Kerberos for Windows 3.1

Release Notes

17 November 2006

Table of Contents


Overview

MIT Kerberos for Windows (KfW) is an integrated Kerberos release for Microsoft Windows operating systems. It includes the Kerberos v4 library, Kerberos v5 library version 1.4.4, Kerberos v5 GSS API library, Kerberos 524 library, KClient API library, Leash API library, Network Identity Manager, kinit/klist/kdestroy/krb524init/ms2mit/aklog command-line credentials managers, and an in-memory credentials cache.

Terminology

Kerberos v4 (also Kerberos 4 or Kerberos version 4) and Kerberos v5 (also Kerberos 5 or Kerberos version 5) refer to versions 4 and 5 of the Kerberos protocol. A protocol is a specification for how data is transmitted on a network.

Kerberos credentials and Kerberos tickets are the same thing.


What's New in Kerberos for Windows 3.1

3.1.0

  • Improvements to the Network Identity Manager

1.                                                                              A serious memory leak has been fixed

2.                                                                              Principal names containing numbers are no longer considered invalid

3.                                                                              Locales other than en_US are now supported

4.                                                                              Arbitrary sort ordering of credentials

5.                                                                              Support for FILE: ccaches

6.                                                                              Credential properties may be selected by the user for display

7.                                                                              User selected font support

8.                                                                              Tool Tip support added to the Toolbar

9.                                                                              Identities can be added without obtaining credentials

10.                                                                          Kerberos 5 Realm editor has been added

  • A serious thread safety error in the Kerberos 5 libraries can result in premature application termination.
  • The MSLSA: ccache is disabled in WOW64 environments prior to Microsoft Windows Vista Beta 2
  • .EXE installer built using NSIS 2.18
  • .MSI installer built using WIX 2.0.4220.0

3.0.0

  • Kerberos 5 library updated to release 1.4.3.  The most important change in this release is that the Kerberos 5 libraries are safe for use in multi-threaded applications.   See the Kerberos 5 README file for details of additional changes in the Kerberos 5 version 1.4.3 distribution.
  • Kerberos 4 support is beginning to be phased out.  The default for new installations is to not obtain Kerberos 4 tickets in the Network Identity Manager or kinit.exe.
  • The Leash credential manager has been replaced by a new modular framework for identity manager called the Network Identity Manager.
    • It ships with a Kerberos 5 identity manager that manages multiple Kerberos 5 Identities and allows the user to select which one should be used as the default.
    • It ships with Kerberos 5 and Kerberos 4 plug-ins that allow users to obtain Kerberos 5 and Kerberos 4 credentials
    • An AFS plug-in is available separately from Secure Endpoints Inc. which will be incorporated into a future version of OpenAFS for Windows
    • Organizations that wish to develop their own plug-ins are encouraged to contact kfw-bugs@mit.edu
  • A new KFW Network Provider is installed to obtain tickets at login time for the default realm and store them into the user credential cache.
  • Microsoft Windows 95, 98, ME, and NT 4.0 are no longer supported
  • The aklog utility is no longer distributed.   It ships as part of OpenAFS for Windows 1.4.0.
  •  

System Requirements

Operating System

Kerberos for Windows 3.1 is designed for 32-bit versions of Windows 2000, XP, 2003, 2003 R2 or higher and WOW64 environments.

Microsoft Redistributable DLLs

The following versions or newer of several freely redistributable Microsoft DLLs are required depending on the compiler release used to build the distribution.  The MIT distribution is built using the Microsoft Visual Studio .NET 2003 C/C++ compiler:

 

Filename

    

Version

    

Description

*

mfc71.dll

 

7.10.3077.0

 

MSVS.NET 2003 MFCDLL Shared Library - Retail Version

*

msvcr71.dll

 

7.10.3052.4

 

MSVS.NET 2003 Microsoft (R) C Runtime Library

*

msvcp71.dll

 

7.10.3077.0

 

MSVS.NET 2003 Microsoft (R) C Runtime Library

 

mfc70.dll

 

7.00.9466.0

 

MSVS.NET MFCDLL Shared Library - Retail Version

 

msvcr70.dll

 

7.00.9466.0

 

MSVS.NET Microsoft (R) C Runtime Library

 

msvcp70.dll

 

7.00.9466.0

 

MSVS.NET Microsoft (R) C Runtime Library

*

psapi.dll

 

4.0.1198.1

 

Process Status Helper [not used in Windows 95/98/98SE/ME]

The KfW Installer will install the DLLs marked by an asterisk.

