[Serusers] RTP Proxy: can' t have RTP traversing NAT

frbilles@libertysurf.fr frbilles at libertysurf.fr
Mon Nov 8 18:11:33 CET 2004


Hi.

I've been trying to fix this issue by myself for about a month but definitely needs your help.

I use SER 0.8.14 from CVS sources  with RTPProxy V 1.19 and can't have RTP stream working through NAT (the phone rings -- SIP is OK).

SER and RTPProxy run on the same server.

RTPProxy is up and running, and I set 777 rights to the socket:

[root at servername rtpproxy]# ll /var/run/rtpproxy.sock
srwxrwxrwx   1 root  root   0 Nov  8 16:22 /var/run/rtpproxy.sock=

I use as a client X-Lite V2.0 on each side.

Please find below the log (call initiated from Internet to a callee on our LAN) and the excellent ser.cfg file I found in the Serusers Archives.

Thank you in advance for your help.

Francois.



=====================================================================================================================
LOG:
=====================================================================================================================
Maxfwd module- initializing
 0(28184) mod_init(): Database connection opened successfuly
textops - initializing
 0(0) INFO: udp_init: SO_RCVBUF is initially 65535
 0(0) INFO: udp_init: SO_RCVBUF is finally 131070
 1(28186) rtpp_test: RTP proxy found, support for it enabled
 5(28195) INFO: fifo process starting: 28195
 2(28187) rtpp_test: RTP proxy found, support for it enabled
 3(28188) rtpp_test: RTP proxy found, support for it enabled
 4(28194) rtpp_test: RTP proxy found, support for it enabled
 5(28195) rtpp_test: RTP proxy found, support for it enabled
 5(28195) SER: open_uac_fifo: fifo server up at /tmp/ser_fifo...
 8(28208) rtpp_test: RTP proxy found, support for it enabled
 6(28206) rtpp_test: RTP proxy found, support for it enabled
10(28213) rtpp_test: RTP proxy found, support for it enabled
 7(28207) rtpp_test: RTP proxy found, support for it enabled
11(28214) rtpp_test: RTP proxy found, support for it enabled
 9(28209) rtpp_test: RTP proxy found, support for it enabled
 0(28184) rtpp_test: RTP proxy found, support for it enabled
 4(28194) -------------------------------------------
 4(28194) entering main loop
 4(28194) src address different than via header->NAT detected
 4(28194) force_rport and fix_nated_contact and setflag(5)
 4(28194) INVITE message received
 4(28194) -------------------------------------------
 4(28194) entering route[1] - relaying SIP message
 4(28194) at least one of the participants is NATed->record_route
 4(28194)      -->setting up reply processing ->onreply_route[1] 4(28194)      INVITE request-->force_rtp_proxy, set NATED-INVITE flag(7) 4(28194) relaying message ...
 3(28188) -------------------------------------------
 3(28188) onreply_route[1] entered
 3(28188) status 100 received
 4(28194) -------------------------------------------
 4(28194) onreply_route[1] entered
 4(28194) status 180 received
 2(28187) -------------------------------------------
 2(28187) onreply_route[1] entered
 2(28187) status 2xx or 183 2(28187) marked(7) as NATED-INVITE -> force_rtp_proxy
 2(28187) ERROR: send_rtpp_command: can't read reply from a RTP proxy
 2(28187) -------------------------------------------
 2(28187) onreply_route[1] entered
 2(28187) status 2xx or 183 2(28187) marked(7) as NATED-INVITE -> force_rtp_proxy
 2(28187) ERROR: send_rtpp_command: can't connect to RTP proxy
 3(28188) -------------------------------------------
 3(28188) entering main loop
 3(28188) BYE message received
 3(28188) -------------------------------------------








========================================================================================================================
SER.CFG
========================================================================================================================

