Email Client Account Authentication Remotely

Question

Ok I have my Mail server up and running and everything works perfect locally. However, I am at a remote location trying to check my email but it's failing. I have the mail setup for Kerberos authentication / SSL for SMTP, POP & IMAP.
Now everything does work locally and I'm wondering I only opened and forwarded the ports for IMAP, POP, SMTP over SSL do I need to add just the Kerberos rule to firewall - Port 88 and forward that as well? Are there any other firewall rules I should be aware of to add to the 'Any' service.
Thank you.

Answer 1

lYes, kerbereos does listen to port 88.
(you can confirm with lsof -i4 , look for "kerbereos", and then issue same command with a -P and when you look at the same PID, you will then find the port number being listened to. The process name is krb5kdc
There is also a kerbereos administraion process just below it, it listens to ports 749 and 464.
Kerbereos at 88 is listened to at both TCP and UDP. So your firewall should enable both.
In Server Admin, you should be able to look up the logs for kerbereos to see if there are attempts to authenticate. This would tell you if your requests are reaching the server or not.