Long story short, I can’t tunnel into port 110 from a remote site - the connection is refused. I can telnet to 110 locally but as soon as I try to come down the ssh tunnel, the wheels fall off. The firewall is off for now and POP3 works just fine locally. It’s a permissions thing, I’m sure, but what one?
The tunnel is set up with
ssh -L 11110:mailserver.foo.com:110 -l user -N mailserver.foo.com
and something as simple as
telnet localhost 11110
tanks. ssh works fine otherwise - that is, ssh -l user mailserver.foo.com gives me a terminal session on mailserver.foo.com as expected.
The problem, then, was using the remote system’s name instead of using localhost. Now to verify this works by physically leaving the net (the problem is I’m trying this from a set of machines that are on a common ethernet net - the router should be sending me out into the Internet and back but maybe not?). I’ll report back.
The frustrating thing is I could see the attempts showing up at the server and being rejected. Using tail -f /var/log/messages, the attempts to use port 110 were reported along with the error messages.
I have, however, successfully retrieved mail from the server, so I know the tunnel works. At least here at home. Tomorrow I’ll try it from the road…
As an aside, while watching /var/log/messages during testing, I happened to see:
Mar 15 23:20:20 wxsat sshd: Invalid user test from 220.127.116.11
Mar 15 23:20:24 wxsat sshd: Invalid user webmaster from 18.104.22.168
Mar 15 23:20:28 wxsat sshd: Invalid user oracle from 22.214.171.124
Mar 15 23:20:30 wxsat sshd: Invalid user library from 126.96.36.199
Mar 15 23:20:31 wxsat sshd: Invalid user info from 188.8.131.52
Mar 15 23:20:33 wxsat sshd: Invalid user shell from 184.108.40.206
Mar 15 23:20:35 wxsat sshd: Invalid user linux from 220.127.116.11
Mar 15 23:20:37 wxsat sshd: Invalid user unix from 18.104.22.168
Mar 15 23:20:39 wxsat sshd: Invalid user webadmin from 22.214.171.124
Mar 15 23:20:43 wxsat sshd: Invalid user test from 126.96.36.199
Mar 15 23:20:51 wxsat sshd: Invalid user master from 188.8.131.52
Mar 15 23:21:19 wxsat sshd: Invalid user test from 184.108.40.206
Mar 15 23:21:21 wxsat sshd: Invalid user test from 220.127.116.11
Mar 15 23:21:23 wxsat sshd: Invalid user webmaster from 18.104.22.168
Mar 15 23:21:25 wxsat sshd: Invalid user user from 22.214.171.124
Mar 15 23:21:27 wxsat sshd: Invalid user username from 126.96.36.199
Mar 15 23:21:29 wxsat sshd: Invalid user username from 188.8.131.52
Mar 15 23:21:31 wxsat sshd: Invalid user user from 184.108.40.206
Mar 15 23:21:37 wxsat sshd: Invalid user test from 220.127.116.11
Mar 15 23:21:46 wxsat sshd: Invalid user danny from 18.104.22.168
Mar 15 23:21:48 wxsat sshd: Invalid user sharon from 22.214.171.124
Mar 15 23:21:50 wxsat sshd: Invalid user aron from 126.96.36.199
Said idiot at least did me the favor of reminding me to adjust ssh to minimize break in attempts. Aren’t script kiddies fun? >:)