[SR-Users] Topoh hiding prefixes

[Efelin Novak]

I have to apologize.

The Topoh module hides the whole contact not just a domain part. So
The problem is fixed.

However don't you have any experinece with clients that have problems
with seq. requests being sent to some "random" string expect of the
propagated contact?

UA  ---invite --->   kamailio(topoh)  ---invite --->  UA
UA  <---200ok---   kamailio(topoh)  <---200ok---  UA (sent contact=
100 at 192.168.1.101)
UA  ---ACK--->     kamailio(topoh)  ---ACK--->   UA (received ru=
sip:<topoh_ip>;line=sr--random_string SIP/2.0 )

Also fix_nated_contact() destroys the contact so I suppose there
should be no problem whit this.

Thank anyway

Efelin
2012/2/17 Efelin Novak <efelin.novak at gmail.com>:
> Hi Alex,
>
> thanks for the answer.
>
> My customer is on the SIP side. So my customer sees a prefix of my
> PSTN gateway in the contact header. Sequential requests are being sent
> to <prefix><number>@<gateway_ip>. However I think when I remove the
> prefix from the contact, the gateway would have no problem in
> responding to this seq. request (Isn't the call defined by to_tag,
> from_tag, call_id?).
>
> So I want to hide the contact prefix from the UA.
>
> Efelin
>
> 2012/2/17 Alex Balashov <abalashov at evaristesys.com>:
>> Efelin,
>>
>> There is probably some confusion here.  The 200 OK message is from your gateway (in your call flow), and it can put whatever it wants in the Contact URI; you have no control over that on the Kamailio side.  You might be able to influence it with configuration settings on the GW side, but most likely not.
>>
>> However, much more importantly: the contact URI in the replies from the gateway only serves to target your UA's sequential requests.  It has nothing to do with the other side of your GW.  If it's a SIP -> TDM or analog GW, then SIP details are totally irrelevant.  If it's a SIP-to-SIP media gateway, it's a back-to-back user agent, meaning it generates a whole new logical call leg on the other side and bridges it to the incoming one from the UA.  The parameters in that new leg are completely independent of any attributes of the old one.
>>
>> Regardless, the contact URI is something sent back to the UA to tell it how to communicate with the GW.  In the overall scheme of your call flow,  no matter the media, it is a "purely internal" attribute.
>>
>> --
>> This message was painstakingly thumbed out on my mobile, so apologies for brevity and errors.
>>
>> Alex Balashov - Principal
>> Evariste Systems LLC
>> 260 Peachtree Street NW
>> Suite 2200
>> Atlanta, GA 30303
>> Tel: +1-678-954-0670
>> Fax: +1-404-961-1892
>> Web: http://www.evaristesys.com/, http://www.alexbalashov.com
>>
>> On Feb 17, 2012, at 9:20 AM, Efelin Novak <efelin.novak at gmail.com> wrote:
>>
>>> Hi folks,
>>>
>>> I have a topology like this:
>>>
>>> UA -> kamailio -> PSTN GW.
>>>
>>> When I'm placing calls to a PSTN I have to append prefixes so the PSTN
>>> GW knows how to route the call. So the request-uri is
>>> <prefix><number>@<gateway_ip> e.g. 999123456 at 192.168.1.1. When the UA
>>> calls to the GW a "200 OK" message contains a contact header with
>>> 999123456 at 192.168.1.1. This is a problem because I don't want my
>>> customers to see gateway prefixes.
>>>
>>> The Topoh module only hides IP addresses or the  domain part. Is there
>>> any way to remove prefixes. This document
>>> (http://www.kamailio.org/events/2011-Cluecon/DCM-kamailio-security.pdf)
>>> stated "encoding IP and prefixes can be set via parameters". Can I
>>> remove prefixes from the contact in any other way than some contact
>>> header substitutions?
>>>
>>> Thanks
>>>
>>> Efelin
>>>
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