Domain Controller - AD Core - Kerberose Authentication Status

Kerberos is a network authentication protocol designed to provide secure authentication for client-server applications. It was developed by MIT in the 1980s and is named after the mythical three-headed dog, Cerberus.

How Kerberos Works:

1. Key Distribution Center (KDC): This is the heart of Kerberos and consists of:

   • Authentication Server (AS): Authenticates users initially.
   • Ticket Granting Server (TGS): Issues tickets that allow users to access services.
   • Kerberos Database: Stores user credentials.

2. Authentication Process:

   • Initial Authentication: The user sends their credentials to the AS, which verifies them and issues a Ticket Granting Ticket (TGT).
   • Service Request: The user presents the TGT to the TGS to get a service ticket for the desired service.
   • Service Access: The user presents the service ticket to the service server to gain access.

Troubleshooting Kerberos Authentication Issues

When troubleshooting Kerberos issues, consider the following steps:

1. Check Time Synchronization: Ensure all devices in the network have synchronized clocks. Kerberos relies heavily on timestamps.

2. Verify DNS Settings: Incorrect DNS settings can cause Kerberos authentication failures. Ensure DNS servers are accessible and correctly configured

3. Inspect Kerberos Tickets:

   • Use the klist command to view and purge expired tickets.
   • Ensure the Service Principal Names (SPNs) are correctly set using the setspn command

4. Analyze Logs:

   • Check the System event log for errors related to Kerberos, KDC, LsaSrv, or Netlogon.
   • Look for failure audits in the Security event log on the target server