FortiGate does not pick up UPN from certificate
The FortiGate looks at the certificate subject alternate name (SAN) field to identify the machine/computer name. If the wrong SAN attribute is used, the FortiGate returns an empty string in the following debug output:
[448] __cert_ldap_query-UPN = ''
Subsequently, the LDAP search filter is empty, and the LDAP lookup fails:
[1718] fnbamd_ldap_init-search filter is: (&(userPrincipalName=)(!(UserAccountControl:1.2.840.113556.1.4.803:=2)))
Review the correct setting to configure on the FortiGate (set account-key-upn-san <option>
) and the SAN field to use on the certificate in FortiGate authentication configuration.