter KDC database master key:
     Re-enter KDC database master key to verify:
     shell%


Previous: Creating a Kerberos Realm, Up: Creating a Kerberos Realm
5.6.1.1 eDirectory Options
-kdcdn kdc_servce_list
Specifies the list of KDC service objects serving the realm. The list contains the DNs of the KDC service objects separated by colon(:).
-admindn admin_service_list
Specifies the list of Administration service objects serving the realm. The list contains the DNs of the Administration service objects separated by colon(:).
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu create -sscope
     -subtree ou=users,o=org -kdcdn cn=krbkdc,o=org -admindn cn=krbadmin,o=org -r ATHENA.MIT.EDU
     Password for "cn=admin,o=org":
     Initializing database for realm 'ATHENA.MIT.EDU'
     You will be prompted for the database Master Password.
     It is important that you NOT FORGET this password.
     Enter KDC database master key:
     Re-enter KDC database master key to verify:
     shell%


Next: , Previous: Creating a Kerberos Realm, Up: Global Operations on the Kerberos LDAP Database

5.6.2 Modifying a Kerberos Realm

If you need to modify a realm, use the command as follows:

     
     modify  [-r realm] [-subtrees subtree_dn] [-sscope search_scope][-containerref container_reference_dn]
     [-maxtktlifemax_ticket_life][-maxrenewlife max_renewable_ticket_life] [-ticket_flags]
     

Options to modify realm in directory are as follows:

-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm (3) is used.
-subtrees subtree_dn_list
Specifies the list of subtrees containing principal objects in the realm.The list contains the DN of the subtree objects separated by colon(:). This list replaces the existing list.
-sscope search_scope
Specifies the scope for searching the principals under the subtrees. The possible values are 1 or one (one level), 2 or sub (subtrees).
-containerref container_reference_dn
Specifies the Distinguished Name (DN) of the container object in which the principals of a realm will be created.
-maxtktlife max_ticket_life
Specifies maximum ticket life for principals in this realm. This value is used, if it is not set on the principal.
-maxrenewlife max_renewable_ticket_life
Specifies maximum renewable life of tickets for principals in this realm. This value is used, if it is not set on the principal.
-ticket_flags
Specifies the ticket flags. If this option is not specified, by default, none of the flags are set. This means all the ticket options will be allowed and no restriction will be set. This value is used, if it is not set on the principal. The various flags are:
{-|+}allow_postdated
-allow_postdated prohibits principals from obtaining postdated tickets. (Sets the KRB5_KDB_DISALLOW_POSTDATED flag.).+allow_postdated clears this flag.
{-|+}allow_forwardable
-allow_forwardable prohibits principals from obtaining forwardable tickets. (Sets the KRB5_KDB_DISALLOW_FORWARDABLE flag.) +allow_forwardable clears this flag.
{-|+}allow_renewable
-allow_renewable prohibits principals from obtaining renewable tickets. (Sets the KRB5_KDB_DISALLOW_RENEWABLE flag.) +allow_renewable clears this flag.
{-|+}allow_proxiable
-allow_proxiable prohibits principals from obtaining proxiable tickets. (Sets the KRB5_KDB_DISALLOW_PROXABLE flag.) +allow_proxiable clears this flag.
{-|+}allow_dup_skey
-allow_dup_skey Disables user-to-user authentication for principals by prohibiting principals from obtaining a sessions key for another user. (Sets the KRB5_KDB_DISALLOW_DUP_SKEY flag.). +allow_dup_skey clears This flag.
{-|+}requires_preauth
+requires_preauth requires principals to preauthenticate before being allowed to kinit. Sets the KRB5_KDB_REQURES_PRE_AUTH flag.-requires_preauth clears this flag.
{-|+}requires_hwauth
+requires_hwauth requires principals to preauthenticate using a hardware device before being allowed to kinit. (Sets the KRB5_KDB_REQURES_HW_AUTH flag.)-requires_hwauth clears this flag.
{-|+}allow_svr
-allow_svr prohibits the issuance of service tickets for principals. (Sets the KRB5_KDB_DISALLOW_SVR flag.) +allow_svr clears This flag.
{-|+}allow_tgs_req
-allow_tgs_req specifies that a Ticket-Granting Service (TGS) request for a service ticket for principals is not permitted. This option is useless for most things.+allow_tgs_req clears this flag. The default is. +allow_tgs_req. In effect, -allow_tgs_req sets the KRB5_KDB_DISALLOW_TGT_BASED flag on principals in the database.
{-|+}allow_tix
-allow_tix forbids the issuance of any tickets for principals. +allow_tix clears this flag. The default is +allow_tix. In effect, -allow_tix sets the KRB5_KDB_DISALLOW_ALL_TIX flag on principals in the database.
{-|+}needchange
+needchange sets a flag in attributes field to force a password change; -needchange clears it. The default is -needchange. In effect,+needchange sets the KRB5_KDB_REQURES_PWCHANGE flag on principals in the database.
{-|+}password_changing_service
+password_changing_service sets a flag in the attributes field marking principal as a password change service principal (useless for most things).-password_changing_service clears the flag. This flag intentionally has a long name. The default is -password_changing_service In effect, +password_changing_service sets the KRB5_KDB_PWCHANGE_SERVICE flag on principals in the database.

For example:

          shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
          modify -r ATHENA.MIT.EDU +requires_preauth
          Password for "cn=admin,o=org":
          shell%
     


Previous: Modifying a Kerberos Realm, Up: Modifying a Kerberos Realm
5.6.2.1 eDirectory Options
-kdcdn kdc_service_list
Specifies the list of KDC service objects serving the realm. The list contains the DNs of the KDC service objects separated by a colon (:). This list replaces the existing list.
-clearkdcdn kdc_service_list
Specifies the list of KDC service objects that need to be removed from the existing list. The list contains the DNs of the KDC service objects separated by a colon (:).
-addkdcdn kdc_service_list
Specifies the list of KDC service objects that need to be added to the existing list. The list contains the DNs of the KDC service objects separated by a colon (:).
-admindn admin_service_list
Specifies the list of Administration service objects serving the realm. The list contains the DNs of the Administration service objects separated by a colon (:). This list replaces the existing list.
-clearadmindn admin_service_list
Specifies the list of Administration service objects that need to be removed from the existing list. The list contains the DNs of the Administration service objects separated by a colon (:).
-addadmindn admin_service_list
Specifies the list of Administration service objects that need to be added to the existing list. The list contains the DNs of the Administration service objects separated by a colon (:).


Next: , Previous: Modifying a Kerberos Realm, Up: Global Operations on the Kerberos LDAP Database

5.6.3 Retrieving Information about a Kerberos Realm

view [-r realm]
Displays the attributes of a realm. Option is as follows:
-r realm
specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm (3)is used.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu view -r ATHENA.MIT.EDU
     Password for "cn=admin,o=org":
     Realm Name: ATHENA.MIT.EDU
     Subtree: ou=users,o=org
     Subtree: ou=servers,o=org
     SearchScope: ONE
     Maximum ticket life: 0 days 01:00:00
     Maximum renewable life: 0 days 10:00:00
     Ticket flags: DISALLOW_FORWARDABLE
     shell%


Next: , Previous: Retrieving Information about a Kerberos Realm, Up: Global Operations on the Kerberos LDAP Database

5.6.4 Destroying a Kerberos Realm

destroy [-f] [-r realm]
Destroys an existing realm. Options are as follows:
-f
If specified, will not prompt the user for confirmation.
-r realm
specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm (3)is used.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldap-server1.mit.edu destroy -r ATHENA.MIT.EDU
     Password for "cn=admin,o=org":
     Deleting KDC database of 'ATHENA.MIT.EDU', are you sure?
     type 'yes' to confirm)? Yes
     OK, deleting database of 'ATHENA.MIT.EDU'...
     shell%


Next: , Previous: Destroying a Kerberos Realm, Up: Global Operations on the Kerberos LDAP Database

5.6.5 Listing available Kerberos Realms

list
This option lists the name of the realms.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu list
     Password for "cn=admin,o=org":
     ATHENA.MIT.EDU
     OPENLDAP.MIT.EDU
     MEDIA-LAB.MIT.EDU
     shell%


Next: , Previous: Listing available Kerberos Realms, Up: Global Operations on the Kerberos LDAP Database

5.6.6 Stashing Service Object's Password

stashsrvpw [-f filename] servicedn

This command allows an administrator to store the password of service object in a file. The KDC and Administration server uses this password to authenticate to the LDAP server. Options are as follows:

-f filename
Specifies the complete path of the service password file. By default, /usr/local/var/service_passwd is used.
servicedn
Specifies the Distinguished Name (DN) of the service object whose password is to be stored in file.
For example:
     shell% kdb5_ldap_util stashsrvpw -f /home/andrew/conf_keyle cn=service-kdc,o=org
     Password for "cn=service-kdc,o=org":
     Re-enter password for "cn=service-kdc,o=org":
     shell%


Next: , Previous: Stashing Service Object's Password, Up: Global Operations on the Kerberos LDAP Database

5.6.7 Creating and Modifying a Ticket Policy

This command creates a ticket policy in directory.

     create_policy [-r realm] [-maxrenewlife max_renewable_ticket_life] [ticket_flags] policy_name

Ticket policy objects are created under the realm container.

This command modifies a ticket policy in directory.

     modify_policy [-r realm] [-maxrenewlife max_renewable_ticket_life] [ticket_flags] policy_name

Options are as follows:

-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm(3) is used.
-maxtktlife max_ticket_life
specifies maximum ticket life for principals.
-maxrenewlife max_renewable_ticket_life
specifies maximum renewable life of tickets for principals.
ticket_flags
Specifies the ticket flags. If this option is not specified, by default, none of the flags are set. This means all the ticket options will be allowed and no restriction will be set.

