2009/2/27 Nils Ohlmeier <lists@ohlmeier.org>

Hi Samuel,

> I have seen lots of default config files where in the reply route only
> after checking the message (client_nat_test(1)) fix_nated is called.
> Why is not called when the NAT flag is set upong lookup_XX?

because the Registrar module takes already care of setting everything up
correctly when lookup() is being called.

But, as far as I know, only in the called direction. If the called party is registered and behind NAT the lookup will indeed set the destination to the "public" side of the NAT. I was more interested in "rewriting" the Contact for the 200 OK because otherwise we find the classical lost of ACK and call drop after 2x-3x seconds

> In ser-oob I think the reply_route should include the case of a user
> called behind a NAT and the reply is not fixed due to some router in
> the middle. Will it hurt including fix_nated_contact in the case of
> checking the flag?

I'm not entriely sure that I get what mean/complain about.
When I take a look at the latest ser-oo.cfg from CVS Head
http://cvs.berlios.de/cgi-bin/viewcvs.cgi/ser/sip_router/etc/ser-oob.cfg?revision=1.46&view=markup
I see in the REPLY_ROUTE a nat_uac_test("12) call and a
fix_nated_contact() call afterwards. So the Contact of the B (called)
party should be fixed if he is located behind NAT.

But nat_uac_test will only check for private addresses on Contact, isn't it?
Let me try to explain with a message exchange

---INVITE--> a.b.c.d:61000
<--200OK-- source=a.b.c.d:61000 but Contact: a.b.c.d

so ACK will be sent to a.b.c.d:5060 (deafult SIP port) instead of the "nated" port 61000.

I know it's some ALG in the router but I was just wondering whether checking the natflag in the onreply route and calling fix_nated_contact would help in this case or it would cause other issues.

Greetings
Nils