[Serusers] error revisited: I won't send a reply for ACK!!

Java Rockx javarockx at gmail.com
Wed Feb 23 13:17:29 CET 2005


I had this problem just a while ago. It was report to me, from Richard
I think, that somewhere in my ser.cfg an ACK was hitting an
sl_send_reply() which is incorrect.

ACK messages must hit a t_relay() to avoid this message.

Regards,
Paul


On Wed, 23 Feb 2005 11:54:25 +0100, Roel van Dijk <roel at almende.com> wrote:
> 
> Here's my setup:
> 
>   NATed UAs  --  firewall SER/RTPProxy (bridging mode) -- internet
> 
> I'm using a slightly altered version of the 'alg.cfg' that comes with
> the nathelper module.
> 
> I'm trying to call a UA inside my network from the internet using a
> public iptel.org account. Here's the trace of the SIP messages:
> 
>   UA1            firewall         iptel
>    |                | <--INVITE--   |
>    |                |  --trying-->  |
>    | <--INVITE--    |               |
>    |   --trying-->  |               |
>    |  --ringing-->  |               |
>    |       --OK-->  |               |
>    |                |      --OK-->  |
>    |                | <--ACK--      |
>    |               ACK              |
>    |               ACK              |
>    |               ACK              |
>    |                |               |
> 
> If we look at the ACK that comes back from Iptel, we see that the IP
> address of UA1 is missing, and therefore the routing fails, and never
> leaves the SER on the firewall (obscured IP addresses, but given a
> name):
> 
> U IPTEL.IP.ADDRESS:5060 -> FIREWALL.PUBLIC.IP.ADDRESS:5060
>   ACK sip:126 at FIREWALL.PUBLIC.IP.ADDRESS:5060 SIP/2.0..Record-Route:
> <sip:IPTEL.IP.ADDRESS;ftag=2664746953;lr=on>..Content-Length:
> 0..Contact: <sip:rdvdijk at HOME.PUBLIC.IP.ADDRESS:5060;nat=yes>..Call-ID:
> C8E48A38-6C23-42AB-9EF1-6213B2DF4CD0 at 192.168.0.2..Max-Forwards:
> 16..CSeq: 2 ACK..From:<sip:rdvdijk at iptel.org>;tag=2664746953..Route:
> <sip:FIREWALL.PUBLIC.IP.ADDRESS;ftag=2664746953;lr=on>..To:
> <sip:126 at my.realm>;tag=947fb3ad8fdd13a6..User-Agent:
> SJLabs-SJphone/1.30.235d..Via: SIP/2.0/UDP
> IPTEL.IP.ADDRESS;branch=0..Via: SIP/2.0/UDP
> 192.168.0.2:5060;rport=5060;received=HOME.PUBLIC.IP.ADDRESS;branch=z9hG4
> bKc0a800020131c9b1421c4c560000318a000000bc..P-hint:
> rr-enforced..P-NATed-URI: YES..P-RTP-Proxy: NO..P-Marked-Contact:
> YES..P-Behind-NAT: Yes....
> 
> As we see, the UA1's local IP address is nowhere to be found in the ACK
> coming back from Iptel. The other local IP address from my the
> iptel-account can be found (192.168.0.2). What we do see is: Route:
> <sip:FIREWALL.PUBLIC.IP.ADDRESS;ftag=2664746953;lr=on>, and the ACK is
> routed back to the SER a few times until I get this message in my logs:
> 
>   Warning: sl_send_reply: I won't send a reply for ACK!!
> 
> When I hang up both sides, I see the same behaviour for the BYE message,
> which is routed back to the SER itself as well.
> 
> So, what is my problem?
> 
> Roel van Dijk
> 
> PS config files can be supplied if needed, but it looks very much like
> the original alg.cfg, no serious changes as far as I can see.
> 
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>




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