I've been using port 2525 as an alternative mail port for quite some time now with few problems, however, it's always thrown a nagios alert from time to time that the service is unavailable, by the time I log in or even try to telnet to the port there are no issues, nothing in the logs and no other indications of any other problem. Once in a while I will try to send mail via that port and I will get a server unavailable, retry and it's fine.
I'm just wondering if something else could be blocking./trying that port? or if it has a limit set somewhere else - other than xinetd.
- xinet limits are 100 connections, which should be tons and tons for the number of users actually using it [maybe a dozen]
- I limited proftpd to use unpriviledged ports higher than that just in case ftp users were monopolizing the port... does not appear to be the case.
- scanned for trojans etc, nadda
kinda stumped on this one as from time to time I will get a mail user complain and describe the same symptons I see... I have the same nagios monitor on port 25 & 26, they never alert, just 2525..