If you are behind a firewall which forbids you to use some useful ports, and if you can create an SSH outside, to the “internet cloud”, here is your solution.

• Tunnel Part

On Windows:

On Unix-like:

ssh -D <tunnel-entrance port> username@server-ssh.com (to be verify these options)

• Application Configuration Part

In IE or in Firefox (preferrable to configure with IE, because some other apps use the conf of IE), set Socks: localhost and the port is the port you set for the tunnel, in the photo on the right.

In Yahoo! Messenger as well as other apps such as µtorrent, you choose Socks 5 as proxy and localhost:<tunnel-entrance port>

@ To whom at INSA de Rennes, the port 995 as well as 21 and some other common ports but not 22 do not necessite the proxy of INSA. (I will verified this method this Wednesday, what I wrote here is based on theory only :p )

Brief Explanation: After opening an SSH connection, Putty will listen on any defined Source Port (which I call Local Port) and it acts as a local proxy pass all connection through the SSH server, the SSH server then forward to other servers with the appropriate ports, this is enabled by the AllowTcpFowarding option of OpenSSH.

Further Info:

pop3s           995/tcp    pop3 protocol over TLS/SSL (was spop3)
pop3s           995/udp    pop3 protocol over TLS/SSL (was spop3)