To see what Microsoft products ship with which version of these DLLs, you can use the DLL Help Database.

If you are not using the installer and you are missing some of these DLLs, you can download the Microsoft Redistributable Components component from the MIT Kerberos download site and manually install each missing DLL.

Note: psapi.dll is also available by itself from the Microsoft Download Center.


Installation and Configuration

Binaries

Core Binaries

 

Filename

    

Description

 

krbv4w32.dll

 

Kerberos 4 library

 

krbcc32.dll

 

Kerberos credentials cache library -- required by Kerberos 4; used by Kerberos 5 for in-memory credentials cache

 

krbcc32s.exe

 

Kerberos credentials cache -- required by krbcc32.dll

 

kclnt32.dll

 

KClient library -- required by some Kerberos 4 applications (deprecated)

 

krb5_32.dll

 

Kerberos 5 library

 

krb524.dll

 

Kerberos 524 compatibility library

 

leashw32.dll

 

Exports Ticket Init and Change Password dialogs as well as registry get/set/reset functions for managing Leash configurations.  (Used by third party applications.)

 

xpprof32.dll

 

Kerberos 5 Profile Management library (required by leashw32.dll)

 

comerr32.dll

 

Kerberos 5 Common Error Library (required by Kerberos 5 and Leash32.exe)

 

gssapi32.dll

 

GSS API for Kerberos 5

 

wshelp32.dll

 

Winsock helper used by various things

 

kinit.exe

 

command-line app to get Kerberos credentials

 

klist.exe

 

command-line app to list Kerberos credentials

 

kdestroy.exe

 

command-line app to destroy Kerberos credentials

 

k524init.exe

 

command-line app to get Kerberos 4 credentials using Kerberos 5 credentials instead of a password

 

ms2mit.exe

 

command-line app to transfer Microsoft Kerberos v5 domain credentials into the MIT Kerberos v5 credentials cache.

Network Identity Manager Binaries

netidmgr.exe

Network Identity Manager main executable.

krb4cred.dll

Provides information to Windows about which versions of libraries should be associated with netidmgr.exe.

krb4cred_en_us.dll

Kerberos 4 credentials provider plugin.

krb5cred.dll

English (US) language resources for the Keberos 4 credentials provider.

krb5cred_en_us.dll

Kerberos 5 credentials provider and identity provider plugin.

nidmgr32.dll

English (US) language resources for the Kerberos 5 credentials provider.

It is recommended that all binaries be installed into a single directory in the user's PATH. Make sure that you do not have other Kerberos binaries in your PATH.  The default location is “%ProgramFiles%\MIT\Kerberos\bin”.

Locating Kerberos Configuration Files

The simplest configuration is to put the krb5.ini, krb.con, and krbrealm.con configuration files in the Windows directory (or in the same directory as the Kerberos DLLs).  The NSIS and WIX installers search for configuration files only in the Windows directory.

Kerberos 5

Kerberos 5 needs a single configuration file: krb5.ini. You can put it in the Windows directory;  or you can put it in the same directory as the DLL; or you can point to an arbitrary file by setting the KRB5_CONFIG environment variable.

Kerberos 4

Kerberos 4 needs two configuration files, typically called krb.con and krbrealm.con. You can put these files in the same directory as the DLL and everything should work. You can also set KRB4_KRB.REALMS or KRB4_KRB.CONF to override each file. Or you can set KRB4_CONFIG to force Kerberos 4 to look for both files in a particular directory. If you do none of these, this is where Kerberos 4 will search:

  1. %NDIR%\kerb\
  2. The current directory
  3. The Windows directory
  4. The Windows system directory
  5. The directory containing the executable file for the current task
  6. The directories in the path (*)
  7. The list of directories mapped in a network
  8. %NDIR%\
  9. %ETC%\

(*) Note: If you put the files in the DLL's directory, this part of the search is what will take you there. If you have another config file earlier in the search, that will take precedence, so be careful.

Modifying Kerberos Configuration Files

IMPORTANT: The Network Identity Manager can be used to manage the Kerberos 5 and Kerberos 4 configuration files. NetIDMgr enforces a requirement that the Realm, KDC, and Realm/DNS mapping information is equivalent for both Kerberos 4 and Kerberos 5.  If this is not true for your Realms, you should not use NetIDMgr to manage the configuration files.  Instead use a text editor such as Notepad.

Kerberos 5

See the krb5.conf (MIT website)section in the Kerberos v5 System Administrator's Guide (MIT website).