#
# $Id: ser.cfg,v 1.21 2003/06/04 13:47:36 jiri Exp $
#
# simple quick-start config script
#

# ----------- global configuration parameters ------------------------

debug=3         # debug level (cmd line: -dddddddddd)
fork=yes
log_stderror=yes # (cmd line: -E)


listen=<ip address in the DMZ>
#listen=127.0.0.1

# hostname matching an alias will satisfy the condition uri==myself".
alias=servername.mycompany.com
alias=mycompany.com localhost


# Uncomment these lines to enter debugging mode
#debug=7
#fork=no
#log_stderror=yes



check_via=no    # (cmd. line: -v)
dns=no           # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
port=5060
children=4
fifo="/tmp/ser_fifo"

# ------------------ module loading ----------------------------------

loadmodule "/usr/local/lib/ser/modules/mysql.so"
loadmodule "/usr/local/lib/ser/modules/sl.so"
loadmodule "/usr/local/lib/ser/modules/tm.so"
loadmodule "/usr/local/lib/ser/modules/rr.so"
loadmodule "/usr/local/lib/ser/modules/maxfwd.so"
loadmodule "/usr/local/lib/ser/modules/usrloc.so"
loadmodule "/usr/local/lib/ser/modules/registrar.so"
loadmodule "/usr/local/lib/ser/modules/textops.so"

# Uncomment this if you want digest authentication
# mysql.so must be loaded !
loadmodule "/usr/local/lib/ser/modules/auth.so"
loadmodule "/usr/local/lib/ser/modules/auth_db.so"

# load the voicemail module
#loadmodule "/usr/local/lib/ser/modules/vm.so"

# load the enum module
loadmodule "/usr/local/lib/ser/modules/enum.so"

# load the group module, to verify if a user forwards to voicemail
loadmodule "/usr/local/lib/ser/modules/group.so"

# load the nathelper module
loadmodule "/usr/local/lib/ser/modules/nathelper.so"

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

# -- registrar parameter
# special NAT flag indicates that a registered client is behind NAT
modparam("registrar", "nat_flag", 6)

# -- usrloc params --

#modparam("usrloc", "db_mode",   0)

# Uncomment this if you want to use SQL database
# for persistent storage and comment the previous line
modparam("usrloc", "db_mode", 2)
#modparam("usrloc", "db_url", "mysql://login:password@localhost/ser")
modparam("usrloc|auth_db|acc|group|msilo|uri","db_url","mysql://login:password@localhost/ser")

# -- auth params --
# Uncomment if you are using auth module
#
modparam("auth_db", "calculate_ha1", yes)
#
# If you set "calculate_ha1" parameter to yes (which true in this config),
# uncomment also the following parameter)
#
modparam("auth_db", "password_column", "password")
#modparam("auth_db", "db_url", "mysql://login:password@localhost/ser")

# -- rr params --
# add value to ;lr param to make some broken UAs happy
modparam("rr", "enable_full_lr", 1)

# -- voicemail params --
#modparam("voicemail", "db_url","mysql://login:password@localhost/ser")

# -- voicemail params --
#modparam("group", "db_url","mysql://login:password@localhost/ser")

# -- nathelper params --
modparam("nathelper", "natping_interval", 60)
modparam("nathelper", "ping_nated_only", 1)

modparam("tm", "fr_inv_timer", 30 )
#modparam("tm", "fr_inv_timer", 8 )

#Explicitly set the socket used by rtpproxy
#modparam("nathelpler", "rtpproxy_sock", "/var/run/rtpproxy.sock")


