A vnc-ssh example:

Situation:

Windows1 ->|Possible firewall|->|Internet|->|linuxFirewall|->WindowsServer

Install vnc server on WindowsServer

on linuxFirewall:
ssh -g -L 5900:WindowsServerIP:5900 linuxFirewallIP

On Windows 1: Load cygwin so that you have ssh
in cygwin bash shell: ssh -L 5900:127.0.0.1:5900 root@linuxFirewallIP
On windows1 Run vnc and connect to 127.0.0.1::5900

Both ssh commands give you an ssh shell. exiting these shells closes the connections


NOTE: the ssh -g command could be run on the Windows server as well and a port
forward command could be put on the linuxFirewall