[SR-Users] Issue with From address being modified in ACK when UAC module used version 4.1

Wed Jan 25 17:36:53 CET 2017

Hi Daniel,

Ok perfect thank you for the detailed response, I will look to test and implement!

Thank you!

Jon

________________________________
From: Daniel-Constantin Mierla <miconda at gmail.com>
Sent: 25 January 2017 16:14
To: Jonathan Hunter; Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] Issue with From address being modified in ACK when UAC module used version 4.1

The mechanism to update and restore the From header is relying on the fact that the UA sticks to the RFC requirements of not changing the values, because it using a XOR masking algorithm.

If the From is not preserved by the UA, then it screws up the update/restore for subsequent requests/replies. The newer versions have a safety check so in such case it doesn't perform the change.

The alternatives to cope with this situations are:

1) don't do auto restore -- this can be controlled by uac module parameter -- if the UA changes the From, then it doesn't expect to be the same always. I use it quite often these day, because all the UAs I have seen lately they match the dialog with From and To tags (as per RFC3261). No need to use >From URI/To URI as was required by RFC2543 (and RFC3261 has a constraint of backward compatibility).

What I do in this cases is to replace From/To only for initial requests to what I need. For all the requests within dialog I replace them with annonymous at domain.com<mailto:annonymous at domain.com>

2) rely on dialog module to keep the old and new values for From/To (instead of default one which uses the record-route parameter) -- it looks like being available on 4.1.x:

https://www.kamailio.org/docs/modules/4.1.x/modules/uac.html#uac.p.restore_dlg

Cheers,
Daniel

On 25/01/2017 16:42, Jonathan Hunter wrote:

Sorry Daniel, hit reply by mistake!

So

The initial invite shows;

From: "+44792498881474" <sip:+44792498881474 at carrier.peering.telecom.im;user=phone><sip:+44792498881474 at carrier.peering.telecom.im;user=phone>;tag=carrier.peering.telecom.im+4+c538fe37+7570d4e5

And the ACK has the resolved From domain, as in IP address and port;

From: "+44792498881474" <sip:+44792498881474 at 192.168.226.51:5080;user=phone><sip:+44792498881474 at 192.168.226.51:5080;user=phone>;tag=carrier.peering.telecom.im+4+c538fe37+7570d4e5

Although that is the case on other calls that work.

Shall I setup some debug on a lab instance and capture?

Thanks

Jon
________________________________
From: Jonathan Hunter <hunterj91 at hotmail.com><mailto:hunterj91 at hotmail.com>
Sent: 25 January 2017 15:37
To: Kamailio (SER) - Users Mailing List; miconda at gmail.com<mailto:miconda at gmail.com>
Subject: Re: [SR-Users] Issue with From address being modified in ACK when UAC module used version 4.1

Hi Daniel,

This is the initial invite from the carrier;

From: "+44792498881474" <sip:+44792498881474 at carrier.peering.telecom.im;user=phone><sip:+44792498881474 at carrier.peering.telecom.im;user=phone>;tag=carrier.peering.telecom.im+4+c538fe37+7570d4e5

________________________________
From: sr-users <sr-users-bounces at lists.sip-router.org><mailto:sr-users-bounces at lists.sip-router.org> on behalf of Daniel-Constantin Mierla <miconda at gmail.com><mailto:miconda at gmail.com>
Sent: 25 January 2017 14:28
To: Kamailio (SER) - Users Mailing List
Subject: Re: [SR-Users] Issue with From address being modified in ACK whishen UAC module used version 4.1

Hello,

is the From in incoming INVITE same as in ACK?

Cheers,
Daniel

On 25/01/2017 15:16, Jonathan Hunter wrote:
Hi Guys,

running kamailio 4.1.4 and using uac_replace_from, I am seeing a strange issue with the proxying of an ACK message back from a carrier to freeswitch on the ingress path into a network.