# -------------------------  request routing logic -------------------

# main routing logic

route{
        log(1, "-------------------------------------------\n");
        log(1, "entering main loop\n");

        if (nat_uac_test("2")) {
                log(1, "src address different than via header->NAT detected\n");
                log(1, "force_rport and fix_nated_contact and setflag(5)\n");
                #try NAT traversal, works only if the client is symmetrical
                force_rport();
                fix_nated_contact();
                append_hf("P-hint: fixed NAT contact for request\r\n");
                # flag 5 indicates that incoming request is from NATed client
                setflag(5);
        };

        if (method=="REGISTER")
                log(1, "REGISTER message received\n");

        if (method=="INVITE")
                log(1, "INVITE message received\n");

        if (method=="ACK")
                log(1, "ACK message received\n");

        if (method=="BYE")
                log(1, "BYE message received\n");

        if (method=="CANCEL")
                log(1, "CANCEL message received\n");

        if (method=="SUBSCRIBE")
                log(1, "SUBSCRIBE message received\n");

        if (method=="NOTIFY")
                log(1, "NOTIFY message received\n");

        if (method=="OPTIONS")
                log(1, "OPTIONS message received\n");

        if (method=="INFO")
                log(1, "INFO message received\n");

        if (method=="MESSAGE")
                log(1, "MESSAGE message received\n");

        if (method=="REFER")
                log(1, "REFER message received\n");

        # initial sanity checks -- messages with
        # max_forwards==0, or excessively long requests
        if (!mf_process_maxfwd_header("10")) {
                sl_send_reply("483","Too Many Hops");
                break;
        };

        if (msg:len > max_len) {
        #if (len_gt( max_len )) {
                sl_send_reply("513", "Message too big");
                break;
        };

        # loose-route processing
        if (loose_route()) {
                log(1, "loose_route processing\n");
                t_relay();
                break;
        };

        # create transaction state; abort if error occured
#       if ( !t_newtran()) {
#               sl_reply_error();
#               break;
#       };

#new
                   # now check if it's about PSTN destinations through our gateway;
                    # note that 8.... is exempted for numerical non-gw destinations
                    if (uri=~"^sip:0[0-9]*@.*") {
                        route(3);
                        break;
                    };

#

        # if the request is for other domain use UsrLoc
        # (in case, it does not work, use the following command
        # with proper names and addresses in it)
        if (uri==myself) {

                if (method=="REGISTER") {
                        log(1, "analyzing REGISTER request\n");
# Uncomment this if you want to use digest authentication
                       if (!www_authorize("servername.mycompany.com", "subscriber")) {
                               www_challenge("servername.mycompany.com", "0");
                               break;
                       };

                        if (isflagset(5)) {
                                #register from nated client, save nat_flag=6
                                #in location table
                                setflag(6);
                        };
                        if (!save("location")) {
                                log(1, "save location error\n");
                                sl_reply_error();
                        };
                        break;
                };

                lookup("aliases");


                #mark transaction for voicemail
                if (is_user_in("Request-URI", "voicemail\n")) {
                        log(1, "requested user is in voicemail group");
                        setflag(4);
                };
                # native SIP destinations are handled using our USRLOC DB
                if (!lookup("location")) {
                        # handle user which was not found
                        log(1, "requested user not found\n");
                        route(4);
                        break;
                };
        };

        #add failure route which should be performed if response code >=300
        if  (method=="INVITE" && isflagset(4)) {
                log(1, "invite for voicemail user->initiate failureroute[1]\n");
                t_on_failure("1");
        };

        # forward to current uri now; use stateful forwarding; that
        # works reliably even if we forward from TCP to UDP

        route(1);
}

route[1]{
        log(1, "-------------------------------------------\n");
        log(1, "entering route[1] - relaying SIP message\n");
        if ((isflagset(5)) || (isflagset(6))) {
                log(1, "at least one of the participants is NATed->record_route\n");
                record_route();
                log(1, "     -->setting up reply processing ->onreply_route[1]");
                t_on_reply("1");
                if (method=="INVITE") {
                        log(1, "     INVITE request-->force_rtp_proxy, set NATED-INVITE flag(7)");
                        force_rtp_proxy();
                        append_hf("P-hint: request forced to rtp proxy\r\n");
                        setflag(7);
                };
        };

        log(1, "relaying message ...\n");
        if (!t_relay()) {
                log(1, "t_relay error occured\n");
                sl_reply_error();
        };

