Rtpproxy not work in 2 kamailio + rtpproxy setup - sr-users

27 Feb 2020

Dear Community,

I have a problem with rtpproxy not changing the SDP IP in connection
information in following scenario:

SIP1 -> kamailio1 + rtpproxy1 -> kamailio2 + rtpproxy2 -> SIP2

The first kamailio put SDP IP correctly (from rtpproxy) then the second
kamailio does not change SDP connection information.

I think its related to SDP body which has:

a=nortpproxy:yes

line added by kamailio1.

So i tried to remove the a=nortpproxy:yes line from SDP before calling
rtpproxy_manage.
But it looks like no difference in working - i think the SDP sent to
rtpproxy is still having the line even when i removed it.

The issue is not happening when i remove kamailio1 + rtpproxy1. In that
case my IP is put correctly in SDP in INVITE and in 200 OK.

In case of two kamailio with rtpproxy (kamailio1 and kamailio2) in
signalling path i am getting:

rtpproxy [rtpproxy.c:2586]: force_rtp_proxy(): incorrect port 0 in reply
from rtp proxy

for replies (SIP2 IP address in 200OK SDP is present instead of kamailio2
IP address).
For request INVITE i am not getting the error but the IP in SDP doesn't
change.

kamailio2 config is now like below (but the attempt to remove
a=nortpproxy:yes, did not work for me)

# RTPProxy control and signaling updates for NAT traversal
route[NATMANAGE] {
#!ifdef WITH_NAT
        if (is_request()) {
                if(has_totag()) {
                        if(check_route_param("nat=yes")) {
                                setbflag(FLB_NATB);
                        }
                }
        }
#       if (!(isflagset(FLT_NATS) || isbflagset(FLB_NATB))) return; --
commented this out because sometimes rtpproxy was not used and i wanted to
use it always

# added below code to remove a=nortpproxy:yes from SDP before
rtpproxy_manage but its still not working

        if( has_body("application/sdp") && (1 ==
sdp_get_line_startswith("$avp(nortpproxy)", "a=nortpproxy" )) ){
                sdp_remove_line_by_prefix("a=nortpproxy:yes");
                xlog("removed nortpproxy:yes from SDP");
        }

        if(nat_uac_test("8")) {
                xlog("rtpproxy CO");
                rtpproxy_manage("co","MY_PUBLIC_IP_HERE");
        } else {
                xlog("rtpproxy COR");
                rtpproxy_manage("cor"," MY_PUBLIC_IP_HERE ");
        }

        if (is_request()) {
                if (!has_totag()) {
                        if(t_is_branch_route()) {
                                add_rr_param(";nat=yes");
                        }
                }
        }
        if (is_reply()) {
                if(isbflagset(FLB_NATB)) {
                        if(is_first_hop())
                                set_contact_alias();
                }
        }

        if(isbflagset(FLB_NATB)) {
                # no connect message in a dialog involving NAT traversal
                if (is_request()) {
                        if(has_totag()) {
                                set_forward_no_connect();
                        }
                }
        }
#!endif
        return;
}

Best regards,
Tom

PS. thanks for any hints to resolve the issue.