[Serusers] problems with NAT, ATA not responding to INVITEs

Greger V. Teigre greger at teigre.com
Sun May 29 10:11:53 CEST 2005


> My first problem is that when an ATA registers behinf the NAT
> firewall, the NAT flag is never set, so if doesn't get the pings
> every 30 seconds. I can manually set that flag by just having
> setflag(6) in the config file and that seems to temporarily fix that
> problem, but I can't tell that it does anything else.

An ngrep trace of the REGISTER would help. The NAT test does probably not 
catch the NATed device. I'm curious to know why.

> Outbound calls from the ATA work just fine, which they always have
> even where I had no NAT stuff in SER at all.  Inbound calls to the
> ATA get ignored my it though, this is a Cisco ATA-186.  I hooked up
> an old hub so I could get the messages using ngrep on the side with
> the NAT router and the main server, and here's what I see.

Is this AFTER you have set setflag(6) regardless of REGISTER?  If not, you 
should fix that first. If so, does Cisco's ATA-186 support symmetric SIP and 
RTP?  If not, it may not be listening on the port it send the message on. 
If it does, it may be that it is kicking it because it's not able to parse 
it. I know that some clients have problems with:
11.11.11.44:5060;x-route-tag="tgrp:lnx";branch=z9hG4bK8C9D..From
the x-route-tag (X-Lite is/was not able to parse it correctly).
Also, the lr=on can be turned off at the top of the config file.

I would suggest trying to get some debug info from the ATA.
g-)

> 7771111001 is the ATA, 7778881000 is a local phone.  11.11.11.100 is
> the SER router,
> 11.11.11.44 is the PSTN gateway initiating the call, 11.11.11.18 is
> the NAT router's public IP, and 10.0.2.3 is the ATA.
>
> SER router's ngrep:
> U 11.11.11.100:5060 -> 11.11.11.18:1387 27067 at 0:1480
>  ...k....INVITE
> sip:7771111001 at 11.11.11.18:1387;user=phone;transport=udp SI
>  P/2.0..Record-Route:
> <sip:11.11.11.100;ftag=6B826304-1A6A;lr=on>..Via: SIP/2
>  .0/UDP 11.11.11.100;branch=z9hG4bKeda1.2545.3..Via: SIP/2.0/UDP
> 11.11.11.44
>  :5060;x-route-tag="tgrp:lnx";branch=z9hG4bK8C9D..From:
> <sip:7778881000 at 11.11
>  11.44>;tag=6B826304-1A6A..To: <sip:7771111001 at 11.11.11.100>..Date:
> Thu, 26
>   May 2005 14:10:42 GMT..Call-ID:
> C7AED903-CD2611D9-8130A2A3-EEBB2457 at 11.11.
>  11.44..Supported: 100rel,timer..Min-SE:  1800..Cisco-Guid:
> 3350084827-34418
>  24217-2183397385-1128595304..User-Agent:
> Cisco-SIPGateway/IOS-12.x..Allow:
>  INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE,
> NOTIFY,
>  INFO, UPDATE, REGISTER..CSeq: 101 INVITE..Max-Forwards:
> 16..Remote-Party-ID
>  :
> <sip:7778881000 at 11.11.11.44>;party=calling;screen=no;privacy=off..Timesta
>  mp: 1117116642..Contact: <sip:7778881000 at 11.11.11.44:5060>..Expires:
> 180..A
>  llow-Events: telephone-event..Content-Type:
> application/sdp..Content-Length
>  : 506....v=0..o=CiscoSystemsSIP-GW-UserAgent 2462 1180 IN IP4
> 11.11.11.44..
>  s=SIP Call..c=IN IP4 11.11.11.44..t=0 0..m=audio 16536 RTP/AVP 18 2 0
> 100 1
>  01..c=IN IP4 11.11.11.44..a=rtpmap:18 G729/8000..a=fmtp:18
> annexb=yes..a=rt
>  pmap:2 G726-32/8000..a=rtpmap:0 PCMU/8000..a=rtpmap:100
> X-NSE/8000..a=fmtp:
>  100 192-194,200-202..a=rtpmap:101 telephone-event/8000..a=fmtp:101
> 0-16..a=
>  X-sqn:0..a=X-cap: 1 audio RTP/AVP 100..a=X-cpar: a=rtpmap:100
> X-NSE/8000..a
>  =X-cpar: a=fmtp:100 192-194,200-202..a=X-cap: 2 image u
>
>
> NAT (ATA location) ngrep:
> U 11.11.11.100:5060 -> 10.0.2.3:5060 27070 at 0:1462
>  .......&INVITE
> sip:7771111001 at 11.11.11.18:1405;user=phone;transport=udp S
>  IP/2.0..Record-Route:
> <sip:11.11.11.100;ftag=6B826304-1A6A;lr=on>..Via:
> SIP
>  /2.0/UDP 11.11.11.100;branch=z9hG4bKeda1.2545.6..Via: SIP/2.0/UDP
> 11.11.11.44:5060;x-route-tag="tgrp:lnx";branch=z9hG4bK8C9D..From:
> <sip:7778881000@
>  11.11.11.44>;tag=6B826304-1A6A..To:
> <sip:7771111001 at 11.11.11.100>..Date: Th
>  u, 26 May 2005 14:10:42 GMT..Call-ID:
> C7AED903-CD2611D9-8130A2A3-EEBB2457@
>  11.11.11.44..Supported: 100rel,timer..Min-SE:  1800..Cisco-Guid:
> 335008482
>  7-3441824217-2183397385-1128595304..User-Agent:
> Cisco-SIPGateway/IOS-12.x.
>  .Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER,
> SUBSCRIBE,
>   NOTIFY, INFO, UPDATE, REGISTER..CSeq: 101 INVITE..Max-Forwards:
> 16..Remot
>  e-Party-ID:
> <sip:7778881000 at 11.11.11.44>;party=calling;screen=no;privacy=o
>  ff..Timestamp: 1117116642..Contact:
> <sip:7778881000 at 11.11.11.44:5060>..Exp
>  ires: 180..Allow-Events: telephone-event..Content-Type:
> application/sdp..C
>  ontent-Length: 478....v=0..o=CiscoSystemsSIP-GW-UserAgent 2462 1180
> IN IP4
>   11.11.11.44..s=SIP Call..c=IN IP4 11.11.11.44..t=0 0..m=audio 16536
> RTP/A
>  VP 18 2 0 100 101..c=IN IP4 11.11.11.44..a=rtpmap:18
> G729/8000..a=fmtp:18
>  annexb=yes..a=rtpmap:2 G726-32/8000..a=rtpmap:0
> PCMU/8000..a=rtpmap:100 X-
>  NSE/8000..a=fmtp:100 192-194,200-202..a=rtpmap:101
> telephone-event/8000..a
>  =fmtp:101 0-16..a=X-sqn:0..a=X-cap: 1 audio RTP/AVP 100..a=X-cpar:
> a=rtpma
>  p:100 X-NSE/8000..a=X-cpar: a=fmtp:100 192-194,200-202..
>
> It looks like the ATA is getting the message, but just flat out
> ignoring it.  Anyone else have this problem?
>
> Brian
>
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