> For the complete documentation index, see [llms.txt](https://help.security.gallagher.com/knowledge-hub/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.security.gallagher.com/knowledge-hub/products/cc-software/troubleshoot/command-centre-errors/command-centre-errors-controllers-caus.md).

# Controllers causing Kerberos login messages

[Command Centre - Errors](/knowledge-hub/products/cc-software/troubleshoot/command-centre-errors.md) › Controllers causing Kerberos login messages

From **v8.50 onwards**, controllers periodically re-establish their connection to the Command Centre service using a TLS exchange. A Microsoft API facilitates the default TLS handshake, which tries to validate the Gallagher controller certificate and logs an error in the Event Viewer that appears to be a certificate validation against the Domain Controller on the active domain forest. Gallagher cannot modify this behaviour, as it is outside Command Centre application control.

The certificate involved in Gallagher controller communication is part of Gallagher's internal trust chain and is **not** meant to be included in the domain. It authenticates communications between the Gallagher controller and external entities; it is not intended for use in Kerberos or AD roles. It is generated by Command Centre and self-signed by the application server's certificate.

> **This behaviour should not pose any security threats to the end user or cause any issues in the Command Centre application.** The Event Viewer entries are informational noise, not a fault.

After installing Microsoft Security update [KB5014754: Certificate-based authentication changes on Windows domain controllers](https://support.microsoft.com/en-us/topic/kb5014754-certificate-based-authentication-changes-on-windows-domain-controllers-ad2c23b0-15d8-4340-a468-4d4f3b188f16), Windows Event Viewer will likely record Kerberos authentication failures.

![Event Viewer Kerberos authentication failure entry](https://328339335-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6bM8WhlBE9BYizPWJaPN%2Fuploads%2Fgit-blob-97d60cf77582e179e06c8bd441b11e9ed2172b5f%2FSECHUB-CCS-ERR-KERBEROS-01.png?alt=media)

## Tested workaround

> ⚠️ **Disclaimer:** The registry key below is server-level. If your server is shared, this change may impact other applications.

Testing of the registry key `CertificateMappingMethods`:

1. When `CertificateMappingMethods` is set to `0`, the Kerberos authentication failures no longer appear in the Event Viewer.
2. The controller continues to communicate normally with the server. Controller communications can still be stopped by sending an override from Command Centre, as expected.

![Registry Editor showing CertificateMappingMethods set to 0](https://328339335-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F6bM8WhlBE9BYizPWJaPN%2Fuploads%2Fgit-blob-7b7b86ac1b9d75be0b00437bb64ddc5f0b24c0c0%2FSECHUB-CCS-ERR-KERBEROS-02.png?alt=media)


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