Unable to connect to imap via telnet remotely

Question

If I try:

telnet localhost 143

I can get access to imap

If I try

telnet server.name 143

I get

telnet: Unable to connect to remote host: Connection timed out

See output of my netstat.

netstat --numeric-ports -l | grep 143

tcp        0      0 0.0.0.0:143             0.0.0.0:*               LISTEN     
tcp6       0      0 :::143                  :::*                    LISTEN   

What does the above output mean?

Am at my wits end cannot get imap to work remotely, works perfectly with webmail on the server.

I'm accessing the server from laptop terminal remotely, and locally for localhost connection

Answer 1

The output you quote:

tcp        0      0 0.0.0.0:143             0.0.0.0:*               LISTEN     
tcp6       0      0 :::143                  :::*                    LISTEN

means that you have a program (presumably your imap server) listening on port 143 via tcp (on both IPv4 and IPv6). And the "0.0.0.0" part means it should accept connections from any source. (If it said "127.0.0.1:143" for the local address, it would mean that only local connections would be accepted.)

So, since it looks like you have the serer listening correctly, I'd first check that server.name actually resolves to the correct IP address. Can you contact any other services on that server to make sure that part works?

Assuming that that works, then the next thing I'd check would be your firewall. You might look at http://www.cyberciti.biz/faq/howto-display-linux-iptables-loaded-rules/ but you could probably start by just running:

sudo iptables -L -v

On my machine which has no firewall rules I get this:

$ sudo iptables -L -v
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

If you get something much different, the I'd take a closer look to see if that's blocking your traffic.