SSH Tunnels

Without over-complicating things, the above process may be blocked by a firewall. As a result an alternative route for the information transfer must be provided. This process is sometimes called tunnelling and one means is using SSH , the Secure SHell.

The user logs into the remote machine (in our case the database) over SSH with the additional ``Tunnel X Requests'' option. This creates an encrypted channel within SSH which may be used for the above transaction. Once the tunnel is initiated you need only change the display address from directly accessing the X server (eg helge.ucd.ie:0.0) to use the SSH tunnel (usually eg localhost:11.0 ¹².