Dave’s Blog

Did you ever have a situation where you needed to access a website that had an IP restriction in place? I recently had a situation where I needed to access the web via my university connection (due to IP restrictions placed on accessing databases of research papers). They do not have a VPN setup so it is hard to do this off-campus.

I do however have access to a linux machine on campus. I am familiar with port forwarding using SSH but I had never used it to actually tunnel web traffic using a web browser on Windows. Turns out it is surprisingly easy!

The ssh command to use is:

ssh -C2qTnN -D 8080 username@remote_host

This command sshes to the remote_host, and creates a tunnel on your localhost, port 8080. Note that you need to have private key authentication already set up for this host - it will not work with password authentication.

The description of the switches are (from the ssh man page):

• -C : Compression
• -2 : Use SSHv2
• -q : quiet!
• -T : Disable pseuto-tty allocation
• -n : Prevents reading from stdin (you need to have private key authentication set up, to prevent password authentication)
• -N : Do not execute a remote command (or launch a shell). Just use the ssh process for port forwarding
• -D : Allocate a socket to listen on the local side. When a connection is made to this port it is located to the remote machine. Makes SSH work as a SOCKS server. Only root can forward privileged ports like this.

From here, you set up Firefox or your browser of choice to use a Socks proxy on localhost:8080. The man page says that SOCKS4 and SOCK5 should both work but I had to use SOCKS v4, SOCKS v5 did not seem to work for me.