[Serusers] Strange response

[Bo]

Thanks for the heading up. It's really helpful.

----- Original Message -----
From: "Jiri Kuthan" <jiri at iptel.org>
To: "Bo" <boman122 at yahoo.com>; <serusers at lists.iptel.org>
Sent: Tuesday, April 01, 2003 2:48 PM
Subject: Re: [Serusers] Strange response


> That's spec-compliant SIP behaviour (I'm not telling it is a good idea,
I'm
> just telling that's what standard mandates). SIP server sends replies to
port
> numbers advertised in Via, i.e., to 5060, and not to port number from
which
> the request came.
>
> It was too late understood in SIP WG that this was quite suboptimal. There
is
> now a bug_fix, which is symmetric signaling. That tells: if UAC likes
symmetric
> forwarding (i.e., is ready to receive at the port from which it sent), it
> needs to advertise so using "rport". UASs understanding that shall send to
> origination port number and mirror this in the rport parameter.
>
> To my knowledge, ATAs support symmetric signaling but for some reason
don't
> advertise it. SER's next release supports symmetric signaling, but you
will
> need to special-case ATAs (recognize them and enforce symmetric signaling
> even if not advertised using "rport").
>
> -Jiri
>
> ps. see
http://www.iptel.org/ietf/firewall/nat/#draft-ietf-sip-symmetric-response
>
> At 09:25 PM 4/1/2003, Bo wrote:
> >Hi,
> >
> >I have tested cisco ATA186 (private IP) with SER under different
circumstances. With Linksys and D-link router, there were no problem. But
with Lioncom ADSL router, a strange thing happened. In this case, the ATA is
having a private IP 192.168.5.2 and the SIP port number is the default 5060.
The public IP of the ADSL connection was 195.226.252.124. The following is
the traces from ngrep. As you can see, the Lioncom router forwarded (NAT)
the SIP REGISTER with port 30150 while SER sent the response back to port
5060. So the ATA couldn't receive the response at all. What maybe the
problem?
> >
> >#
> >U 195.226.252.124:30150 -> 192.168.3.29:5060
> >  REGISTER sip:sip.abc.com SIP/2.0..Via: SIP/2.0/UDP
192.168.5.2:5060..From:  <sip:6701892 at si
> >  p.abc.com;user=phone>..To:
<sip:6701892 at sip.abc.com;user=phone>..Call-ID:
<mailto:1781909739 at 1>1781909739 at 1
> >  92.168.5.2..CSeq: 1 REGISTER..Contact: *..Expires: 0..User-Agent: Cisco
ATA  v2.15 ata18x (0209
> >  27a)..Content-Length: 0....
> >#
> >U 192.168.3.29:5060 -> 195.226.252.124:5060
> >  SIP/2.0 401 Unauthorized..Via: SIP/2.0/UDP
192.168.5.2:5060;received=195.226.252.124..From:  <s
> >  ip:6701892 at sip.abc.com;user=phone>..To:
<sip:6701892 at sip.abc.com;user=phone>;tag=d907c
> >  037823644515dfe0ede38ca9976.9b53..Call-ID:
<mailto:1781909739 at 192.168.5.2..CSeq>1781909739 at 192.168.5.2..CSeq: 1
REGISTER..WWW-Authen
> >  ticate: Digest realm="sip.abc.com",
nonce="3e89f40b00000000e3fd8eedb58e5662ca62981749bb0006
> >  ", algorithm=MD5..Server: Sip EXpress router (0.8.10
(i386/linux))..Content-Length: 0..Warning:
> >   392 192.168.3.29:5060 "Noisy feedback tells: pid=10613
req_src_ip=195.226.252.124 in_uri=sip:s
> >  ip.bmx-inc.com out_uri=sip:sip.abc.com via_cnt==1"....
> >
> >Thanks,
> >
> >Bo
>
> --
> Jiri Kuthan            http://iptel.org/~jiri/
>
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