The various flags are:

{-|+}allow_postdated
-allow_postdated prohibits principals from obtaining postdated tickets. (Sets the KRB5_KDB_DISALLOW_POSTDATED flag.).+allow_postdated clears this flag.
{-|+}allow_forwardable
-allow_forwardable prohibits principals from obtaining forwardable tickets. (Sets the KRB5_KDB_DISALLOW_FORWARDABLE flag.) +allow_forwardable clears this flag.
{-|+}allow_renewable
-allow_renewable prohibits principals from obtaining renewable tickets. (Sets the KRB5_KDB_DISALLOW_RENEWABLE flag.) +allow_renewable clears this flag.
{-|+}allow_proxiable
-allow_proxiable prohibits principals from obtaining proxiable tickets. (Sets the KRB5_KDB_DISALLOW_PROXABLE flag.) +allow_proxiable clears this flag.
{-|+}allow_dup_skey
-allow_dup_skey Disables user-to-user authentication for principals by prohibiting principals from obtaining a sessions key for another user. (Sets the KRB5_KDB_DISALLOW_DUP_SKEY flag.). +allow_dup_skey clears This flag.
{-|+}requires_preauth
+requires_preauth requires principals to preauthenticate before being allowed to kinit. (Sets the KRB5_KDB_REQURES_PRE_AUTH flag.) -requires_preauth clears this flag.
{-|+}requires_hwauth
+requires_hwauth requires principals to preauthenticate using a hardware device before being allowed to kinit. (Sets the KRB5_KDB_REQURES_HW_AUTH flag.) -requires_hwauth clears this flag.
{-|+}allow_svr
-allow_svr prohibits the issuance of service tickets for principals. (Sets the KRB5_KDB_DISALLOW_SVR flag.) +allow_svr clears This flag.
{-|+}allow_tgs_req
-allow_tgs_req specifies that a Ticket-Granting Service (TGS) request for a service ticket for principals is not permitted. This option is useless for most things.+allow_tgs_req clears this flag. The default is +allow_tgs_req. In effect, -allow_tgs_req sets the KRB5_KDB_DISALLOW_TGT_BASED flag on principals in the database.
{-|+}allow_tix
-allow_tix forbids the issuance of any tickets for principals. +allow_tix clears this flag. The default is +allow_tix. In effect, -allow_tix sets the KRB5_KDB_DISALLOW_ALL_TIX flag on principals in the database.
{-|+}needchange
+needchange sets a flag in attributes field to force a password change; -needchange clears it. The default is -needchange. In effect, +needchange sets the KRB5_KDB_REQURES_PWCHANGE flag on principals in the database.
{-|+}password_changing_service
+password_changing_service sets a flag in the attributes field marking principal as a password change service principal (useless for most things). -password_changing_service clears the flag. This flag intentionally has a long name. The default is -password_changing_service. In effect, +password_changing_service sets the KRB5_KDB_PWCHANGE_SERVICE flag on principals in the database.
policy_name
Specifies the name of the ticket policy.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu create_policy
     -r ATHENA.MIT.EDU -maxtktlife "1 day" -maxrenewlife "1 week" -allow_forwardable usertktpolicy
     Password for "cn=admin,o=org":
     shell%


Next: , Previous: Creating and Modifying a Ticket Policy, Up: Global Operations on the Kerberos LDAP Database

5.6.8 Retrieving Information About a Ticket Policy

view_policy [-r realm] policy_name
view_policy
This option displays the attributes of a ticket policy. Option is as follows:
-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm(3) is used.
policy_name
Specifies the name of the ticket policy.

For example:

     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu view_policy
     -r ATHENA.MIT.EDU usertktpolicy
     Password for "cn=admin,o=org":
     Ticket policy: usertktpolicy
     Maxmum ticket life: 0 days 01:00:00
     Maxmum renewable life: 0 days 10:00:00
     Ticket flags: DISALLOW_FORWARDABLE REQUIRES_PWCHANGE
     shell%


Next: , Previous: Retrieving Information About a Ticket Policy, Up: Global Operations on the Kerberos LDAP Database

5.6.9 Destroying a Ticket Policy

destroy_policy [-force] [-r realm] policy_name
Destroys an existing ticket policy. Options are as follows:
-force
Forces the deletion of the policy object. If not specified, will be prompted for confirmation while deleting the policy. Enter yes to confirm the deletion.
-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm(3) is used.
policy_name
Specifies the name of the ticket policy.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
     destroy_policy -r ATHENA.MIT.EDU usertktpolicy
     Password for "cn=admin,o=org":
     This will delete the policy object 'usertktpolicy', are you sure?
     (type 'yes' to confirm)? Yes
     ** policy object 'usertktpolicy' deleted.
     shell%


Next: , Previous: Destroying a Ticket Policy, Up: Global Operations on the Kerberos LDAP Database

5.6.10 Listing available Ticket Policies

list_policy [-r realm]
Lists the name of ticket policies in a realm.

Option are as follows:

-r realm
Specifies the Kerberos realm of the database; by default the realm returned by krb5_default_local_realm(3) is used.

For example:

     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu list_policy -r ATHENA.MIT.EDU
     Password for "cn=admin,o=org":
     usertktpolicy
     tempusertktpolicy
     krbtktpolicy
     shell%


Next: , Previous: Listing available Ticket Policies, Up: Global Operations on the Kerberos LDAP Database

5.6.11 Creating a Service Object (eDirectory)

     create_service -kdc|-admin|-pwd [-servicehost service_host_list] [-realm realm_list] [-randpw|
     -fileonly] [-filename] service_dn

Creates a service object in directory and assigns appropriate rights on the container holding kerberos data.

Options are as follows:

-kdc
Specifies the KDC service
-admin
Specifies the Administration service
-pwd
Specifies the Password service
-servicehost service_host_list
Specifies the list of entries separated by a colon (:). Each entry consists of the hostname or IP address of the server hosting the service, transport protocol and the port number of the service separated by a pound sign (#). For example,
          server1#tcp#88:server2#udp#89.
     
-realm realm_list
Specifies the list of realms that are to be associated with this service. The list contains the name of the realms separated by a colon (:).
-randpw
Generates and sets a random password. This option is used to set the random password for the service object in directory and also to store it in the file. -fileonly option cannot be used with -randpw option.
-fileonly
Stores the password only in a file and not in directory. The -randpw option can not be used when -fileonly option is specified.
-f filename
Specifies the complete path of the file where the service object password is stashed. If this option is not specified, the default file will be /usr/local/var/service_passwd
service_dn
Specifies the Distinguished Name (DN) of the Kerberos service to be created.

For example:

          shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
          create_service -kdc -randpw -f /home/andrew/service_passwd cn=service-kdc,o=org
          Password for "cn=admin,o=org":
          File does not exist. Creating the file /home/andrew/service_passwd...
          shell%
     


Next: , Previous: Creating a Service Object (eDirectory), Up: Global Operations on the Kerberos LDAP Database

5.6.12 Modifying a Service Object (eDirectory)

     modify_service [-servicehost service_host_list |[-clearservicehost service_host_list] [-addservicehost service_host_list]] [-realm realm_list | [-clearrealm realm_list] [-addrealm realm_list]] service_dn

Modifies the attributes of a service and assigns appropriate rights, if realm associations are changed.

Options are as follows:

-servicehost service_host_list
List of entries separated by a colon (:) where each entry consists of host name or IP address of the server hosting the service, transport protocol, and port number of the service separated by a pound sign (#). This list replaces the existing list. For example,
          server1#tcp#88:server2#udp#89
     
-clearservicehost service_host_list
Specifies the list of servicehost entries to be removed from the existing list. This is a colon separated list.
-addservicehost service_host_list
Specifies the list of servicehost entries to be added to the existing list. This is a colon separated list.
-realm realm_list
Specifies the list of realms that are to be associated with this service. The list contains the name of the realms separated by a colon (:). This list replaces the existing list.
-clearrealm realm_list
Specifies the list of realms to be removed from the existing list. The list contains the name of the realms separated by a colon (:).
-addrealm realm_list
Specifies the list of realms to be added to the existing list. The list contains the name of the realms separated by a colon (:).
service_dn
Specifies the Distinguished Name (DN) of the Kerberos service to be modified.

For example:

     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
     modify_service -realm ATHENA.MIT.EDU cn=service-kdc,o=org
     Password for "cn=admin,o=org":
     Changing rights for the service object. Please wait ... done
     shell%


Next: , Previous: Modifying a Service Object (eDirectory), Up: Global Operations on the Kerberos LDAP Database

5.6.13 Retrieving Service Object Information (eDirectory)

view_service service_dn
Displays the attributes of a service. Options are as follows:
service_dn
Specifies the Distinguished name (DN) of the Kerberos service to be viewed.

For example:

     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
     view_service cn=service-kdc,o=org
     Password for "cn=admin,o=org":
     Service dn: cn=service-kdc,o=org
     Service type: kdc
     Service host list:
     Realm DN list: cn=ATHENA.MIT.EDU,cn=Kerberos,o=org
     shell%


Next: , Previous: Retrieving Service Object Information (eDirectory), Up: Global Operations on the Kerberos LDAP Database

5.6.14 Destroying a Service Object (eDirectory)

     destroy_service [-force] [-f stashfilename] service_dn

Destroys an existing service. Options are as follows :

-force
If specified, will not prompt for user's confirmation, instead will force destruction of service.
-f stashfilename
Complete path of the service password file from where the entry corresponding to the service_dn needs to be removed.
service_dn
Distinguished Name (DN) of the Kerberos service to be destroyed.
For example:
     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
     destroy_service cn=service-kdc,o=org
     Password for "cn=admin,o=org":
     This will delete the service object 'cn=service-kdc,o=org', are you sure?
     (type 'yes' to confirm)? Yes
     ** service object 'cn=service-kdc,o=org' deleted.
     shell%


Next: , Previous: Destroying a Service Object (eDirectory), Up: Global Operations on the Kerberos LDAP Database

5.6.15 Listing Available Service Objects (eDirectory)

list_service [-basedn base_dn]
Lists the name of services under a given base in directory. Options is as follows:
-basedn base_dn
Specifies the base DN for searching the policies, limiting the search to a particular subtree. If this option is not provided, LDAP Server specific search base will be used. For e.g., in the case of OpenLDAP, value of defaultsearchbase from slapd.conf file will be used, where as in the case of eDirectory, the default value for the base DN is Root.

