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As the title says, what is the difference between UDP hole punching and STUN?

Or is it the same?

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closed as not a real question by ChrisF, Ƭᴇcʜιᴇ007, terdon, 8088, Dennis Feb 18 '13 at 3:22

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No, they are different, but it would probably be easier to read the two wikipedia articles, than it have it explained here. en.wikipedia.org/wiki/STUN en.wikipedia.org/wiki/UDP_hole_punching –  Paul Feb 17 '13 at 21:18

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up vote 1 down vote accepted

hole punching and STUN are quite different things.

STUN will allow a system to work out what its external IP address is (if, as is common, it is located behind a NATing firewall or equivalent). It is really of use where the IP address of the Internet connection is dynamically assigned.

[UDP] hole punching allows a mapping from a real world IP address to a specific box behind a NATing firewall - This is a security thing, but much more importantly required because of the 1:many relationship NAT introduces - so the NATing router needs to know which client to send the packet too. [ For responses to regular traffic it keeps a lookup table of associations between the From IP, Dest IP and ports used (and related ports if its doing its job well) ]

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