JSTUN is a STUN (Simple Traversal of UDP (User Datagram Protocol) through NAT (Network Address Translation)) implementation. STUN provides a means for applications to discover the presence and type of firewalls or NATs between them and the public Internet. In the presence of a NAT, STUN can also be used by applications to learn the public Internet Protocol (IP) address assigned to the NAT.
There is a minor bugfix in the detection of symmetric NATs. A "JSTUN"-based STUN server is now available.
URL: "JSTUN" - Java Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translation (NAT)