Wednesday, October 2, 2002

Mail through SSH

sshMy mail server (and web server) are hosted by InfoVue.net (with GREAT service, by the way). InfoVue uses Digex for its presence on the Internet.

One day, while at work, I was unable to connect to my mail server at InfoVue.net. This was odd because my uptime has always been very good. After using tracert, I discovered that UUNet and Digex were having some sort of communications problem. My company gets its Internet access through UUNet. Another piece of evidence proving this was the case: I could use SSH to connect to my home network (hosted by my cable modem) and my home network could connect to InfoVue.net.


So, to get around the email problem, I used Putty to connect to my home SSH Server. To make this work:
  • When setting up my Putty session, I included port forwarding of localhost:110 -> mail.erdelynet.com:110 and localhost:25 -> mail.erdelynet.com:25.
  • I edited my local hosts file (c:\winnt\system32\drivers\etc\hosts) so that "mail.erdelynet.com" was just an alias for localhost (127.0.0.1 localhost mail.erdelynet.com).


This allowed me to connect to my mail server using Outlook without having to change any settings. Once UUNet and Digex worked out their problems, I disconnected from my SSH Server and removed the "mail.erdelynet.com" entry in my hosts file and all was normal.

The key to this story is: using SSH port forwarding, you can connect to any service that your SSH Server "sees".

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