[Serusers] Is STUN protocol usable behind firewall?

Arnd Vehling av at nethead.de
Sat Feb 21 09:18:38 CET 2004


the STUN's procolls aim is to discover behind which kind
of NAT device you are. Behind a firewall it will usually
tell you that youre behind a "blocked" connection type
because a "real" firewall tends to have a strict ruleset
which will prevent the incoming RTP/UDP voice stream to get
through it.

If you have a firewall setup the only clean solution
is to install a SIP aware proxy either on the firewall
or install a seperate SIP (+RTP/UDP) forwarding proxy
in the DMZ.

-- Arnd

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