Desktop Remote Software (adapt TightVNC?)

Hi, we are looking for a Desktop Remote Software. What we need is an easy way to connect people together. We think about Tight VNC and want to adapt it, with a kind of handshaking... Scenario: - Server side: you start the program, the program suggests an access code e.g. 4711 - the viewer starts the program and types in 4711 and will be connected through the system. Is there a way to have a server app doing this? It would be great do have this via TightVNC others are nice too ;-) Thanks and looking forward for your bids. Bye Arndt