[asterisk-users] NAT yes

[Alex Balashov]

On 07/26/2011 09:19 AM, Flavio Miranda wrote:

> In a no natted environment if I letnat=yes on sip.conf it would
> cause some thing bad or it is irrelevant ? Anybody know ?

There is no harm unless the endpoint you are dealing with does not do 
symmetric RTP.  The nat=yes option assumes that it is okay to send RTP 
back to the source port from which it originated, irrespectively of 
what's in the SDP.  This will cause one-way audio if the endpoint 
happens to want to receive RTP on a different port than the one it is 
sending it from.

Almost all endpoints these days do symmetric RTP, though, so it's not 
a huge concern.

That said, from a methodological and aesthetic perspective, it is 
better not to break standard RFC-compliant behaviour unnecessarily. 
Thus, I would not enable nat=yes unless there really is no direct 
network and transport-layer reachability to the endpoint.

-- 
Alex Balashov - Principal
Evariste Systems LLC
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