How to get external port from stun server

Asked Jan 14 '22 at 18:09

Active Jan 14 '22 at 18:09

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How to get external ip and port from stun server? For example Google's stun server, stun.l.google.com

So I can use that to establish P2P connection with sockets between clients behind NAT.

Currently, I can only connect to peers in local network, but I want to connect peers outside of local network with sockets.

asked Jan 14 '22 at 18:09

Sonu Mohammad

You'll need a STUN library and a service for exchanging address candidates: https://stackoverflow.com/a/8524609/104458 – selbie Jan 15 '22 at 03:17
How can I request a stun server my ip and port with sockets? I want a code implementation in Java – Sonu Mohammad Jan 15 '22 at 04:54
How to use JSTUN library? – Sonu Mohammad Jan 15 '22 at 04:55
JSTUN is the answer you seek. – selbie Jan 15 '22 at 04:56
There is no documentation for JSTUN. I am getting exceptions. Can you give a code snippet of it? – Sonu Mohammad Jan 15 '22 at 05:05
Start by compiling jstun library and the sample apps yourself and running it. Then step through it with a debugger - you'll quickly see the class hierarchy. – selbie Jan 15 '22 at 17:29
Please give a code snippet of the function that takes socket or port number and returns external ip and port. – Sonu Mohammad Jan 19 '22 at 05:10
I want to use Google's stun server, stun.l.google.com – Sonu Mohammad Jan 19 '22 at 05:11
Start with the JSTUN sample code here to run the "Discovery Test" or the "Fast Discovery Test" client code. It's all here: https://github.com/tking/JSTUN/tree/master/src/main/java/de/javawi/jstun/test/demo – selbie Jan 19 '22 at 06:22
How to get InetAddress for constructor? – Sonu Mohammad Jan 19 '22 at 06:33
Sonu. Learn how to send UDP packets first using Java's network and socket libraries. – selbie Jan 19 '22 at 06:35

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