I am trying to telnet from Ubuntu server (running Maverick) on ec2 to another machine I have set up not on ec2 - we'll call it "server-x". Server-x is running an imap server and I am trying to test connectivity to it.
The two machines are connected via vpn. I can ping from the ec2 machine to server-x no problem. On another machine also on the vpn but also not on ec2 I can telnet to server-x without issue so it is accepting incoming connections on that port.
But when I run telnet from the ubuntu instance to server-x I get :
ubuntu@ip-10-111-11-11:~$ telnet 184.108.40.206 9143 Trying 220.127.116.11... telnet: Unable to connect to remote host: Connection refused
Other telnets work like this:
ubuntu@ip-10-111-11-11:~$ telnet imap.gmail.com 993 Trying 18.104.22.168... Connected to gmail-imap.l.google.com. Escape character is '^]'.
I have disabled ufw on the ubuntu machine. Is there anything else that can be blocking this outgoing connection? I tried adding the outgoing port to iptables but I'm not certain I'm doing that right.
Update: The service running on server-x is an imap server. When I changed it to use the traditional imap port 143 - the ubuntu machine can now telnet without problem. Why can it not telnet out on 9143?
I'm pretty sure 9143 is open and listening on server-x, when I run netstat:
netstat -an |grep 9143 tcp46 0 0 *.9143 *.* LISTEN tcp4 0 0 *.9143 *.* LISTEN