Probabilistic NAT Traversal

With the Probabilistic NAT Traversal project, we want to significantly improve the ability of users to directly connect with each other. For establishing a peer to peer (p2p) network among regular internet users, unhindered connectivity is anything but self-evident. Today consumer devices are often not directly reachable via the internet but quite often are behind a so called NAT delivering only indirect internet connectivity. There are several methods to reach peers who are behind a NAT, but there are as many reasons those existing methods might fail. Manual configuration for example, as it is possible for example with home routers, often does not work for mobile devices like mobile phones. We will implement a new way of NAT traversal that we think of being independent from the existing network configuration, and does not require a third party with a direct internet connection helping two peers to connect to each other. Existing NAT traversal methods using third parties which are permanently required for communication. Our Probabilistic NAT traversal method does require some third party only at the beginning of the communication. The selection of third parties to start the connection establishment is based on previous work from the Layer-2-Overlay project. Probabilistic NAT Traversal will greatly improve the connectivity of GNUnet and other P2P networks that adopt it.