Tunneling Through Firewall: An Introduction to Port Forwarding

Use Secure Shell (SSH) to establish safe, encrypted internet connections through a firewall. With this method, you don't have to open additional ports through your firewall in order to access external email accounts, access usenet newsgroup servers, and multimedia streams, which leaves your internal network more secure. This allows means you don't have to worry about accidentally surfing to a restricted site (which raises red flags in most corporate environments), and can access sites that have been mistakenly blocked by over-zealous monitoring software. Traffic cannot be analyzed for content by sniffers or packet inspection software because of the encryption.

Access to a Server
You will need access to a server running Secure Shell on the other side of the firewall. If you are connecting from inside your company's firewall, you could run OpenSSH (an open source SSH server) from your home computer or that of a friend. Installing and configuring an SSH server is beyond the scope of this article, but good documentation exists for OpenSSH on its home site. Just make sure that you open a port through any router or personal firewall for SSH traffic. The default is port 22, but you can use any available TCP/IP port. Alternatively, there are some sites that will give you a free shell account on their server running SSH. SilenceIsDefeat.org will give you one for $1.00 if you use paypal (and signing up is then instant), or the cost of a $0.39 stamp if you register through the mail. Finally, if you pay for a commercial web host, many of them allow SSH connections to their servers.