Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

A.4. Host Problems

A.4.1. Certificate Not Found/Serial Number Not Found Errors

The IdM information is stored in a separate LDAP directory than the certificate information, and these two LDAP databases are replicated separately. It is possible for a replication agreement to be broken for one directory and working for another, which can cause problems with managing clients.
Specifically, if the replication agreement between the two CA databases is broken, then a server may not be able to find certificate information about a valid IdM client, causing certificate errors:
Certificate operation cannot be completed: EXCEPTION (Certificate serial number 0x2d not found)
For example, an IdM server and replica have a function replication agreement between their IdM databases, but the replication agreement between their CA databases is broken. If a host is created on the server, the host entry is replicated over to the replica — but the certificate for that host is not replicated. The replica is aware of the client, but any management operations for that client will fail because the replica doesn't have a copy of its certificate.

A.4.2. Debugging Client Connection Problems

Client connection problems are apparent immediately. This can mean that users cannot log into a machine or attempts to access user and group information fail (for example, getent passwd admin).
Authentication in IdM is managed with the SSSD daemon, which is described in the Red Hat Enterprise Linux Deployment Guide. If there are problems with client authentication, then check the SSSD information.
First, check the SSSD logs in /var/log/sssd/. There is a specific log file for the DNS domain, such as If there is not enough information in the logs at the default logging level, then increase the log level.
To increase the log level:
  1. Open the sssd.conf file.
    vim /etc/sssd/sssd.conf
  2. In the [domain/] section, set debug_level.
    debug_level = 9
  3. Restart the sssd daemon.
    service sssd restart
  4. Check the /var/log/sssd/ file for the debug messages.