Kerberos 4

It is anticipated that most sites using Kerberos version 4 on Windows also will have an existing UNIX Kerberos infrastructure. For that reason, the format of the krb.con is identical to the UNIX krb.conf and the format of krbrealm.con identical to the UNIX krb.realms. For many users, the easiest way to configure these files for use at their local sites will be to ftp the corresponding files from a local UNIX machine that is already properly configured.

The krb.con file contains configuration information describing the Kerberos realm and the Kerberos key distribution center (KDC) servers for known realms.

krb.con contains the name of the local realm in the first line, followed by lines indicating realm/host entries. The first token is a realm name, and the second is a hostname of a host running a KDC for that realm. The words "admin server" following the hostname indicate that the host also provides an administrative database server which is contacted when changing a user's password. For example:

ATHENA.MIT.EDU
ATHENA.MIT.EDU kerberos.mit.edu admin server
ATHENA.MIT.EDU kerberos-1.mit.edu
ATHENA.MIT.EDU kerberos-2.mit.edu
LCS.MIT.EDU kerberos.lcs.mit.edu admin server

If this were your krb.con file and you wanted to change the default local realm to CIT.CORNELL.EDU you would edit it to look like:

CIT.CORNELL.EDU
CIT.CORNELL.EDU kerberos.cit.cornell.edu admin server
ATHENA.MIT.EDU kerberos.mit.edu admin server
ATHENA.MIT.EDU kerberos-1.mit.edu
ATHENA.MIT.EDU kerberos-2.mit.edu
LCS.MIT.EDU kerberos.lcs.mit.edu admin server

The krbrealm.con file is the host-to-Kerberos realm translation file. This provides a translation from a local hostname to the Kerberos realm name for the services provided by that host.

Each line of the translation file is in one the following forms (domain_name should be of the form .XXX.YYY, e.g., .LCS.MIT.EDU):

        host_name kerberos_realm
        domain_name kerberos_realm

If a hostname exactly matches the host_name field in a line of the first form, the corresponding realm is the realm of the host. If a hostname does not match any host_name in the file, but its domain exactly matches the domain_name field in a line of the second form, the corresponding realm is the realm of the host.

If no translation entry applies, the host's realm is considered to be the hostname's domain portion converted to uppercase.

Using DNS Lookups for Kerberos Configuration

What is it?

DNS lookups provide Kerberos the ability to determine the Kerberos Realm that a host belongs to and to find the servers associated with a given Realm by using the Domain Name Service instead of or in addition to local configuration files.

When are DNS Lookups used?

DNS lookups are used in either of these two circumstances:

  • No krb.con file is found for Kerberos 4 or no krb5.ini file is found for Kerberos 5.
  • The krb.con file or krb5.ini file contains a command to activate DNS Lookups and the lookup cannot be answered by data found in the appropriate configuration file.

To activate DNS lookups for Kerberos 4 when the krb.con file is present, add the following line to the file as a realm-to-host entry (usually to the end):

.KERBEROS.OPTION. dns

When DNS lookups are used, the first line in the krb.con file (which would contain the default realm) may be left blank to indicate that the default realm should be determined by a DNS lookup.

To activate DNS lookups for Kerberos 5 when the krb5.ini file is present, place:

dns_lookup_kdc = true
dns_lookup_realm = true

into the [libdefaults] section. If a "default_realm" entry is not provided, a DNS lookup will be performed to determine the default realm.

What entries go into the DNS?

Host to realm lookups are performed using DNS TXT records. Example records are:

_kerberos.yclept.kermit.columbia.edu.  IN TXT "KRB5.COLUMBIA.EDU"
_kerberos.columbia.edu.                IN TXT "CC.COLUMBIA.EDU"

Realm to server lookups are performed using DNS SRV records. Example records are:

_kerberos._udp.KRB5.COLUMBIA.EDU.    IN SRV 0 0 88      yclept.kermit.columbia.edu
_kerberos._tcp.KRB5.COLUMBIA.EDU.    IN SRV 0 0 0       .
_krb524._udp.KRB5.COLUMBIA.EDU.      IN SRV 0 0 4444   yclept.kermit.columbia.edu
_kerberos-iv._udp.KRB5.COLUMBIA.EDU. IN SRV 0 0 750     yclept.kermit.columbia.edu
_kerberos-adm._tcp.KRB5.COLUMBIA.EDU IN SRV 0 0 749     yclept.kermit.columbia.edu
_kpasswd.