OnionCat creates a transparent IP layer on top of Tor hidden services. It transparently transmits any kind of IP-based data through the Tor network on a location hidden basis. You can think of it as a point-to-multipoint VPN between hidden services.

OnionCat is a stand-alone application which runs in userland and is a connector between Tor and the local OS. Any protocol based on IP, such as UDP or TCP, can be transmitted.

OnionCat supports IPv6; native IPv4 forwarding, though still available, is deprecated: the recommended solution for IPv4 forwarding is to build a IPv4-through-IPv6 tunnel through OnionCat.