A system for audio signalling based NAT Traversal

Mobile users often connect through WiFi access points and frequently find themselves behind NATs that are built into common off-the-shelf home access points or enterprise wireless deployments. Punching a hole through the NATs to establish a P2P connection can be a challenging task for lay users. We present our system, ANT, that utilizes Audio signaling for NAT Traversal. With ANT, unlike other NAT traversal approaches, two mobile clients can establish a direct connection with minimal user intervention and without connecting to an intermediate server. ANT uses UPnP to obtain configuration information for NAT traversal which is then encoded using different audio frequencies and converted to audio sounds that are transmitted through the users´ phones. Upon receiving the audio samples through the phone, the remote client converts them back into NAT traversal configuration data. Error correction is added to enhance the reliability of ANT and eliminate the need for retransmissions. Experimental results show that a TCP connection can be swiftly established between mobile clients behind NATs with no manual configuration, even in existence of heavy noise. We believe that ANT can be proved to be a simple, yet practical scheme for NAT traversal, which is as simple as dialing a phone number.