[SR-Users] Presence, RLS, and NAT Traversal

[Peter Dunkley]

Hi Juha,

My configuration is trying to achieve exactly what you suggest.

The Kamailio presence and RLS modules send NOTIFYs using the route-set
established by the SUBSCRIBE.  This means that if I call
add_contact_alias() and just pass the SUBSCRIBE to the module the NOTIFY
will use that contact address as a request URI but the NOTIFY will not go
back through the Kamailio route processing.  Because it doesn't go back
through the route processing handle_ruri_alias() is never called for it. 
The end result is that Kamailio attempts to route the NOTIFY to my private
IP and fails.

My forwarding (looping) the SUBSCRIBE back to myself once forces NOTIFY
requests from the presence and RLS modules to go through the Kamailio
routing logic.  This means that handle_ruri_alias() gets called and the
request URIs of the NOTIFY (correctly) contain my private IP but the
requests are (correctly) routed to my NAT devices public IP.

As I said, this works for the presence.winfo NOTIFY from presence and the
first presence NOTIFY sent directly from RLS.  The problem is that there
seems to be a problem with the parsing of this forwarded SUBSCRIBE because
rls_handle_subscribe() doesn't work.  The RLS module never sends any
SUBSCRIBEs for the contacts in my resource list.

Regards,

Peter


> peter,
>
> i don't have experience with k rls module, but in my environment if
> initial subscribe comes from behind nat, i just call add_contact_alias
> and add a nat param to r-r header for in-dialog requests.  notifys from
> rls server then contain ;alias param in request uri and the nat param in
> route header.  based on these sip proxy is able to get thee get notifys
> to the uas behind nat.
>
> -- juha
>
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-- 
Peter Dunkley
Technical Director
Crocodile RCS Ltd