Q. What process uses Server Port 65535 and the GRE protocol?
A. The Generic Routing Protocol (GRE) is commonly used by VPN's to tunnel network traffic. The following information comes from Wikipedia
Generic Routing Encapsulation (GRE) is a tunneling protocol designed to encapsulate a wide variety of network layer packets inside IP tunneling packets. The original packet is the payload for the final packet. The protocol is used on the Internet to secure virtual private networks.