# MIT Kerberos Documentation

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# Troubleshooting

## 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
        FILE:/me/krb5/build/testdir/ccache
    [9138] 1332348778.823381: Retrieving user@KRBTEST.COM ->
        krbtgt/KRBTEST.COM@KRBTEST.COM from
        FILE:/me/krb5/build/testdir/ccache with result: 0/Unknown code 0
    krbtgt/KRBTEST.COM@KRBTEST.COM: kvno = 1

## List of errors

### Frequently seen errors

1. KDC has no support for encryption type while getting initial credentials
2. credential verification failed: KDC has no support for encryption type
3. Cannot create cert chain: certificate has expired

### Errors seen by admins

1. kprop: No route to host while connecting to server
2. kprop: Connection refused while connecting to server
3. kprop: Server rejected authentication (during sendauth exchange) while authenticating to server

#### 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.

#### 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 replica KDC (as given to kprop) is correct, and that any firewalls between the primary and the replica allow a connection on port 754.

#### kprop: Connection refused while connecting to server

If the replica KDC 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 replica 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 primary and replica KDCs.
2. The master stash file was copied from the primary to the expected location on the replica.
3. The replica has a keytab file in the default location containing a `host` principal for the replica’s hostname.