Re: NAT Traversal

[Melinda Shore <mshore@cisco.com>]

At 04:20 PM 3/3/02 +0200, Tero Kivinen wrote:
>The STUN protocol seems quite complicated, it for example does binary
>search with different timeouts to find out the lifetime discovery etc.
>It also does not implement any tunneling mechanism, and it does not
>provide protocol to give the information to the other end (to undo the
>modifications done by NAT box, both ends needs to know what
>transformations are happening). 

The intent of STUN is to allow the sending host to determine what
its "external" address is.  This is *strictly* in order to allow
protocols which make use of embedded IP addresses to function
properly.  That is to say, a host placing an H.323 call can use STUN
to determine the address/port tuples at which media channels will
appear to the outside, allowing it to provide correct parameters to
OpenLogicalChannel commands.  STUN does not provide any traversal
capabilities, per se.

Melinda