New subject: [OpenSER-Users] NAT question

8 Aug 2007


      Hi Bogdan,
I understand that 200 OK should not be fixed by proxyA. Maybe what I
don't understand is what nat_uac_test("2") does and when to use it.
Following is an example where 
clientA = demo1@altecnet.gr
clientB = sip_test_1@i-call.gr
proxyA = 213.5.43.4
proxyB = 213.5.43.134
When proxyA goes in the onreply_route for the 200 OK, nat_uac_test("23")
returns true (I guess because of the "2" flag) and proxyA fixes the
contact again which is wrong. So, would it be safe to use
nat_uac_test("23") for the requests and nat_uac_test("21") for the
replies? I am afraid this would break the simple case with 2 NATed
clients and only one proxy:
clientA ------> proxyA ------> clientC
thank you for your help
George
#
U 2007/08/08 10:11:34.233164 213.5.43.134:5060 -> 213.5.43.4:5060
SIP/2.0 200 Ok.
Via: SIP/2.0/UDP 213.5.43.4;rport=5060;branch=z9hG4bK322.eea78413.0.
Via: SIP/2.0/UDP
192.168.1.39;received=213.5.17.226;rport=5060;branch=z9hG4bKc0a801270000
002c46b96cbb000000a000000087.
Record-Route: sip:213.5.43.134;lr=on;ftag=109517115931019.
Record-Route: sip:213.5.43.4;lr=on;ftag=109517115931019.
From: "222" sip:demo1@altecnet.gr;tag=109517115931019.
To: sip:sip_test_1@i-call.gr;tag=0r8u9ziv3g.
Call-ID: 000029DD-5407-0000-3452-00006A3B0000@192.168.1.39.
CSeq: 2 INVITE.
Contact: sip:sip_test_1@213.5.17.236:5060;transport=udp;line=9yt55o5b.
User-Agent: snom190-3.56w.
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE,
PRACK, MESSAGE, INFO.
Allow-Events: talk, hold, refer.
Supported: timer, 100rel, replaces.
Content-Type: application/sdp.
Content-Length: 208.
.
v=0.
o=root 1592588598 1592588598 IN IP4 213.5.17.236.
s=call.
c=IN IP4 213.5.17.236.
t=0 0.
m=audio 10116 RTP/AVP 8 101.
a=rtpmap:8 pcma/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
#
U 2007/08/08 10:11:34.234013 213.5.43.4:5060 -> 213.5.17.226:5060
SIP/2.0 200 Ok.
Via: SIP/2.0/UDP
192.168.1.39;received=213.5.17.226;rport=5060;branch=z9hG4bKc0a801270000
002c46b96cbb000000a000000087.
Record-Route: sip:213.5.43.134;lr=on;ftag=109517115931019.
Record-Route: sip:213.5.43.4;lr=on;ftag=109517115931019.
From: "222" sip:demo1@altecnet.gr;tag=109517115931019.
To: sip:sip_test_1@i-call.gr;tag=0r8u9ziv3g.
Call-ID: 000029DD-5407-0000-3452-00006A3B0000@192.168.1.39.
CSeq: 2 INVITE.
Contact: sip:sip_test_1@213.5.43.134:5060;transport=udp;line=9yt55o5b.
User-Agent: snom190-3.56w.
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE,
PRACK, MESSAGE, INFO.
Allow-Events: talk, hold, refer.
Supported: timer, 100rel, replaces.
Content-Type: application/sdp.
Content-Length: 208.
P-hint: NATed reply.
.
v=0.
o=root 1592588598 1592588598 IN IP4 213.5.17.236.
s=call.
c=IN IP4 213.5.17.236.
t=0 0.
m=audio 10116 RTP/AVP 8 101.
a=rtpmap:8 pcma/8000.
a=rtpmap:101 telephone-event/8000.
a=fmtp:101 0-15.
a=sendrecv.
...
-----Original Message-----
From: Bogdan-Andrei Iancu [mailto:bogdan@voice-system.ro] 
Sent: Wednesday, August 08, 2007 9:50 AM
To: Papadopoulos Georgios
Cc: users@openser.org
Subject: Re: [OpenSER-Users] NAT question
Hi George,
each proxy should fix what it detects. ProxyA will take care 
of the traffic related to A (since it detects A as NATed) and 
ProxyB should take care of traffic for B (as it sees B as 
nated). So, the 200 OK must be fixed only by proxyB.
Regards,
bogdan
Papadopoulos Georgios wrote:
...
Hello all,
I need some advice from all you NAT experts. Assume that we
have two
...
OpenSER proxies serving two different domains and they both use 
nathelper. Also assume that their configuration is
identical and looks
...
roughly like:
route {
...
        record_route();
    if (nat_uac_test("23")) {
            if (method!="REGISTER" &&

!is_present_hf("Record-Route")) {
                    fix_nated_contact();
                }
        }
    t_on_reply("1");

}
onreply_route[1] {
        if (nat_uac_test("23")) {
                fix_nated_contact();
        };
}
clientA and clientB are both behind NAT. clientA@domainA 
mailto:clientA@domainA sends an INVITE to clientB@domainB 
mailto:clientB@domainB through proxyA:
clientA@domainA mailto:clientA@domainA  -----> ProxyA
-----> ProxyB
...
------> clientB@domainB mailto:clientB@domainB
ProxyA detects that clientA is behind NAT and fixes the contact. 
ProxyB finds the Record-Route header, so it does not fix
the contact.
...
My question is about how to handle the 200 OK. With this
configuration
...
both proxies detect that clientB is behind NAT and the contact gets 
fixed twice. Is there a way to avoid this?
thank you
George
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RE: [OpenSER-Users] NAT question