For example:

     shell% kdb5_ldap_util -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu list_service
     Password for "cn=admin,o=org":
     cn=service-kdc,o=org
     cn=service-adm,o=org
     cn=service-pwd,o=org
     shell%


Previous: Listing Available Service Objects (eDirectory), Up: Global Operations on the Kerberos LDAP Database

5.6.16 Passwords for Service Objects (eDirectory)

setsrvpw [-randpw|-fileonly][-f filename] service_dn

Allows an administrator to set password for service objects such as KDC and Administration server in eDirectory and store them in a file. The -fileonly command stores the password in a file and not in the eDirectory object. Options are as follows:

-randpw
Generates and sets a random password on the directory object and stores it in the file. The -fileonly option can not be used if -randpw option is already specified.
-fileonly
Stores the password only in a file and not in eDirectory. The -randpw option can not be used when -fileonly option is specified.
-f filename
Specifies the complete path of the file where the service object password is stashed. If this option is not specified, the default file will be /usr/local/var/service_passwd.
service_dn
Specifies the Distinguished Name (DN) of the service object whose password is to be set.

For example:

     shell% kdb5_ldap_util setsrvpw -D cn=admin,o=org -H ldaps://ldap-server1.mit.edu
     setsrvpw -f /home/andrew/conf_keyfile cn=service-kdc,o=org
     Password for "cn=admin,o=org":
     Password for "cn=service-kdc,o=org":
     Re-enter password for "cn=service-kdc,o=org":
     shell%


Next: , Previous: Global Operations on the Kerberos LDAP Database, Up: Administrating the Kerberos Database

5.7 Cross-realm Authentication

In order for a KDC in one realm to authenticate Kerberos users in a different realm, it must share a key with the KDC in the other realm. In both databases, there must be krbtgt service principals for realms. These principals should all have the same passwords, key version numbers, and encryption types. For example, if the administrators of ATHENA.MIT.EDU and EXAMPLE.COM wanted to authenticate across the realms, they would run the following commands on the KDCs in both realms:

     shell%: kadmin.local -e "des3-hmac-sha1:normal des-cbc-crc:v4"
     kadmin: add_princ -requires_preauth krbtgt/ATHENA.MIT.EDU@EXAMPLE.COM
     Enter password for principal krbtgt/ATHENA.MIT.EDU@EXAMPLE.COM:
     Re-enter password for principal krbtgt/ATHENA.MIT.EDU@EXAMPLE.COM:
     kadmin: add_princ -requires_preauth krbtgt/EXAMPLE.COM@ATHENA.MIT.EDU
     Enter password for principal krbtgt/EXAMPLE.COM@ATHENA.MIT.EDU:
     Enter password for principal krbtgt/EXAMPLE.COM@ATHENA.MIT.EDU:
     kadmin:

Even if most principals in a realm are generally created with the requires_preauth flag enabled, this flag is not desirable on cross-realm authentication keys because doing so makes it impossible to disable preauthentication on a service-by-service basis. Disabling it as in the example above is recommended.

It is also very important that these principals have good passwords. MIT recommends that TGT principal passwords be at least 26 characters of random ASCII text.


Previous: Cross-realm Authentication, Up: Administrating the Kerberos Database

5.8 Changing the krbtgt Key

A Kerberos Ticket Granting Ticket (TGT) is a service ticket for the principal krbtgt/REALM. The key for this principal is created when the Kerberos database is initialized and need not be changed. However, it will only have the encryption types supported by the KDC at the time of the initial database creation. To allow use of newer encryption types for the TGT, this key has to be changed.

Changing this key using the normal kadmin change_password command would invalidate any previously issued TGTs. Therefore, when changing this key, normally one should use the -keepold flag to change_password to retain the previous key in the database as well as the new key. For example:

     kadmin: change_password -randkey -keepold krbtgt/ATHENA.MIT.EDU@ATHENA.MIT.EDU

There is currently no way to remove the old key without running change_password without the -keepold flag (and thereby invalidating all existing TGTs). After issuing this command, the old key is still valid and is still vulnerable to (for instance) brute force attacks. To completely retire an old key or encryption type, it's therefore currently necessary to declare a flag day, run change_password without the -keepold flag, and force all users to acquire new tickets.


Next: , Previous: Administrating the Kerberos Database, Up: Top

6 Configuring Kerberos with OpenLDAP back-end

  1. Set up SSL on the OpenLDAP server and client to ensure secure communication when the KDC service and LDAP server are on different machines. ldapi:// can be used if the LDAP server and KDC service are running on the same machine.
    1. Setting up SSL on the OpenLDAP server:
      1. Get a CA certificate using OpenSSL tools
      2. Configure OpenLDAP server for using SSL/TLS

        For the latter, you need to specify the location of CA certificate location in slapd.conf file.

        Refer to the following link for more information:

        http://www.openldap.org/doc/admin23/tls.html

    2. Setting up SSL on OpenLDAP Client:
      1. For the KDC and Admin Server, you need to do the client-side configuration in ldap.conf.

        For example,

                            TLS_CACERT /etc/openldap/certs/cacert.pem
                       
  2. Include the Kerberos schema file (kerberos.schema) in the configuration file (slapd.conf) on the LDAP Server, by providing the location where it is stored.
              include /etc/openldap/schema/kerberos.schema
         
  3. Configure the LDAP server ACLs to enable the KDC and Admin server to read and write the Kerberos data.

    Sample access control information

              access to dn.base=""
                      by * read
              
              access to dn.base="cn=Subschema"
                      by * read
              
              access to attrs=userPassword,userPKCS12
                      by self write
                      by * auth
              
              access to attrs=shadowLastChange
                      by self write
                      by * read
              
              # Providing access to realm subtree
              access to dn.subtree= "o=mit"
                      by dn.exact="cn=kdc-service,o=mit" read
                      by dn.exact="cn=adm-service,o=mit" write
                      by * none
              
              # Providing access to realm container
              access to dn.subtree= "cn=MIT.EDU,cn=Kerberos,o=mit"
                      by dn.exact="cn=kdc-service,o=mit" read
                      by dn.exact="cn=adm-service,o=mit" write
                      by * none
              
              access to *
                      by * read
         

    The above list provides the access control information for the KDC and Admin service object for the realm container and the realm subtree. Thus if the realm subtree or the service objects for a realm are changed then this information should be updated.

  4. Start the LDAP server as follows:
              slapd -h "ldapi:/// ldaps:///"
         
  5. Modify the krb5.conf file to include LDAP specific items listed below:
              realms
              database_module
              dbmodules
              db_library
              db_module_dir
              ldap_kdc_dn
              ldap_kadmind_dn
              ldap_service_password_file
              ldap_servers
              ldap_conns_per_server
         

    For the sample krb5.conf file, refer to Sample krb5.conf File. For more details, refer to the section krb5.conf

  6. Create the realm using kdb5_ldap_util.
              kdb5_ldap_util -D  cn=admin,o=mit create -subtrees  o=mit -r MIT.EDU -s
         

    Before executing the command, make sure that the subtree mentioned above (o=mit) exists.

    For more information, refer to the section Global Operations on the Kerberos LDAP Database.

    The realm object is created under the ldap_kerberos_container_dn specified in the configuration file. This operation will also create the Kerberos container, if not present already. This will be used to store information related to all realms.

  7. Stash the password of the service object used by the KDC and Administration service to bind to the LDAP server using the stashsrvpw command of kdb5_ldap_util. The object DN should be the same as ldap_kdc_dn and ldap_kadmind_dn values specified in the krb5.conf file.
              kdb5_ldap_util -D  cn=admin,o=mit stashsrvpw -f /etc/kerberos/service.keyfile cn=krbadmin,o=mit
         
  8. Add krb5principalname to the indexes in slapd.conf to speed up the access.


Next: , Previous: Configuring Kerberos with OpenLDAP back-end, Up: Top

7 Application Servers

If you need to install the Kerberos V5 programs on an application server, please refer to the Kerberos V5 Installation Guide. Once you have installed the software, you need to add that host to the Kerberos database (see Adding or Modifying Principals), and generate a keytab for that host, that contains the host's key. You also need to make sure the host's clock is within your maximum clock skew of the KDCs.


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7.1 Keytabs

A keytab is a host's copy of its own keylist, which is analogous to a user's password. An application server that needs to authenticate itself to the KDC has to have a keytab that contains its own principal and key. Just as it is important for users to protect their passwords, it is equally important for hosts to protect their keytabs. You should always store keytab files on local disk, and make them readable only by root, and you should never send a keytab file over a network in the clear. Ideally, you should run the kadmin command to extract a keytab on the host on which the keytab is to reside.


Next: , Previous: Keytabs, Up: Keytabs

7.1.1 Adding Principals to Keytabs

To generate a keytab, or to add a principal to an existing keytab, use the ktadd command from kadmin, which requires the “inquire” administrative privilege. (If you use the -glob princ_exp option, it also requires the “list” administrative privilege.) The syntax is:

     ktadd [-k[eytab] keytab] [-q] [-e
     key:salt_list] [principal | -glob princ_exp]
     [...]

