Re: [Kamailio-Users] Kamailio and RTPProxy

Hello,

On 12/14/09 1:24 PM, Bruce McAlister wrote:

Hi All,

I am trying to setup kamailio 1.5.3-notls for use with rtpproxy 1.2.1. I have a partially working setup, however, when I have a softphone configured behind nat it appears that rtpproxy is using the internal ip (prior to nat) to setup the sdp ports.

I have rtpproxy configured in bridge mode as follows:

rtpproxy -f -F -l public_ip/internal_ip -s udp:*:11211

depending on flags, the public or internal IP is used to update the sdp. If you get it in the wrong order, then change the flags e and i in force_rtp_proxy() call.

It is ok to have the internal ip in the sdp going to the phone in internal network.

Cheers, Daniel

I have kamailio's nathelper module setup as follows:

modparam("nathelper", "rtpproxy_sock", "udp:internal_ip:11211")

I then use a softphone (x-lite) behind a nat firewall (ip = 192.168.11.2) to establish a call, and the log of rtpproxy is as follows:

INFO:handle_command: new session ZmRkNjRlNjM0NzExZjQ5MWUxYjllOTFhZWFmZGZkMjY., tag 8330585e;1 requested, type strong INFO:handle_command: new session on a port 52572 created, tag 8330585e;1 INFO:handle_command: pre-filling caller's address with 192.168.11.2:35498 INFO:handle_command: lookup on ports 52572/40380, session timer restarted INFO:handle_command: pre-filling callee's address with internal_ip:11250 INFO:handle_delete: forcefully deleting session 1 on ports 52572/40380 INFO:remove_session: RTP stats: 906 in from callee, 0 in from caller, 906 relayed, 0 dropped INFO:remove_session: RTCP stats: 3 in from callee, 0 in from caller, 3 relayed, 0 dropped INFO:remove_session: session on ports 52572/40380 is cleaned up

In the log above it looks like rtpproxy is using 192.168.11.2:35498 as the remote ip/port combination to contact for the sdp session of the x-lite softphone. I would have thought that it would use the IP address that initial request was received from to establish this connection (via the fix_nated_contact() function).

My route logic in kamailio is a slightly modified default configuration that is installed with kamailio :

route{

. . .

     # NAT detection
     route(4);

. . .

route(1); }

route[1]{ if (check_route_param("nat=yes")) { setbflag(6); } # if (isflagset(5) || isbflagset(6)) { route(5); # }

     /* example how to enable some additional event routes */
     if (is_method("INVITE")) {
             #t_on_branch("1");
             t_on_reply("1");
             t_on_failure("1");
     }

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

}

route[4]{ force_rport(); if (nat_uac_test("19")) { if (method=="REGISTER") { fix_nated_register(); } else { fix_nated_contact(); } setflag(5); } return; }

Would the "fix_nated_contact" function in the "nat detection" route not fix the contact before passing over the request to rtpproxy to establish the sdp session?

route[5] { if (is_method("BYE")) { unforce_rtp_proxy(); } else if (is_method("INVITE")){ # force_rtp_proxy(); if(src_ip==internal_ip_of_media_server) force_rtp_proxy("ocfaei"); else force_rtp_proxy("ocfaie"); } if (!has_totag()) add_rr_param(";nat=yes"); return; }

onreply_route[1] { xdbg("incoming reply\n");

  # if ((isflagset(5) || isbflagset(6))&&

status=~"(183)|(2[0-9][0-9])") { if (status=~"(183)|(2[0-9][0-9])") { # force_rtp_proxy(); if(src_ip == internal_ip_of_media_server) force_rtp_proxy("ocfaei"); else force_rtp_proxy("ocfaie"); } if (isbflagset(6)) { fix_nated_contact(); } }

failure_route[1] { if (is_method("INVITE") && (isbflagset(6) || isflagset(5))) { unforce_rtp_proxy(); }

     if (t_was_cancelled()) {
             exit;
     }

}

Any pointers would be greatly appreciated.

Thanks Bruce

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