Re: Kamailio as a Stateless Smart SIP Proxy

https://www.kamailio.org/docs/modules/5.0.x/modules/nathelper.html#nathelper.f.fix_nated_contact
? With combination of alias and other parameter, means you can store full
original contact header (encoded) in a Contact params as well.
Yes, it brakes RFC, but you can handle it manually

Le lun. 14 juil. 2025 à 14:36, Antonio via sr-users <
[email protected]> a écrit :

> BUT
> When Kamailio forwards REGISTER to Upstream(Asterisk), it will  contain
> the REAL IP of the UAC
>
> so later if someone will dial  UAC it will not path through  Kamailio
>
> On Sat, Jul 12, 2025 at 9:32 PM Alex Balashov via sr-users <
> [email protected]> wrote:
>
>> Hi,
>>
>> Yes, that's exactly what those functions enable.
>>
>> When you receive the REGISTER request, you use set_contact_alias() /
>> add_contact_alias() to add an `;alias` parameter to the Contact, which
>> reflects the client's external IP/port/transport. You then pass that
>> REGISTER request onto the registrar.
>>
>> When you get an incoming request from the registrar to the client, you
>> use handle_ruri_alias() to read the `;alias` parameter and load the
>> IP/port/transport values into the destination set ($du), while stripping
>> the `;alias` parameter off the RURI. You then t_relay() the request, which
>> will follow $du to the next hop read from the `;alias` parameter.
>>
>> -- Alex
>>
>> > On Jul 11, 2025, at 4:28 PM, Antonio <[email protected]> wrote:
>> >
>> > Thanks for the reply
>> >
>> > I want to use Kamailio as a proxy, but a smart one.
>> > It doesn't store anything, but:
>> > • Modifies REGISTER requests → adds the client's IP/port to Contact
>> > • So when the PBX sends an INVITE back, Kamailio reads this data from
>> the R-URI and forwards the call to the client
>> >
>> > Hope it makes sense.
>> >
>> >
>> > On Fri, Jul 11, 2025 at 10:14 PM Alex Balashov via sr-users <
>> [email protected]> wrote:
>> > Hi,
>> >
>> > The set_contact_alias() / handle_ruri_alias() functions from the
>> `nathelper` module[1] are quite ready-made for this use-case, though you
>> may need a more sophisticated approach if the upstream registrar does not
>> support Path[2][3].
>> >
>> > -- Alex
>> >
>> > [1] https://kamailio.org/docs/modules/6.0.x/modules/nathelper.html
>> >
>> > [2] https://datatracker.ietf.org/doc/html/rfc3327
>> >
>> > [3]
>> https://kamailio.org/docs/modules/6.0.x/modules/path.html#path.f.add_path
>> >
>> > > On Jul 11, 2025, at 6:19 AM, Antonio via sr-users <
>> [email protected]> wrote:
>> > >
>> > > Hi everyone,
>> > > Do we have a ready-to-use Kamailio role or configuration for:
>> > >
>> > > “Kamailio as a Stateless Smart SIP Proxy”,
>> > > Specifically one that uses Contact Header Encoding?
>> > >
>> > > That is — a proxy where Kamailio does not store registration state,
>> > > but encodes the client’s IP and port into the Contact header during
>> REGISTER,
>> > > and later decodes it from the INVITE to forward the call back to the
>> client.
>> > > Thanks in advance!
>> > > --
>> > >
>> > > Antony
>> > > [email protected]
>> > > __________________________________________________________
>> > > Kamailio - Users Mailing List - Non Commercial Discussions --
>> [email protected]
>> > > To unsubscribe send an email to [email protected]
>> > > Important: keep the mailing list in the recipients, do not reply only
>> to the sender!
>> >
>> > --
>> > Alex Balashov
>> > Principal Consultant
>> > Evariste Systems LLC
>> > Web: https://evaristesys.com, https://www.csrpswitch.com
>> > Tel: +1-706-510-6800
>> >
>> > __________________________________________________________
>> > Kamailio - Users Mailing List - Non Commercial Discussions --
>> [email protected]
>> > To unsubscribe send an email to [email protected]
>> > Important: keep the mailing list in the recipients, do not reply only
>> to the sender!
>> >
>> >
>> > --
>> >
>> > Antony
>> > [email protected]
>>
>> --
>> Alex Balashov
>> Principal Consultant
>> Evariste Systems LLC
>> Web: https://evaristesys.com, https://www.csrpswitch.com
>> Tel: +1-706-510-6800
>>
>> __________________________________________________________
>> Kamailio - Users Mailing List - Non Commercial Discussions --
>> [email protected]
>> To unsubscribe send an email to [email protected]
>> Important: keep the mailing list in the recipients, do not reply only to
>> the sender!
>>
>
>
> --
>
> *Antony*
> [email protected]
>
> __________________________________________________________
> Kamailio - Users Mailing List - Non Commercial Discussions --
> [email protected]
> To unsubscribe send an email to [email protected]
> Important: keep the mailing list in the recipients, do not reply only to
> the sender!
>


-- 
Best regards,
Ihor (Igor)

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