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

Daniel-Constantin Mierla miconda at gmail.com
Wed Jan 25 17:14:30 CET 2017


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


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>;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>;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>
> *Sent:* 25 January 2017 15:37
> *To:* Kamailio (SER) - Users Mailing List; 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>;tag=carrier.peering.telecom.im+4+c538fe37+7570d4e5
>
>
>
>
>
> ------------------------------------------------------------------------
> *From:* sr-users <sr-users-bounces at lists.sip-router.org> on behalf of
> Daniel-Constantin Mierla <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
>> *From: "+44792498881474"
>> <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>
>> Route:
>> <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
>> *From: "+44792498881474"
>> <sip:+441444680332 at es132y$}-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>
>> 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
>>
>>
>>
>> _______________________________________________
>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>> sr-users at lists.sip-router.org
>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>
> -- 
> Daniel-Constantin Mierla
> www.twitter.com/miconda -- www.linkedin.com/in/miconda
> Kamailio Advanced Training - Mar 6-8 (Europe) and Mar 20-22 (USA) - www.asipto.com
> Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com

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

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