Connecting Mac to VPN server securely and for free
I would like to set up a VNC connection between several machines. Primarilly having a Mac as a client and Windows as a server. The task is to be able to control windows machines using VNC/remote desktop protocols but to have it for free (opensource client and server) and secure (encrypted channel).
There are several commercial possibilities, e.g. RealVNC. It does this and having both client and server from RealVNC enables encryption on the channel. Unfortunatelly RealVNC is not for free. In the opensource space I cannot find similar combination. There are several Mac clients, but only few support encryption (via different ways). There are several win servers, but few support encryption AND are compatible with the clients. At the end of the day I am (yet) unable to have a Win server and a Mac client connected together using encrypted channel. Insecurely it is ok. There are several possible variants to do it and they work fine.
Have anybody dealt with a similar problem and found a solution? It would be appreciated if the one can share which combination won.
There is a way of using VPN and tunnel VNC via it. But this requires additional infrastructure (keys, servers, clients, etc.) in order to work. Looking for a simpler variant first.
Thanks
MacBook Pro with Retina display, OS X Mountain Lion (10.8.2)