After more 1 000 000 (one million) views on forum for 1.5.0.x development versions... and 1.6.1.0, 1.6.3.0-dev versions A new stable version, UltraVNC 1.6.4.0 and UltraVNC SC 1.6.4.0 have been released: https://forum.uvnc.com/viewtopic.php?t=38095 Feedback is welcome
If you have any linux/unix machine acting as a NAT, then you probably don't need encryption at all. Alll you need is to start ssh, with port forwarding. All communication is encrypted, and it also helps avoiding too restrictive firewalls.