The ktadd command takes the following switches:

-k[eytab] keytab
use keytab as the keytab file. Otherwise, ktadd will use the default keytab file (/etc/krb5.keytab).
-e "enc:salt..."
Uses the specified list of enctype-salttype pairs for setting the key of the principal. The quotes are necessary if there are multiple enctype-salttype pairs. This will not function against kadmin daemons earlier than krb5-1.2. See Supported Encryption Types and Salts for all possible values.
-q
run in quiet mode. This causes ktadd to display less verbose information.
principal | -glob principal expression
add principal, or all principals matching principal expression to the keytab. The rules for principal expression are the same as for the kadmin list_principals (see Retrieving a List of Principals) command.

Here is a sample session, using configuration files that enable only des-cbc-crc encryption. (The line beginning with => is a continuation of the previous line.)

     kadmin: ktadd host/daffodil.mit.edu@ATHENA.MIT.EDU
     kadmin: Entry for principal host/daffodil.mit.edu@ATHENA.MIT.EDU with
          kvno 2, encryption type DES-CBC-CRC added to keytab
          WRFILE:/etc/krb5.keytab.
     kadmin:
     kadmin: ktadd -k /usr/local/var/krb5kdc/kadmind.keytab
     => kadmin/admin kadmin/changepw
     kadmin: Entry for principal kadmin/admin@ATHENA.MIT.EDU with
          kvno 3, encryption type DES-CBC-CRC added to keytab
          WRFILE:/usr/local/var/krb5kdc/kadmind.keytab.
     kadmin:


Previous: Adding Principals to Keytabs, Up: Keytabs

7.1.2 Removing Principals from Keytabs

To remove a principal from an existing keytab, use the kadmin ktremove command. The syntax is:

     ktremove [-k[eytab] keytab] [-q] principal [kvno | all | old]

The ktremove command takes the following switches:

-k[eytab] keytab
use keytab as the keytab file. Otherwise, ktremove will use the default keytab file (/etc/krb5.keytab).
-q
run in quiet mode. This causes ktremove to display less verbose information.
principal
the principal to remove from the keytab. (Required.)
kvno
remove all entries for the specified principal whose Key Version Numbers match kvno.
all
remove all entries for the specified principal
old
remove all entries for the specified principal except those with the highest kvno.

For example:

     kadmin: ktremove -k /usr/local/var/krb5kdc/kadmind.keytab kadmin/admin
     kadmin: Entry for principal kadmin/admin with kvno 3 removed
          from keytab WRFILE:/usr/local/var/krb5kdc/kadmind.keytab.
     kadmin:


Next: , Previous: Keytabs, Up: Application Servers

7.2 Clock Skew

In order to prevent intruders from resetting their system clocks in order to continue to use expired tickets, Kerberos V5 is set up to reject ticket requests from any host whose clock is not within the specified maximum clock skew of the KDC (as specified in the kdc.conf file). Similarly, hosts are configured to reject responses from any KDC whose clock is not within the specified maximum clock skew of the host (as specified in the krb5.conf file). The default value for maximum clock skew is 300 seconds, or five minutes.

MIT suggests that you add a line to client machines' /etc/rc files to synchronize the machine's clock to your KDC at boot time. On UNIX hosts, assuming you had a kdc called kerberos in your realm, this would be:

     gettime -s kerberos

If the host is not likely to be rebooted frequently, you may also want to set up a cron job that adjusts the time on a regular basis.


Next: , Previous: Clock Skew, Up: Application Servers

7.3 Getting DNS Information Correct

Several aspects of Kerberos rely on name service. In order for Kerberos to provide its high level of security, it is less forgiving of name service problems than some other parts of your network. It is important that your Domain Name System (DNS) entries and your hosts have the correct information.

Each host's canonical name must be the fully-qualified host name (including the domain), and each host's IP address must reverse-resolve to the canonical name.

Other than the localhost entry, make all entries in each machine's /etc/hosts file in the following form:

     IP address      fully-qualified hostname        aliases

Here is a sample /etc/hosts file:

     # this is a comment
     127.0.0.1       localhost localhost@mit.edu
     10.0.0.6       daffodil.mit.edu trillium wake-robin

Additionally, on Solaris machines, you need to be sure the “hosts” entry in the file
/etc/nsswitch.conf includes the source “dns” as well as “file”.

Finally, each host's keytab file must include a host/key pair for the host's canonical name. You can list the keys in a keytab file by issuing the command klist -k. For example:

     viola# klist -k
     Keytab name: /etc/krb5.keytab
     KVNO Principal
     ---- ------------------------------------------------------------
        1 host/daffodil.mit.edu@ATHENA.MIT.EDU

If you telnet to the host with a fresh credentials cache (ticket file), and then klist, the host's service principal should be host/fully-qualified-hostname@REALM_NAME.


Previous: Getting DNS Information Correct, Up: Application Servers

7.4 Configuring Your Firewall to Work With Kerberos V5

If you need off-site users to be able to get Kerberos tickets in your realm, they must be able to get to your KDC. This requires either that you have a slave KDC outside your firewall, or you configure your firewall to allow UDP requests into at least one of your KDCs, on whichever port the KDC is running. (The default is port 88; other ports may be specified in the KDC's kdc.conf file.) Similarly, if you need off-site users to be able to change their passwords in your realm, they must be able to get to your Kerberos admin server. The default port for the admin server is 749.

If your on-site users inside your firewall will need to get to KDCs in other realms, you will also need to configure your firewall to allow outgoing TCP and UDP requests to port 88. Additionally, if they will need to get to any Kerberos V4 KDCs, you may also need to allow TCP and UDP requests to port 750. If your on-site users inside your firewall will need to get to Kerberos admin servers in other realms, you will also need to allow outgoing TCP and UDP requests to port 749.

If any of your KDCs are outside your firewall, you will need to allow kprop requests to get through to the remote KDC. Kprop uses the krb5_prop service on port 754 (tcp).

If you need your off-site users to have access to machines inside your firewall, you need to allow TCP connections from their off-site hosts on the appropriate ports for the programs they will be using. The following lines from /etc/services show the default port numbers for the Kerberos V5 programs:

     ftp           21/tcp           # Kerberos ftp and telnet use the
     telnet        23/tcp           # default ports
     kerberos      88/udp    kdc    # Kerberos V5 KDC
     kerberos      88/tcp    kdc    # Kerberos V5 KDC
     klogin        543/tcp          # Kerberos authenticated rlogin
     kshell        544/tcp   cmd    # and remote shell
     kerberos-adm  749/tcp          # Kerberos 5 admin/changepw
     kerberos-adm  749/udp          # Kerberos 5 admin/changepw
     krb5_prop     754/tcp          # Kerberos slave propagation
     
     eklogin       2105/tcp         # Kerberos auth. & encrypted rlogin
     krb524        4444/tcp         # Kerberos 5 to 4 ticket translator

By default, Kerberos V5 telnet and ftp use the same ports as the standard telnet and ftp programs, so if you already allow telnet and ftp connections through your firewall, the Kerberos V5 versions will get through as well. If you do not already allow telnet and ftp connections through your firewall, but need your users to be able to use Kerberos V5 telnet and ftp, you can either allow ftp and telnet connections on the standard ports, or switch these programs to non-default port numbers and allow ftp and telnet connections on those ports to get through.

Kerberos V5 rlogin uses the klogin service, which by default uses port 543. Encrypted Kerberos V5 rlogin uses the eklogin service, which by default uses port 2105.

Kerberos V5 rsh uses the kshell service, which by default uses port 544. However, the server must be able to make a TCP connection from the kshell port to an arbitrary port on the client, so if your users are to be able to use rsh from outside your firewall, the server they connect to must be able to send outgoing packets to arbitrary port numbers. Similarly, if your users need to run rsh from inside your firewall to hosts outside your firewall, the outside server needs to be able to connect to an arbitrary port on the machine inside your firewall. Because Kerberos V5 rcp uses rsh, the same issues apply. If you need to use rsh (or rcp) through your firewall and are concerned with the security implications of allowing connections to arbitrary ports, MIT suggests that you have rules that specifically name these applications and, if possible, list the allowed hosts.

The book UNIX System Security, by David Curry, is a good starting point for learning to configure firewalls.


Next: , Previous: Application Servers, Up: Top

8 Backups of Secure Hosts

When you back up a secure host, you should exclude the host's keytab file from the backup. If someone obtained a copy of the keytab from a backup, that person could make any host masquerade as the host whose keytab was compromised. This could be particularly dangerous if the compromised keytab was from one of your KDCs. If the machine has a disk crash and the keytab file is lost, it is easy to generate another keytab file. (See Adding Principals to Keytabs.) If you are unable to exclude particular files from backups, you should ensure that the backups are kept as secure as the host's root password.


Previous: Backups of Secure Hosts, Up: Backups of Secure Hosts

8.1 Backing Up the Kerberos Database

As with any file, it is possible that your Kerberos database could become corrupted. If this happens on one of the slave KDCs, you might never notice, since the next automatic propagation of the database would install a fresh copy. However, if it happens to the master KDC, the corrupted database would be propagated to all of the slaves during the next propagation. For this reason, MIT recommends that you back up your Kerberos database regularly. Because the master KDC is continuously dumping the database to a file in order to propagate it to the slave KDCs, it is a simple matter to have a cron job periodically copy the dump file to a secure machine elsewhere on your network. (Of course, it is important to make the host where these backups are stored as secure as your KDCs, and to encrypt its transmission across your network.) Then if your database becomes corrupted, you can load the most recent dump onto the master KDC. (See Restoring a Kerberos Database from a Dump File.)


Next: , Previous: Backups of Secure Hosts, Up: Top

9 Bug Reporting

In any complex software, there will be bugs. If you have successfully built and installed Kerberos V5, please use the krb5-send-pr program to fill out a Problem Report should you encounter any errors in our software.

