Kamailio as a SBC - sr-users

16 Dec 2015

Hi everyone,

I'm trying to make kamailio works as a SBC in front of Asterisk. I have read the
tutorial http://kb.asipto.com/asterisk:realtime:kamailio-4.0.x-asterisk-11.3.0-astdb and
it is close to what I'm looking for but still a little different. I want don't
want kamailio to do auth and I want it to be a media gateway. The media and SIP path have
to look like that:

Phone 1 ----- kamailio -----Asterisk ---- Kamailio ---- Phone 2

First I have add an outboundproxy field in the Asterisk configuration to make all SIP
messages from Asterisk passe through Kamailio. Then I started a minimal conf for Kamailio
and it works at least for the SIP part. Call can be established perfectly. 

However the RTP proxy part is a mess. Kamailio changes the IP address in the sdp part only
for INVITE messages and not for the 200 OK responses, so there is only one side of the
media passing through Kamailio, the other side is sent directly to asterisk. But even for
the half part rtpproxy craches with a segfault and Kamailio doesn't transmit this
media.

I have been searching some helps on google but nothing so far :/ I hope that someone here
could help me.

-----------------------------------------------
#!KAMAILIO

####### Defined Values #########

#!define ASTERISK 192.168.51.43

####### Global Parameters #########

#!ifdef WITH_DEBUG
debug=4
log_stderror=no
#!else
debug=2
log_stderror=no
#!endif

memdbg=5
memlog=5

log_facility=LOG_LOCAL0

fork=yes
children=2

auto_aliases=no

# to avoid simple attacks, use unconventional port
port=5060

####### Modules Section ########

mpath="/usr/local/lib/kamailio/modules"

loadmodule "db_text.so"

loadmodule "mi_fifo.so"
loadmodule "kex.so"
loadmodule "sl.so"
loadmodule "rr.so"
loadmodule "pv.so"
loadmodule "maxfwd.so"
loadmodule "textops.so"
loadmodule "siputils.so"
loadmodule "xlog.so"
loadmodule "sanity.so"
loadmodule "ctl.so"
loadmodule "cfg_rpc.so"
loadmodule "mi_rpc.so"
loadmodule "path.so"
loadmodule "rtpproxy.so"

#!ifdef WITH_DEBUG
loadmodule "debugger.so"
#!endif

# ----------------- setting module-specific parameters ---------------

modparam("mi_fifo", "fifo_name", "/tmp/kamailio_fifo")

# add value to ;lr param to cope with most of the UAs
modparam("rr", "enable_full_lr", 1)
# do not append from tag to the RR (no need for this script)
modparam("rr", "append_fromtag", 0)

modparam("path", "use_received", 1)

modparam("rtpproxy", "rtpproxy_sock", "udp:127.0.0.1:7722")

#!ifdef WITH_DEBUG
# ----- debugger params -----
modparam("debugger", "cfgtrace", 1)
#!endif

####### Routing Logic ########

route {
    xlog("L-ALERT", "new message !!!!!!!!!!!!!!!");
    if (!sanity_check()) {
        exit;
    }

    if ( !mf_process_maxfwd_header("10") )
    {
        sl_send_reply("483","To Many Hops");
        xlog("L_NOTICE", "$si $rm $ru -- too many hops\n");
        exit;
    }

    if (af==INET)
    {
        force_rport();

        if (src_ip != ASTERISK)
        {
            $du = "sip:192.168.51.43:5060";
            add_path_received();
            route(RTPPROXY);
            record_route();
        }
        else
        {
            loose_route();
            route(RTPPROXY);
            record_route();
        }
    }

    forward();
}

route[RTPPROXY] {

        rtpproxy_manage("cwei");

}

onreply_route {

    if (af==INET)
    {
        rtpproxy_manage("cwei");
    }

    return(1);
}

---------------------------------------------

Guillaume