@lperoma Thank you for the detailed write-up. The detection notes made this quick to scope.
FOG 1.6 covers this as follows:
FOG Client cannot authorize. This was the real gap, and a pull request now adds it: https://github.com/FOGProject/fogproject/pull/2089. The server records each host whose client fails the handshake: since when, how many times, the source address and the reason. A new list report, Reports > Client Authentication Failures, shows them with the fix next to each one. A host leaves the list when its client authenticates again. Two reasons are recorded:
The security token does not match. Reset Encryption Data fixes this. The server cannot decrypt the client’s key. This means the certificate the server publishes for clients does not pair with its private key, so every host fails at once. A reset does not help. Running the installer with --recreate-keys issues a new pair.One case stays invisible to the server. A client that trusts a different FOG CA refuses the server’s certificate and never sends a login, so there is nothing to record. Its fog.log shows “Certificate is not from FOG CA”.
Rejected iPXE menu logins. 1.6 already records each rejected login in the audit trail, with the username and the address. Look under Reports > Audit Report.
Hosts with no contact. 1.6 stores the last check-in and the last ping for each host. Fleet Report shows the last check-in, so you can sort on it.
All of this is 1.6 only. 1.5.x does not get these changes, so your script remains the answer there until you move to 1.6.