SecureShellTunneling

Port Forwarding

When you want to just forward a specific port locally to a remote port.

This example will create a local port 9999 that will be forwarded to the remote host webbserver.umiacs.umd.edu and its port 8000 through the host openlab.umiacs.umd.edu.

• ssh -NfL 9999:webserver.umiacs.umd.edu:8000 openlab.umiacs.umd.edu

This example will create a local port 13389 that will be forwarded to a remote host that is running a RDP client like Windows XP or Windows Vista through the host openlab.umiacs.umd.edu

• ssh -L 13389:my-desktop.pc.umiacs.umd.edu:3389 openlab.umiacs.umd.edu

Socks Proxy

SSH can also tunnel all traffic coming into a certain port through a SOCKS v5 proxy. Many browsers and some operating systems can be setup to then connect to this proxy to allow them again to look like they are coming from the host name you specify in your SSH command.

• ssh -ND 7777 openlab.umiacs.umd.edu

Please note, that when you configure proxy settings for a browser or your whole operating system all the traffic for that browser or in case your OS all your traffic will be sent through the proxy. This can have performance implications.

Port Forwarding with PuTTY

Windows users can achieve the same types of tunnels using PuTTY or a similar SSH client. In PuTTY, the port forwarding configuration dialogue can be found under "Connection>SSH>Tunnels".

This will create a local port 3889 that is attached to the remote host clipsm00.umiacs.umd.edu on its port 8000.