Bug reports that include proposed fixes are especially welcome. If you do include fixes, please send them using either context diffs or unified diffs (using diff -c or diff -u, respectively). Please be careful when using “cut and paste” or other such means to copy a patch into a bug report; depending on the system being used, that can result in converting TAB characters into spaces, which makes applying the patches more difficult.

The krb5-send-pr program is installed in the directory /usr/local/sbin.

The krb5-send-pr program enters the problem report into our Problem Report Management System (PRMS), which automatically assigns it to the engineer best able to help you with problems in the assigned category.

The krb5-send-pr program will try to intelligently fill in as many fields as it can. You need to choose the category, class, severity, and priority of the problem, as well as giving us as much information as you can about its exact nature.

The PR category will be one of:

     krb5-admin   krb5-appl    krb5-build   krb5-clients
     krb5-doc     krb5-kdc     krb5-libs    krb5-misc
     pty          telnet       test

Choose the category that best describes the area under which your problem falls.

The class can be sw-bug, doc-bug, change-request, or support. The first two are exactly as their names imply. Use change-request when the software is behaving according to specifications, but you want to request changes in some feature or behavior. The support class is intended for more general questions about building or using Kerberos V5.

The severity of the problem indicates the problem's impact on the usability of Kerberos V5. If a problem is critical, that means the product, component or concept is completely non-operational, or some essential functionality is missing, and no workaround is known. A serious problem is one in which the product, component or concept is not working properly or significant functionality is missing. Problems that would otherwise be considered critical are rated serious when a workaround is known. A non-critical problem is one that is indeed a problem, but one that is having a minimal effect on your ability to use Kerberos V5. E.g., The product, component or concept is working in general, but lacks features, has irritating behavior, does something wrong, or doesn't match its documentation. The default severity is serious.

The priority indicates how urgent this particular problem is in relation to your work. Note that low priority does not imply low importance. A priority of high means a solution is needed as soon as possible. A priority of medium means the problem should be solved no later than the next release. A priority of low means the problem should be solved in a future release, but it is not important to your work how soon this happens. The default priority is medium.

Note that a given severity does not necessarily imply a given priority. For example, a non-critical problem might still have a high priority if you are faced with a hard deadline. Conversely, a serious problem might have a low priority if the feature it is disabling is one that you do not need.

It is important that you fill in the release field and tell us what changes you have made, if any.

A sample filled-out form from a company named “Toasters, Inc.” might look like this:

     To: krb5-bugs@mit.edu
     Subject: misspelled "Kerberos" in title of installation guide
     From: jcb
     Reply-To: jcb
     Cc:
     X-send-pr-version: 3.99
     
     
     >Submitter-Id:	mit
     >Originator:	Jeffrey C. Gilman Bigler
     >Organization:
     mit
     >Confidential:	no
     >Synopsis:	Misspelled "Kerberos" in title of installation guide
     >Severity:	non-critical
     >Priority:	low
     >Category:	krb5-doc
     >Class:		doc-bug
     >Release:	1.0-development
     >Environment:
     	<machine, os, target, libraries (multiple lines)>
     System: ULTRIX imbrium 4.2 0 RISC
     Machine: mips
     >Description:
             Misspelled "Kerberos" in title of "Kerboros V5 Installation Guide"
     >How-To-Repeat:
             N/A
     >Fix:
             Correct the spelling.

If the krb5-send-pr program does not work for you, or if you did not get far enough in the process to have an installed and working krb5-send-pr, you can generate your own form, using the above as an example.


Previous: Bug Reporting, Up: Top

Appendix A Appendix


Next: , Previous: Appendix, Up: Appendix

A.1 Kerberos Error Messages


Next: , Previous: Errors, Up: Errors

A.1.1 Kerberos V5 Library Error Codes

This is the Kerberos v5 library error code table. Protocol error codes are
ERROR_TABLE_BASE_krb5 + the protocol error code number; other error codes start at ERROR_TABLE_BASE_krb5 + 128.

