Interesting! In my particular case, it's a Netgear ADSL router running a
version of uCLinux or something similar. The Netgear firmware is
apparently available for download (minus some proprietry WWW frontend
and related stuff) in order to comply to the GPLv2, but I haven't taken
the time to do this in order to check which Netfilter modules are being
used by the particluar 2.4.x kernel. In any case, I'm not particularly
good at C, so it wouldn't do me any good anyway. 

However, in my
experience the "statefulness" of a Linux Netfilter-based gateway should
be sufficient to be able to handle a situation like this transparently,
unless there is still something fundamental that I'm missing. 

  

Be that as it may, the simple question still remains: is it possible to
handle more than one UA behind a single NAT gateway with a single SER
setup on the outside of the NAT gateway (RFC 1918 address space inside,
normal routable IP outside)? Alternatively, would it be best to have an
inside SER that simply forwards all SIP traffic to the outside SER?

  

On Sun, 2005-12-04 at 11:05 +0100, Harry Behrens wrote:
  

could be an issue of the local gateway. most NAT devices explicitly 
block "hairpinning", which is happening in your case.


    -h

Jan Henkins wrote:

    

Hello Rafael,

This is an issue I'm having at the moment as well, where two UA's are
behind the same nat. SIP obviously works fine, I can ring one UA from
the other (one UA a Grandstream Budgetone 100 and the other the X-Lite
softphone from Counterpath). Audio doesn't work. Did you get this
working with forcing rtpproxy?

On Fri, 2005-12-02 at 09:44 -0500, Rafael R. GV wrote:
 

      

Hi
I need to let the UAs speak directly to each other without force
rtpproxy, Is there any solution for this issue?

rafael


---------- Forwarded message ----------
From: Rafael J. Risco G.V. <rafael.risco@gmail.com>
Date: Apr 22, 2005 2:17 PM
Subject: UA´s behind same NAT using na thelper/rtpproxy, No Audio...
To: serusers@lists.iptel.org

I am using avpops to enable SER to see if the UAs are located behind
the same address and now I need to let the UAs speak directly to each
other (without force rtpproxy), please someone see my configuration 
below and send some advice.

rafael

----.
              if (!lookup("location")) {
                      log(1,"unable to locate user \n");
                      # handle user which was not found 
                      route(4);
                      break;
              };

              ### Test if UAS are in the same NAT:
              # get the host part of the final uri (IP part)
              # and store it in AVP ID 13 

              avp_write("$ruri/domain", "i:13");
              if (avp_check("i:13","eq/$src_ip/i")) {
                      log(1, "source IP is the same as destination IP
\n"); 
                      route(3);
                      break;
              };
              avp_delete("i:13/g");
.
.
# -------------- Same NAT Call Routing (no force rtpproxy) ----

route[3]{
      log(1," route[3]: UAs are in the same nat, NO force_rtp_proxy
");

### Do something!!!!

      if(!t_relay()){
              sl_reply_error();
      };
}
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