So its just a normal call inbound, where on outbound leg we modify the From address, on the inbound leg all remains the same.

Now after the ingress side receives the 200ok, it sends an ACK as below;

ACK sip:+441624111111 at 192.168.24.8:5080;transport=udp SIP/2.0
Via: SIP/2.0/UDP 4.4.4.4:5060;branch=z9hG4bK+7f5c8c756ae3b26a956b33b88c77c29f1+sip+3+aa6d1466
Call-ID: 8791dbd3855eeafd484f397de6e2f76e at carrier.peering.telecom.im<mailto:8791dbd3855eeafd484f397de6e2f76e at carrier.peering.telecom.im>
From: "+44792498881474" <sip:+44792498881474 at 192.168.24.8:5080;user=phone><sip:+44792498881474 at 192.168.24.8:5080;user=phone>;tag=carrier.peering.telecom.im+3+863d20a3+1b9801d2
To: "+441624111111" <sip:+441624111111 at 8.8.8.8:5080;user=phone>;tag=6rrtgNFQDNrFF
CSeq: 1 ACK
Contact: <sip:4.4.4.4:5060><sip:4.4.4.4:5060>
Route: <sip:192.168.24.8;lr=on;ftag=carrier.peering.telecom.im+3+863d20a3+1b9801d2;vsf=AAAAAAAAAAYNBgAPAAgLAgZ3UTMACgBXFUsVFwwcDkAKTwMZGh0YAA8KDkEEQ1NYC0NDXgdOFRpSHg1vbmU-><sip:192.168.24.8;lr=on;ftag=carrier.peering.telecom.im+3+863d20a3+1b9801d2;vsf=AAAAAAAAAAYNBgAPAAgLAgZ3UTMACgBXFUsVFwwcDkAKTwMZGh0YAA8KDkEEQ1NYC0NDXgdOFRpSHg1vbmU->
Content-Length: 0
Max-Forwards: 68

However kamailio changes the From address;

ACK sip:+441624111111 at 192.168.24.8:5080;transport=udp SIP/2.0
Via: SIP/2.0/UDP 109.73.69.165:5060;branch=z9hG4bKc1ce.47974fc3da2b669a78f2dcc9a057a127.0
Via: SIP/2.0/UDP 4.4.4.4:5060;rport=5060;branch=z9hG4bK+7f5c8c756ae3b26a956b33b88c77c29f1+sip+3+aa6d1466
Call-ID: 8791dbd3855eeafd484f397de6e2f76e at carrier.peering.telecom.im<mailto:8791dbd3855eeafd484f397de6e2f76e at carrier.peering.telecom.im>
From: "+44792498881474" <sip:+441444680332 at es132y$}-9><sip:+441444680332 at es132y$%7D-9>.8n?~9,*%(;zyk393;7e&C^NRone>;tag=carrier.peering.telecom.im+3+863d20a3+1b9801d2
To: "+441624111111" <sip:+441624111111 at 8.8.8.8:5080;user=phone>;tag=6rrtgNFQDNrFF
CSeq: 1 ACK
Contact: <sip:4.4.4.4:5060><sip:4.4.4.4:5060>
Content-Length: 0
Max-Forwards: 67

Causing FreeSWITCH to not recognise the request, and therefore not send an ACK.

There are no rules set against the ACK processing.

Has anyone seen this before? We dont know when it  started happening which doesnt help, I will look to setup debug on test environment but just wondered if this is an issue thats been seen before?

Many thanks in advance.

Jon

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--
Daniel-Constantin Mierla
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Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com<http://www.asipto.com>
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com<http://www.kamailioworld.com>

--
Daniel-Constantin Mierla
www.twitter.com/miconda<http://www.twitter.com/miconda> -- www.linkedin.com/in/miconda<http://www.linkedin.com/in/miconda>
Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com<http://www.asipto.com>
Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com<http://www.kamailioworld.com>
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