  1. KRB5KDC_ERR_NONE: No error
  2. KRB5KDC_ERR_NAME_EXP: Client's entry in database has expired
  3. KRB5KDC_ERR_SERVICE_EXP: Server's entry in database has expired
  4. KRB5KDC_ERR_BAD_PVNO: Requested protocol version not supported
  5. KRB5KDC_ERR_C_OLD_MAST_KVNO: Client's key is encrypted in an old master key
  6. KRB5KDC_ERR_S_OLD_MAST_KVNO: Server's key is encrypted in an old master key
  7. KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN: Client not found in Kerberos database
  8. KRB5KDC_ERR_S_PRINCIPAL_UNKNOWN: Server not found in Kerberos database
  9. KRB5KDC_ERR_PRINCIPAL_NOT_UNIQUE: Principal has multiple entries in Kerberos database
  10. KRB5KDC_ERR_NULL_KEY: Client or server has a null key
  11. KRB5KDC_ERR_CANNOT_POSTDATE: Ticket is ineligible for postdating
  12. KRB5KDC_ERR_NEVER_VALID: Requested effective lifetime is negative or too short
  13. KRB5KDC_ERR_POLICY: KDC policy rejects request
  14. KRB5KDC_ERR_BADOPTION: KDC can't fulfill requested option
  15. KRB5KDC_ERR_ETYPE_NOSUPP: KDC has no support for encryption type
  16. KRB5KDC_ERR_SUMTYPE_NOSUPP: KDC has no support for checksum type
  17. KRB5KDC_ERR_PADATA_TYPE_NOSUPP: KDC has no support for padata type
  18. KRB5KDC_ERR_TRTYPE_NOSUPP: KDC has no support for transited type
  19. KRB5KDC_ERR_CLIENT_REVOKED: Clients credentials have been revoked
  20. KRB5KDC_ERR_SERVICE_REVOKED: Credentials for server have been revoked
  21. KRB5KDC_ERR_TGT_REVOKED: TGT has been revoked
  22. KRB5KDC_ERR_CLIENT_NOTYET: Client not yet valid - try again later
  23. KRB5KDC_ERR_SERVICE_NOTYET: Server not yet valid - try again later
  24. KRB5KDC_ERR_KEY_EXP: Password has expired
  25. KRB5KDC_ERR_PREAUTH_FAILED: Preauthentication failed
  26. KRB5KDC_ERR_PREAUTH_REQUIRED: Additional pre-authentication required
  27. KRB5KDC_ERR_SERVER_NOMATCH: Requested server and ticket don't match
  28. KRB5PLACEHOLD_27: KRB5 error code 27
  29. KRB5PLACEHOLD_28: KRB5 error code 28
  30. KRB5PLACEHOLD_29: KRB5 error code 29
  31. KRB5PLACEHOLD_30: KRB5 error code 30
  32. KRB5KRB_AP_ERR_BAD_INTEGRITY: Decrypt integrity check failed
  33. KRB5KRB_AP_ERR_TKT_EXPIRED: Ticket expired
  34. KRB5KRB_AP_ERR_TKT_NYV: Ticket not yet valid
  35. KRB5KRB_AP_ERR_REPEAT: Request is a replay
  36. KRB5KRB_AP_ERR_NOT_US: The ticket isn't for us
  37. KRB5KRB_AP_ERR_BADMATCH: Ticket/authenticator don't match
  38. KRB5KRB_AP_ERR_SKEW: Clock skew too great
  39. KRB5KRB_AP_ERR_BADADDR: Incorrect net address
  40. KRB5KRB_AP_ERR_BADVERSION: Protocol version mismatch
  41. KRB5KRB_AP_ERR_MSG_TYPE: Invalid message type
  42. KRB5KRB_AP_ERR_MODIFIED: Message stream modified
  43. KRB5KRB_AP_ERR_BADORDER: Message out of order
  44. KRB5KRB_AP_ERR_ILL_CR_TKT: Illegal cross-realm ticket
  45. KRB5KRB_AP_ERR_BADKEYVER: Key version is not available
  46. KRB5KRB_AP_ERR_NOKEY: Service key not available
  47. KRB5KRB_AP_ERR_MUT_FAIL: Mutual authentication failed
  48. KRB5KRB_AP_ERR_BADDIRECTION: Incorrect message direction
  49. KRB5KRB_AP_ERR_METHOD: Alternative authentication method required
  50. KRB5KRB_AP_ERR_BADSEQ: Incorrect sequence number in message
  51. KRB5KRB_AP_ERR_INAPP_CKSUM: Inappropriate type of checksum in message
  52. KRB5KRB_AP_PATH_NOT_ACCEPTED: Policy rejects transited path
  53. KRB5KRB_ERR_RESPONSE_TOO_BIG: Response too big for UDP, retry with TCP
  54. KRB5PLACEHOLD_53: KRB5 error code 53
  55. KRB5PLACEHOLD_54: KRB5 error code 54
  56. KRB5PLACEHOLD_55: KRB5 error code 55
  57. KRB5PLACEHOLD_56: KRB5 error code 56
  58. KRB5PLACEHOLD_57: KRB5 error code 57
  59. KRB5PLACEHOLD_58: KRB5 error code 58
  60. KRB5PLACEHOLD_59: KRB5 error code 59
  61. KRB5KRB_ERR_GENERIC: Generic error (see e-text)
  62. KRB5KRB_ERR_FIELD_TOOLONG: Field is too long for this implementation
  63. KRB5PLACEHOLD_62: KRB5 error code 62
  64. KRB5PLACEHOLD_63: KRB5 error code 63
  65. KRB5PLACEHOLD_64: KRB5 error code 64
  66. KRB5PLACEHOLD_65: KRB5 error code 65
  67. KRB5PLACEHOLD_66: KRB5 error code 66
  68. KRB5PLACEHOLD_67: KRB5 error code 67
  69. KRB5PLACEHOLD_68: KRB5 error code 68
  70. KRB5PLACEHOLD_69: KRB5 error code 69
  71. KRB5PLACEHOLD_70: KRB5 error code 70
  72. KRB5PLACEHOLD_71: KRB5 error code 71
  73. KRB5PLACEHOLD_72: KRB5 error code 72
  74. KRB5PLACEHOLD_73: KRB5 error code 73
  75. KRB5PLACEHOLD_74: KRB5 error code 74
  76. KRB5PLACEHOLD_75: KRB5 error code 75
  77. KRB5PLACEHOLD_76: KRB5 error code 76
  78. KRB5PLACEHOLD_77: KRB5 error code 77
  79. KRB5PLACEHOLD_78: KRB5 error code 78
  80. KRB5PLACEHOLD_79: KRB5 error code 79
  81. KRB5PLACEHOLD_80: KRB5 error code 80
  82. KRB5PLACEHOLD_81: KRB5 error code 81
  83. KRB5PLACEHOLD_82: KRB5 error code 82
  84. KRB5PLACEHOLD_83: KRB5 error code 83
  85. KRB5PLACEHOLD_84: KRB5 error code 84
  86. KRB5PLACEHOLD_85: KRB5 error code 85
  87. KRB5PLACEHOLD_86: KRB5 error code 86
  88. KRB5PLACEHOLD_87: KRB5 error code 87
  89. KRB5PLACEHOLD_88: KRB5 error code 88
  90. KRB5PLACEHOLD_89: KRB5 error code 89
  91. KRB5PLACEHOLD_90: KRB5 error code 90
  92. KRB5PLACEHOLD_91: KRB5 error code 91
  93. KRB5PLACEHOLD_92: KRB5 error code 92
  94. KRB5PLACEHOLD_93: KRB5 error code 93
  95. KRB5PLACEHOLD_94: KRB5 error code 94
  96. KRB5PLACEHOLD_95: KRB5 error code 95
  97. KRB5PLACEHOLD_96: KRB5 error code 96
  98. KRB5PLACEHOLD_97: KRB5 error code 97
  99. KRB5PLACEHOLD_98: KRB5 error code 98
  100. KRB5PLACEHOLD_99: KRB5 error code 99
  101. KRB5PLACEHOLD_100: KRB5 error code 100
  102. KRB5PLACEHOLD_101: KRB5 error code 101
  103. KRB5PLACEHOLD_102: KRB5 error code 102
  104. KRB5PLACEHOLD_103: KRB5 error code 103
  105. KRB5PLACEHOLD_104: KRB5 error code 104
  106. KRB5PLACEHOLD_105: KRB5 error code 105
  107. KRB5PLACEHOLD_106: KRB5 error code 106
  108. KRB5PLACEHOLD_107: KRB5 error code 107
  109. KRB5PLACEHOLD_108: KRB5 error code 108
  110. KRB5PLACEHOLD_109: KRB5 error code 109
  111. KRB5PLACEHOLD_110: KRB5 error code 110
  112. KRB5PLACEHOLD_111: KRB5 error code 111
  113. KRB5PLACEHOLD_112: KRB5 error code 112
  114. KRB5PLACEHOLD_113: KRB5 error code 113
  115. KRB5PLACEHOLD_114: KRB5 error code 114
  116. KRB5PLACEHOLD_115: KRB5 error code 115
  117. KRB5PLACEHOLD_116: KRB5 error code 116
  118. KRB5PLACEHOLD_117: KRB5 error code 117
  119. KRB5PLACEHOLD_118: KRB5 error code 118
  120. KRB5PLACEHOLD_119: KRB5 error code 119
  121. KRB5PLACEHOLD_120: KRB5 error code 120
  122. KRB5PLACEHOLD_121: KRB5 error code 121
  123. KRB5PLACEHOLD_122: KRB5 error code 122
  124. KRB5PLACEHOLD_123: KRB5 error code 123
  125. KRB5PLACEHOLD_124: KRB5 error code 124
  126. KRB5PLACEHOLD_125: KRB5 error code 125
  127. KRB5PLACEHOLD_126: KRB5 error code 126
  128. KRB5PLACEHOLD_127: KRB5 error code 127
  129. KRB5_ERR_RCSID: (RCS Id string for the krb5 error table)
  130. KRB5_LIBOS_BADLOCKFLAG: Invalid flag for file lock mode
  131. KRB5_LIBOS_CANTREADPWD: Cannot read password
  132. KRB5_LIBOS_BADPWDMATCH: Password mismatch
  133. KRB5_LIBOS_PWDINTR: Password read interrupted
  134. KRB5_PARSE_ILLCHAR: Illegal character in component name
  135. KRB5_PARSE_MALFORMED: Malformed representation of principal
  136. KRB5_CONFIG_CANTOPEN: Can't open/find Kerberos configuration file
  137. KRB5_CONFIG_BADFORMAT: Improper format of Kerberos configuration file
  138. KRB5_CONFIG_NOTENUFSPACE: Insufficient space to return complete information
  139. KRB5_BADMSGTYPE: Invalid message type specified for encoding
  140. KRB5_CC_BADNAME: Credential cache name malformed
  141. KRB5_CC_UNKNOWN_TYPE: Unknown credential cache type
  142. KRB5_CC_NOTFOUND: Matching credential not found
  143. KRB5_CC_END: End of credential cache reached
  144. KRB5_NO_TKT_SUPPLIED: Request did not supply a ticket
  145. KRB5KRB_AP_WRONG_PRINC: Wrong principal in request
  146. KRB5KRB_AP_ERR_TKT_INVALID: Ticket has invalid flag set
  147. KRB5_PRINC_NOMATCH: Requested principal and ticket don't match
  148. KRB5_KDCREP_MODIFIED: KDC reply did not match expectations
  149. KRB5_KDCREP_SKEW: Clock skew too great in KDC reply
  150. KRB5_IN_TKT_REALM_MISMATCH: Client/server realm mismatch in initial ticket request
  151. KRB5_PROG_ETYPE_NOSUPP: Program lacks support for encryption type
  152. KRB5_PROG_KEYTYPE_NOSUPP: Program lacks support for key type
  153. KRB5_WRONG_ETYPE: Requested encryption type not used in message
  154. KRB5_PROG_SUMTYPE_NOSUPP: Program lacks support for checksum type
  155. KRB5_REALM_UNKNOWN: Cannot find KDC for requested realm
  156. KRB5_SERVICE_UNKNOWN: Kerberos service unknown
  157. KRB5_KDC_UNREACH: Cannot contact any KDC for requested realm
  158. KRB5_NO_LOCALNAME: No local name found for principal name
  159. KRB5_MUTUAL_FAILED: Mutual authentication failed
  160. KRB5_RC_TYPE_EXISTS: Replay cache type is already registered
  161. KRB5_RC_MALLOC: No more memory to allocate (in replay cache code)
  162. KRB5_RC_TYPE_NOTFOUND: Replay cache type is unknown
  163. KRB5_RC_UNKNOWN: Generic unknown RC error
  164. KRB5_RC_REPLAY: Message is a replay
  165. KRB5_RC_IO: Replay I/O operation failed XXX
  166. KRB5_RC_NOIO: Replay cache type does not support non-volatile storage
  167. KRB5_RC_PARSE: Replay cache name parse/format error
  168. KRB5_RC_IO_EOF: End-of-file on replay cache I/O
  169. KRB5_RC_IO_MALLOC: No more memory to allocate (in replay cache I/O code)
  170. KRB5_RC_IO_PERM: Permission denied in replay cache code
  171. KRB5_RC_IO_IO: I/O error in replay cache i/o code
  172. KRB5_RC_IO_UNKNOWN: Generic unknown RC/IO error
  173. KRB5_RC_IO_SPACE: Insufficient system space to store replay information
  174. KRB5_TRANS_CANTOPEN: Can't open/find realm translation file
  175. KRB5_TRANS_BADFORMAT: Improper format of realm translation file
  176. KRB5_LNAME_CANTOPEN: Can't open/find lname translation database
  177. KRB5_LNAME_NOTRANS: No translation available for requested principal
  178. KRB5_LNAME_BADFORMAT: Improper format of translation database entry
  179. KRB5_CRYPTO_INTERNAL: Cryptosystem internal error
  180. KRB5_KT_BADNAME: Key table name malformed
  181. KRB5_KT_UNKNOWN_TYPE: Unknown Key table type
  182. KRB5_KT_NOTFOUND: Key table entry not found
  183. KRB5_KT_END: End of key table reached
  184. KRB5_KT_NOWRITE: Cannot write to specified key table
  185. KRB5_KT_IOERR: Error writing to key table
  186. KRB5_NO_TKT_IN_RLM: Cannot find ticket for requested realm
  187. KRB5DES_BAD_KEYPAR: DES key has bad parity
  188. KRB5DES_WEAK_KEY: DES key is a weak key
  189. KRB5_BAD_ENCTYPE: Bad encryption type
  190. KRB5_BAD_KEYSIZE: Key size is incompatible with encryption type
  191. KRB5_BAD_MSIZE: Message size is incompatible with encryption type
  192. KRB5_CC_TYPE_EXISTS: Credentials cache type is already registered.
  193. KRB5_KT_TYPE_EXISTS: Key table type is already registered.
  194. KRB5_CC_IO: Credentials cache I/O operation failed XXX
  195. KRB5_FCC_PERM: Credentials cache file permissions incorrect
  196. KRB5_FCC_NOFILE: No credentials cache found
  197. KRB5_FCC_INTERNAL: Internal credentials cache error
  198. KRB5_CC_WRITE: Error writing to credentials cache
  199. KRB5_CC_NOMEM: No more memory to allocate (in credentials cache code)
  200. KRB5_CC_FORMAT: Bad format in credentials cache
  201. KRB5_INVALID_FLAGS: Invalid KDC option combination (library internal error) [for dual tgt library calls]
  202. KRB5_NO_2ND_TKT: Request missing second ticket [for dual tgt library calls]
  203. KRB5_NOCREDS_SUPPLIED: No credentials supplied to library routine
  204. KRB5_SENDAUTH_BADAUTHVERS: Bad sendauth version was sent
  205. KRB5_SENDAUTH_BADAPPLVERS: Bad application version was sent (via sendauth)
  206. KRB5_SENDAUTH_BADRESPONSE: Bad response (during sendauth exchange)
  207. KRB5_SENDAUTH_REJECTED: Server rejected authentication (during sendauth exchange)
  208. KRB5_PREAUTH_BAD_TYPE: Unsupported preauthentication type
  209. KRB5_PREAUTH_NO_KEY: Required preauthentication key not supplied
  210. KRB5_PREAUTH_FAILED: Generic preauthentication failure
  211. KRB5_RCACHE_BADVNO: Unsupported replay cache format version number
  212. KRB5_CCACHE_BADVNO: Unsupported credentials cache format version number
  213. KRB5_KEYTAB_BADVNO: Unsupported key table format version number
  214. KRB5_PROG_ATYPE_NOSUPP: Program lacks support for address type
  215. KRB5_RC_REQUIRED: Message replay detection requires rcache parameter
  216. KRB5_ERR_BAD_HOSTNAME: Hostname cannot be canonicalized
  217. KRB5_ERR_HOST_REALM_UNKNOWN: Cannot determine realm for host
  218. KRB5_SNAME_UNSUPP_NAMETYPE: Conversion to service principal undefined for name type
  219. KRB5KRB_AP_ERR_V4_REPLY: Initial Ticket response appears to be Version 4 error
  220. KRB5_REALM_CANT_RESOLVE: Cannot resolve KDC for requested realm
  221. KRB5_TKT_NOT_FORWARDABLE: Requesting ticket can't get forwardable tickets
  222. KRB5_FWD_BAD_PRINCIPAL: Bad principal name while trying to forward credentials
  223. KRB5_GET_IN_TKT_LOOP: Looping detected inside krb5_get_in_tkt
  224. KRB5_CONFIG_NODEFREALM: Configuration file does not specify default realm
  225. KRB5_SAM_UNSUPPORTED: Bad SAM flags in obtain_sam_padata
  226. KRB5_KT_NAME_TOOLONG: Keytab name too long
  227. KRB5_KT_KVNONOTFOUND: Key version number for principal in key table is incorrect
  228. KRB5_APPL_EXPIRED: This application has expired
  229. KRB5_LIB_EXPIRED: This Krb5 library has expired
  230. KRB5_CHPW_PWDNULL: New password cannot be zero length
  231. KRB5_CHPW_FAIL: Password change failed
  232. KRB5_KT_FORMAT: Bad format in keytab
  233. KRB5_NOPERM_ETYPE: Encryption type not permitted
  234. KRB5_CONFIG_ETYPE_NOSUPP: No supported encryption types (config file error?)
  235. KRB5_OBSOLETE_FN: Program called an obsolete, deleted function
  236. KRB5_EAI_FAIL: unknown getaddrinfo failure
  237. KRB5_EAI_NODATA: no data available for host/domain name
  238. KRB5_EAI_NONAME: host/domain name not found
  239. KRB5_EAI_SERVICE: service name unknown
  240. KRB5_ERR_NUMERIC_REALM: Cannot determine realm for numeric host address


