[asterisk-users] asterisk sees private IP address of a device behind NAT

[Antony Stone]

On Tuesday 11 July 2023 at 10:00:22, Fourhundred Thecat wrote:

> Hello,
> 
> my asterisk is working fine, I am just confused why, on the server I see
> private IP address of an endpoint

SIP is rather like FTP in that it embeds IP addresses (layer 3 of the OSI 
network model) in the protocol itself (layer 7).  I have always found it 
amazing that after we'd been struggling with this design flaw in FTP for years, 
it was decided to repeat it in RFC 2543.

It is one of the reasons why SIP through NAT is more challenging than, say, 
HTTP is, and one of its side effects is that you often see "real" (private) IP 
addresses of endpoints inside the communications when the packet source and 
destination addresses are the routed (public) versions.

Unless you experience actual problems in call setup or take-down, or things 
like one-way audio, just ignore it and accept that SIP was perhaps not as well 
designed as it could have been.


Antony.

-- 
People say that nothing is impossible, so I try to do the impossible every 
day.

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