SSH port forwarding was set up on the Solar server; the only way the University of Warwick Firewall would allow VNC access. SSH establishes an encrypted connection from mypc (the client) to a remote system, Solar (the server). Forwarding and tunnelling operate as channels within that link. So once there is an established SSH link (similar to a direct cable connection with SSH endpoints as mypc and Solar, on top of which other connections can be layered). Tunnelled connections can have different start and end points, using the SSH link as part of their connection. For example, if Computer B is in use and an SSH connection is made to Computer C, it is possible to establish a forwarded port so that for instance, Port 8000 on Computer B forwards to Port 80 on Computer C. If one then connects to localhost:8000 (localhost being default for Computer B), the ultimate connection is to Computer C:80, with the traffic going through the encrypted SSH link. The remote end is not limited to be Computer C if the remote endpoint is set to be, for example, D:21 (port 21, File Transfer Protocol), then connecting to localhost:8000 connects to D:21. The connection from Computer B to Computer C is encrypted, but from Computer C to D the link is unencrypted. Furthermore it is possible to connect from a Computer A to Computer B in another unencrypted link, but end up at D:21, through the current outlined setup.
VNC, Virtual Network Computing is a piece of remote control software enabling the user to view and interact with another computer desktop (the VNC server) via the program VNC Viewer. One of the key advantages of VNC is that the two computers in interaction do not have to be using the same operating system.
Written by Jonathan Holmes