Next: , Previous: Kerberos V5 Library Error Codes, Up: Errors

A.1.2 Kerberos V5 Database Library Error Codes

This is the Kerberos v5 database library error code table.

  1. KRB5_KDB_RCSID: (RCS Id string for the kdb error table)
  2. KRB5_KDB_INUSE: Entry already exists in database
  3. KRB5_KDB_UK_SERROR: Database store error
  4. KRB5_KDB_UK_RERROR: Database read error
  5. KRB5_KDB_UNAUTH: Insufficient access to perform requested operation
  6. KRB5_KDB_NOENTRY: No such entry in the database
  7. KRB5_KDB_ILL_WILDCARD: Illegal use of wildcard
  8. KRB5_KDB_DB_INUSE: Database is locked or in use–try again later
  9. KRB5_KDB_DB_CHANGED: Database was modified during read
  10. KRB5_KDB_TRUNCATED_RECORD: Database record is incomplete or corrupted
  11. KRB5_KDB_RECURSIVELOCK: Attempt to lock database twice
  12. KRB5_KDB_NOTLOCKED: Attempt to unlock database when not locked
  13. KRB5_KDB_BADLOCKMODE: Invalid kdb lock mode
  14. KRB5_KDB_DBNOTINITED: Database has not been initialized
  15. KRB5_KDB_DBINITED: Database has already been initialized
  16. KRB5_KDB_ILLDIRECTION: Bad direction for converting keys
  17. KRB5_KDB_NOMASTERKEY: Cannot find master key record in database
  18. KRB5_KDB_BADMASTERKEY: Master key does not match database
  19. KRB5_KDB_INVALIDKEYSIZE: Key size in database is invalid
  20. KRB5_KDB_CANTREAD_STORED: Cannot find/read stored master key
  21. KRB5_KDB_BADSTORED_MKEY: Stored master key is corrupted
  22. KRB5_KDB_CANTLOCK_DB: Insufficient access to lock database
  23. KRB5_KDB_DB_CORRUPT: Database format error
  24. KRB5_KDB_BAD_VERSION: Unsupported version in database entry
  25. KRB5_KDB_BAD_SALTTYPE: Unsupported salt type
  26. KRB5_KDB_BAD_ENCTYPE: Unsupported encryption type
  27. KRB5_KDB_BAD_CREATEFLAGS: Bad database creation flags
  28. KRB5_KDB_NO_PERMITTED_KEY: No matching key in entry having a permitted enc type
  29. KRB5_KDB_NO_MATCHING_KEY: No matching key in entry
  30. KRB5_KDB_SERVER_INTERNAL_ERR: Server error
  31. KRB5_KDB_ACCESS_ERROR: Unable to access Kerberos database
  32. KRB5_KDB_INTERNAL_ERROR:Kerberos database internal error
  33. KRB5_KDB_CONSTRAINT_VIOLATION:Kerberos database constraints violated


Next: , Previous: Kerberos V5 Database Library Error Codes, Up: Errors

A.1.3 Kerberos V5 Magic Numbers Error Codes

This is the Kerberos v5 magic numbers error code table.

  1. KV5M_NONE: Kerberos V5 magic number table
  2. KV5M_PRINCIPAL: Bad magic number for krb5_principal structure
  3. KV5M_DATA: Bad magic number for krb5_data structure
  4. KV5M_KEYBLOCK: Bad magic number for krb5_keyblock structure
  5. KV5M_CHECKSUM: Bad magic number for krb5_checksum structure
  6. KV5M_ENCRYPT_BLOCK: Bad magic number for krb5_encrypt_block structure
  7. KV5M_ENC_DATA: Bad magic number for krb5_enc_data structure
  8. KV5M_CRYPTOSYSTEM_ENTRY: Bad magic number for krb5_cryptosystem_entry structure
  9. KV5M_CS_TABLE_ENTRY: Bad magic number for krb5_cs_table_entry structure
  10. KV5M_CHECKSUM_ENTRY: Bad magic number for krb5_checksum_entry structure
  11. KV5M_AUTHDATA: Bad magic number for krb5_authdata structure
  12. KV5M_TRANSITED: Bad magic number for krb5_transited structure
  13. KV5M_ENC_TKT_PART: Bad magic number for krb5_enc_tkt_part structure
  14. KV5M_TICKET: Bad magic number for krb5_ticket structure
  15. KV5M_AUTHENTICATOR: Bad magic number for krb5_authenticator structure
  16. KV5M_TKT_AUTHENT: Bad magic number for krb5_tkt_authent structure
  17. KV5M_CREDS: Bad magic number for krb5_creds structure
  18. KV5M_LAST_REQ_ENTRY: Bad magic number for krb5_last_req_entry structure
  19. KV5M_PA_DATA: Bad magic number for krb5_pa_data structure
  20. KV5M_KDC_REQ: Bad magic number for krb5_kdc_req structure
  21. KV5M_ENC_KDC_REP_PART: Bad magic number for
    krb5_enc_kdc_rep_part structure
  22. KV5M_KDC_REP: Bad magic number for krb5_kdc_rep structure
  23. KV5M_ERROR: Bad magic number for krb5_error structure
  24. KV5M_AP_REQ: Bad magic number for krb5_ap_req structure
  25. KV5M_AP_REP: Bad magic number for krb5_ap_rep structure
  26. KV5M_AP_REP_ENC_PART: Bad magic number for
    krb5_ap_rep_enc_part structure
  27. KV5M_RESPONSE: Bad magic number for krb5_response structure
  28. KV5M_SAFE: Bad magic number for krb5_safe structure
  29. KV5M_PRIV: Bad magic number for krb5_priv structure
  30. KV5M_PRIV_ENC_PART: Bad magic number for krb5_priv_enc_part structure
  31. KV5M_CRED: Bad magic number for krb5_cred structure
  32. KV5M_CRED_INFO: Bad magic number for krb5_cred_info structure
  33. KV5M_CRED_ENC_PART: Bad magic number for krb5_cred_enc_part structure
  34. KV5M_PWD_DATA: Bad magic number for krb5_pwd_data structure
  35. KV5M_ADDRESS: Bad magic number for krb5_address structure
  36. KV5M_KEYTAB_ENTRY: Bad magic number for krb5_keytab_entry structure
  37. KV5M_CONTEXT: Bad magic number for krb5_context structure
  38. KV5M_OS_CONTEXT: Bad magic number for krb5_os_context structure
  39. KV5M_ALT_METHOD: Bad magic number for krb5_alt_method structure
  40. KV5M_ETYPE_INFO_ENTRY: Bad magic number for
    krb5_etype_info_entry structure
  41. KV5M_DB_CONTEXT: Bad magic number for krb5_db_context structure
  42. KV5M_AUTH_CONTEXT: Bad magic number for krb5_auth_context structure
  43. KV5M_KEYTAB: Bad magic number for krb5_keytab structure
  44. KV5M_RCACHE: Bad magic number for krb5_rcache structure
  45. KV5M_CCACHE: Bad magic number for krb5_ccache structure
  46. KV5M_PREAUTH_OPS: Bad magic number for krb5_preauth_ops
  47. KV5M_SAM_CHALLENGE: Bad magic number for krb5_sam_challenge
  48. KV5M_SAM_KEY: Bad magic number for krb5_sam_key
  49. KV5M_ENC_SAM_RESPONSE_ENC: Bad magic number for
    krb5_enc_sam_response_enc
  50. KV5M_SAM_RESPONSE: Bad magic number for krb5_sam_response
  51. KV5M_PREDICTED_SAM_RESPONSE: Bad magic number for krb5_predicted_sam_response
  52. KV5M_PASSWD_PHRASE_ELEMENT: Bad magic number for passwd_phrase_element
  53. KV5M_GSS_OID: Bad magic number for GSSAPI OID
  54. KV5M_GSS_QUEUE: Bad magic number for GSSAPI QUEUE


