ip tunneling question
 

My company firewall has port 110 blocked to prevent us from checking POP3 email.

I am however able to connect to my linux box at home through ssh.

Can I enable port forwarding to enable my pop3 client to send pop requests tunnelled through SSH (maybe using putty ssh client, or some other way) to connect to something on my home unix box which will remap the pop3 requests to port 110, to reach my pop3 email server out on the internet?

I take it you can connect to any port from your company to your home other than 110??

If yes the you can use ssh remote forwarding i.e ssh to listen on company localhost to use a port on your home machine to connect to your hostingprovider:110.

Connect your company outlook to localhost: [whateverport you choose]

There are so many tutorials on the web on how to do this.

Yes, this is entirely possible and quite easy to boot. However, you may want to think about sending your password plaintext across the Internet. It is one thing to POP from the ISP you receive service from, your traffic in this case generally never leaves the ISP's network (although may use local lines to arrive at the ISP). However, POPing across the Internet is a totally different scenario. Now, your plaintext password is travelling across the public Internet.

SSHing into your Linux box at home will create a secure tunnel between you and home, but then the secure tunnel stops there. The linux box (specifically the ssh daemon) then forwards the traffic in its "original" form the the destination host specified. The POP3 session is only encrypted from you to your linux box.

You said you were using PuTTY, so I can show you how to set that up specifically.

Assumptions:

Your linux box: mybox.dyndns.org
The POP3 server you are trying to get to: pop.acme.org

Replace the appropriate hostnames or IP's when you set it up.

Setup your PuTTY session as normal. In addition, PuTTY contains an "Auth" page. It is near the bottom of the left hand window.

In the "Source Port" field (near bottom of now right hand window) you will put '110' (without quotes).

In "Destination" field you will put 'pop.acme.org:110' (without quotes)

Make sure the 'dot' is in the "Local" field since this will be a local tunnel.

Go ahead and click "Add." When you connect to your linux box at home (mybox.dyndns.org) the tunnel will be enabled. Now on your machine at work, you can setup your POP3 server to 127.0.0.1 .

When your mail client at works connects to 127.0.0.1 on port 110, the traffic will be tunnelled (encrypted) to your linux box at home. It will then go out to pop.acme.org:110 via conventional (non tunnelled) means.

Keep in mind these specific instructions are for PuTTY. Command-line 'ssh' would be something like 'ssh -L 110:pop.acme.org:110 login@mybox.dyndns.org'

If you have questions, ask.

-Weaver