I am planning to close off port 25 in the near future for incoming connections except from my anti-spam gateway that will be setting in front of my cpanel server. I am though concerned that some users might still be using port 25 versus 587 or 465 for smtp. The only smtp authentication i am seeing in the exim_mainlog is failed connections and standard non authenticated connections. Am a missing something? Any suggestions for tracking what ports are being used for smtp auth and from what email accounts/domains?
That thread doesn't help me at all. You seem to try to educate the user on what ports are used for what, which i already know. As explained, I'm looking for only to find out what users are using port 25 for SMTP auth only, not general connections for server to server communication.
The thread I referenced lists a couple of ways of checking for this (through CSF and with custom IPTables rules). I presume you read through the entire thread, and not just the first post? I am not aware of any other methods of tracking which IP addresses are connecting to port 25, however I will leave this thread open for others to add their input.
Thank you.
Yes I did read the whole thing and I think you are overlooking the key word here "auth". As in smtp authentication. A lot of traffic obviously flows through port 25 that isnt authenticated as its server to server communication. I am only looking to track users that are authenticated/submitting through port 25. The exim_mainlog appears to track users that fail their authentication on port 25 and the maillog keeps track of imap/pop3 connections, but for some reason I cant seem to find a record of valid smtp auths on port 25.