MIT Kerberos Documentation


Trace logging

Most programs using MIT krb5 1.9 or later can be made to provide information about internal krb5 library operations using trace logging. To enable this, set the KRB5_TRACE environment variable to a filename before running the program. On many operating systems, the filename /dev/stdout can be used to send trace logging output to standard output.

Some programs do not honor KRB5_TRACE, either because they use secure library contexts (this generally applies to setuid programs and parts of the login system) or because they take direct control of the trace logging system using the API.

Here is a short example showing trace logging output for an invocation of the kvno command:

shell% env KRB5_TRACE=/dev/stdout kvno krbtgt/KRBTEST.COM
[9138] 1332348778.823276: Getting credentials user@KRBTEST.COM ->
    krbtgt/KRBTEST.COM@KRBTEST.COM using ccache
[9138] 1332348778.823381: Retrieving user@KRBTEST.COM ->
    FILE:/me/krb5/build/testdir/ccache with result: 0/Unknown code 0
krbtgt/KRBTEST.COM@KRBTEST.COM: kvno = 1



KDC has no support for encryption type while getting initial credentials


credential verification failed: KDC has no support for encryption type

This most commonly happens when trying to use a principal with only DES keys, in a release (MIT krb5 1.7 or later) which disables DES by default. DES encryption is considered weak due to its inadequate key size. If you cannot migrate away from its use, you can re-enable DES by adding allow_weak_crypto = true to the [libdefaults] section of krb5.conf.

Seen in: clients


Cannot create cert chain: certificate has expired

This error message indicates that PKINIT authentication failed because the client certificate, KDC certificate, or one of the certificates in the signing chain above them has expired.

If the KDC certificate has expired, this message appears in the KDC log file, and the client will receive a “Preauthentication failed” error. (Prior to release 1.11, the KDC log file message erroneously appears as “Out of memory”. Prior to release 1.12, the client will receive a “Generic error”.)

If the client or a signing certificate has expired, this message may appear in trace_logging output from kinit or, starting in release 1.12, as an error message from kinit or another program which gets initial tickets. The error message is more likely to appear properly on the client if the principal entry has no long-term keys.


kprop: No route to host while connecting to server

Make sure that the hostname of the slave (as given to kprop) is correct, and that any firewalls between the master and the slave allow a connection on port 754.


kprop: Connection refused while connecting to server

If the slave is intended to run kpropd out of inetd, make sure that inetd is configured to accept krb5_prop connections. inetd may need to be restarted or sent a SIGHUP to recognize the new configuration. If the slave is intended to run kpropd in standalone mode, make sure that it is running.


kprop: Server rejected authentication (during sendauth exchange) while authenticating to server

Make sure that:

  1. The time is synchronized between the master and slave KDCs.
  2. The master stash file was copied from the master to the expected location on the slave.
  3. The slave has a keytab file in the default location containing a host principal for the slave’s hostname.