Next: , Previous: Kerberos V5 Magic Numbers Error Codes, Up: Errors

A.1.4 ASN.1 Error Codes

  1. ASN1_BAD_TIMEFORMAT: ASN.1 failed call to system time library
  2. ASN1_MISSING_FIELD: ASN.1 structure is missing a required field
  3. ASN1_MISPLACED_FIELD: ASN.1 unexpected field number
  4. ASN1_TYPE_MISMATCH: ASN.1 type numbers are inconsistent
  5. ASN1_OVERFLOW: ASN.1 value too large
  6. ASN1_OVERRUN: ASN.1 encoding ended unexpectedly
  7. ASN1_BAD_ID: ASN.1 identifier doesn't match expected value
  8. ASN1_BAD_LENGTH: ASN.1 length doesn't match expected value
  9. ASN1_BAD_FORMAT: ASN.1 badly-formatted encoding
  10. ASN1_PARSE_ERROR: ASN.1 parse error
  11. ASN1_BAD_GMTIME: ASN.1 bad return from gmtime
  12. ASN1_MISMATCH_INDEF: ASN.1 non-constructed indefinite encoding
  13. ASN1_MISSING_EOC: ASN.1 missing expected EOC


Previous: ASN.1 Error Codes, Up: Errors

A.1.5 GSSAPI Error Codes

Generic GSSAPI Errors:

  1. G_BAD_SERVICE_NAME: No in SERVICE-NAME name string
  2. G_BAD_STRING_UID: STRING-UID-NAME contains nondigits
  3. G_NOUSER: UID does not resolve to username
  4. G_VALIDATE_FAILED: Validation error
  5. G_BUFFER_ALLOC: Couldn't allocate gss_buffer_t data
  6. G_BAD_MSG_CTX: Message context invalid
  7. G_WRONG_SIZE: Buffer is the wrong size
  8. G_BAD_USAGE: Credential usage type is unknown
  9. G_UNKNOWN_QOP: Unknown quality of protection specified
  10. G_BAD_HOSTNAME: Hostname in SERVICE-NAME string could not be canonicalized
  11. G_WRONG_MECH: Mechanism is incorrect
  12. G_BAD_TOK_HEADER: Token header is malformed or corrupt
  13. G_BAD_DIRECTION: Packet was replayed in wrong direction
  14. G_TOK_TRUNC: Token is missing data
  15. G_REFLECT: Token was reflected
  16. G_WRONG_TOKID: Received token ID does not match expected token ID

Kerberos 5 GSSAPI Errors:

  1. KG_CCACHE_NOMATCH: Principal in credential cache does not match desired name
  2. KG_KEYTAB_NOMATCH: No principal in keytab matches desired name
  3. KG_TGT_MISSING: Credential cache has no TGT
  4. KG_NO_SUBKEY: Authenticator has no subkey
  5. KG_CONTEXT_ESTABLISHED: Context is already fully established
  6. KG_BAD_SIGN_TYPE: Unknown signature type in token
  7. KG_BAD_LENGTH: Invalid field length in token
  8. KG_CTX_INCOMPLETE: Attempt to use incomplete security context
  9. KG_CONTEXT: Bad magic number for krb5_gss_ctx_id_t
  10. KG_CRED: Bad magic number for krb5_gss_cred_id_t
  11. KG_ENC_DESC: Bad magic number for krb5_gss_enc_desc
  12. KG_BAD_SEQ: Sequence number in token is corrupt
  13. KG_EMPTY_CCACHE: Credential cache is empty
  14. KG_NO_CTYPES: Acceptor and Initiator share no checksum types


Previous: Errors, Up: Appendix

A.2 kadmin Time Zones

This is a complete listing of the time zones recognized by the kadmin command.

gmt
Greenwich Mean Time
ut, utc
Universal Time (Coordinated).
wet
Western European Time. (Same as GMT.)
bst
British Summer Time. (1 hour ahead of GMT.)
wat
West Africa Time. (1 hour behind GMT.)
at
Azores Time. (2 hours behind GMT.)
bst
Brazil Standard Time. (3 hours behind GMT.) Note that the abbreviation BST also stands for British Summer Time.
gst
Greenland Standard Time. (3 hours behind GMT.) Note that the abbreviation GST also stands for Guam Standard Time.
nft
Newfoundland Time. (3.5 hours behind GMT.)
nst
Newfoundland Standard Time. (3.5 hours behind GMT.)
ndt
Newfoundland Daylight Time. (2.5 hours behind GMT.)
ast
Atlantic Standard Time. (4 hours behind GMT.)
adt
Atlantic Daylight Time. (3 hours behind GMT.)
est
Eastern Standard Time. (5 hours behind GMT.)
edt
Eastern Daylight Time. (4 hours behind GMT.)
cst
Central Standard Time. (6 hours behind GMT.)
cdt
Central Daylight Time. (5 hours behind GMT.)
mst
Mountain Standard Time. (7 hours behind GMT.)
mdt
Mountain Daylight Time. (6 hours behind GMT.)
pst
Pacific Standard Time. (8 hours behind GMT.)
pdt
Pacific Daylight Time. (7 hours behind GMT.)
yst
Yukon Standard Time. (9 hours behind GMT.)
ydt
Yukon Daylight Time. (8 hours behind GMT.)
hst
Hawaii Standard Time. (10 hours behind GMT.)
hdt
Hawaii Daylight Time. (9 hours behind GMT.)
cat
Central Alaska Time. (10 hours behind GMT.)
ahst
Alaska-Hawaii Standard Time. (10 hours behind GMT.)
nt
Nome Time. (11 hours behind GMT.)
idlw
International Date Line West Time. (12 hours behind GMT.)
cet
Central European Time. (1 hour ahead of GMT.)
met
Middle European Time. (1 hour ahead of GMT.)
mewt
Middle European Winter Time. (1 hour ahead of GMT.)
mest
Middle European Summer Time. (2 hours ahead of GMT.)
swt
Swedish Winter Time. (1 hour ahead of GMT.)
sst
Swedish Summer Time. (1 hours ahead of GMT.)
fwt
French Winter Time. (1 hour ahead of GMT.)
fst
French Summer Time. (2 hours ahead of GMT.)
eet
Eastern Europe Time; Russia Zone 1. (2 hours ahead of GMT.)
bt
Baghdad Time; Russia Zone 2. (3 hours ahead of GMT.)
it
Iran Time. (3.5 hours ahead of GMT.)
zp4
Russia Zone 3. (4 hours ahead of GMT.)
zp5
Russia Zone 4. (5 hours ahead of GMT.)
ist
Indian Standard Time. (5.5 hours ahead of GMT.)
zp6
Russia Zone 5. (6 hours ahead of GMT.)
nst
North Sumatra Time. (6.5 hours ahead of GMT.) Note that the abbreviation NST is also used for Newfoundland Stanard Time.
sst
South Sumatra Time; Russia Zone 6. (7 hours ahead of GMT.) Note that SST is also Swedish Summer Time.
wast
West Australian Standard Time. (7 hours ahead of GMT.)
wadt
West Australian Daylight Time. (8 hours ahead of GMT.)
jt
Java Time. (7.5 hours ahead of GMT.)
cct
China Coast Time; Russia Zone 7. (8 hours ahead of GMT.)
jst
Japan Standard time; Russia Zone 8. (9 hours ahead of GMT.)
kst
Korean Standard Time. (9 hours ahead of GMT.)
cast
Central Australian Standard Time. (9.5 hours ahead of GMT.)
cadt
Central Australian Daylight Time. (10.5 hours ahead of GMT.)
east
Eastern Australian Standard Time. (10 hours ahead of GMT.)
eadt
Eastern Australian Daylight Time. (11 hours ahead of GMT.)
gst
Guam Standard Time; Russia Zone 9. (10 hours ahead of GMT.)
kdt
Korean Daylight Time. (10 hours ahead of GMT.)
nzt
New Zealand Time. (12 hours ahead of GMT.)
nzst
New Zealand Standard Time. (12 hours ahead of GMT.)
nzdt
New Zealand Daylight Time. (13 hours ahead of GMT.)
idle
International Date Line East. (12 hours ahead of GMT.)

Table of Contents


Footnotes

[1] Keytabs were called srvtabs in Kerberos V4.

[2] ank was the short form of the equivalent command using the deprecated kadmin5 database administrative tool. It has been kept