Does anyone has JSTUN documentation or help explain more?

Question

I am going to use STUN as my traversal NAT solution, and come across with JSTUN. While I have searched arround stackoverflow, I found this post mentioned JSTUN has its documentation inside the source: Java and Which Stun libraries i should use?

However, the source on http://javawi.de/ was broken and then I found the alternative way to download JSTUN code https://github.com/tking/JSTUN

So I am here to ask for the documentation if someone would give me, and would like to know how does it works:

1.de.javawi.jstun.test.demo.StunServer requires me to provide 2 ip and ports. In my mind, STUN server is a way to provide "hole punching" service, why does it need 2 ip and ports?

2.After run de.javawi.jstun.test.demo.DiscoveryTestDemo, it returns me the ip, what does it mean?

No route to host
java.io.IOException: No route to host
No route to host
    at java.net.PlainDatagramSocketImpl.send(Native Method)
    at java.net.DatagramSocket.send(DatagramSocket.java:625)
    at de.javawi.jstun.test.DiscoveryTest.test1(DiscoveryTest.java:96)
    at de.javawi.jstun.test.DiscoveryTest.test(DiscoveryTest.java:64)
    at de.javawi.jstun.test.demo.DiscoveryTestDemo.run(DiscoveryTestDemo.java:48)
    at java.lang.Thread.run(Thread.java:680)
java.io.IOException: No route to host
    at java.net.PlainDatagramSocketImpl.send(Native Method)
    at java.net.DatagramSocket.send(DatagramSocket.java:625)
    at de.javawi.jstun.test.DiscoveryTest.test1(DiscoveryTest.java:96)
    at de.javawi.jstun.test.DiscoveryTest.test(DiscoveryTest.java:64)
    at de.javawi.jstun.test.demo.DiscoveryTestDemo.run(DiscoveryTestDemo.java:48)
    at java.lang.Thread.run(Thread.java:680)
Network interface: en0
Local IP address: 192.168.1.23
Result: Port restricted Cone NAT handles connections.
Public IP address: 116.48.14.100

Regards,

Steve

Answer 1

This is my understanding of NAT traversal:

You have your external "Wide Area Network" IP address (WAN), which you can discover here: http://www.mywanip.com/ . This IP is exposed to the internet by your router. You also have an internal IP address, which is protected by your router. It will likely read 192.168.x.x.

Answer 2

DiscoveryTestDemo, returns your public IP and public port, as seen by the stun server you provide, and also tells you what kind of router you are behind. (this is what STUN is for)

For hole punching you will have to write your own code. UDP hole punching is easy, you can easily find resources for it. Here is a good link for TCP hole punching : http://ramonli.blogspot.in/2012/03/tcp-hole-punching-how-to-establish-tcp.html