}

# all incoming replies for t_onrepli-ed transactions enter here
onreply_route[1] {
        log(1, "-------------------------------------------\n");
        log(1, "onreply_route[1] entered\n");
        if (isflagset(6)) {
                log(1, "transaction was sent to a NATED client -> fix nated contact\n");
                fix_nated_contact();
                append_hf("P-hint: fixed NAT contact for response\r\n");
        }

        if ( (status=~"100") ) {
                log(1, "status 100 received\n");
        };

        if ( (status=~"180") ) {
                log(1, "status 180 received\n");
        };

        if ( (status=~"202") ) {
                log(1, "status 202 received\n");
        };

        if ( (status=~"200" || status=~"183") ) {
                log(1, "status 2xx or 183");
                if ( isflagset(7) ) {
                        log(1, "marked(7) as NATED-INVITE -> force_rtp_proxy \n");
                        force_rtp_proxy();
                        append_hf("P-hint: response forced to rtp proxy\r\n");
                };
        };
}

#new
# logic for calls to the PSTN
route[3] {
        # turn accounting on
        setflag(1);

        /* require all who call PSTN to be members of the "int" group;
           apply ACLs only to INVITEs -- we don't need to protect other requests, as they
           don't imply charges; also it could cause troubles when a call comes in via PSTN
           and goes to a party that can't authenticate (voicemail, other domain) -- BYEs would
           fail then; exempt Cisco gateway from authentication by IP address -- it does not
           support digest
        */
        if (method=="INVITE" && (!src_ip==WhateverIP)) {
                if (!proxy_authorize(   "servername.mycompany.com" /* realm */,
                                                "subscriber" /* table name */))  {
                        proxy_challenge( "servername.mycompany.com" /* realm */, "0" /* no qop */ );
                        break;
                };
                # let's check from=id ... avoids accounting confusion

                if(!is_user_in("credentials", "int")) {
                        sl_send_reply("403", "NO PSTN Privileges...");
                        break;
                };
                consume_credentials();

        }; # INVITE to authorized PSTN

        # if you have passed through all the checks, let your call go to GW!
force_rtp_proxy();
record_route();
t_on_reply("1");
        # snom conditioner
        if (method=="INVITE" && search("User-Agent: snom")) {
                replace("100rel, ", "");
        };

        append_hf("P-hint: GATEWAY\r\n");
        # use UDP to guarantee well-known sender port (TCP ephemeral)
        t_relay_to_udp("212.17.35.184","5060");
}



route[4]{
        log(1, "-------------------------------------------\n");
        log(1, "entering route[4] = requested user not online\n");
        # non-Voip -- just send "off-line"
        if (!(method == "INVITE" || method == "ACK" || method == "CANCEL" || method == "REFER" || method == "BYE")) {
                log(1, "no invite,ack,cancel,refer->return 404\n");
                sl_send_reply("404", "Not Found");
                break;
        };

        # not voicemail subscriber and no echo/conference call
        if ( isflagset(4)) {
                log(1, "flag(4) active\n");
        };
        if (uri =~ "conference") {
                log(1, "conference call\n");
        };
        if (uri =~ "echo") {
                log(1, "echo call\n");
        };
        if ( !( isflagset(4) || (uri =~ "conference") || (uri =~ "echo") ) ) {
                log(1, "no voicemail subscriber->return 404");
                sl_send_reply("404", "Not Found and no voicemail turned on");
                break;
        };

        if ( isflagset(5) ) {
                log(1, "caller is NATed->record_route\n");
                record_route();
                log(1, "     -->setting up reply processing ->onreply_route[1]");
                t_on_reply("1");
                if (method=="INVITE") {
                        log(1, "     INVITE request-->force_rtp_proxy");
                        force_rtp_proxy();
                };
        };

        # forward to voicemail now
²        rewritehostport("WhateverIP:5060");
        log(1, "forward to voicemail\n");
        t_relay_to_udp("WhateverIP", "5060");

}



failure_route[1] {
  /* XX: note: unsafe if preloaded routes without username used */
        log(1, "-------------------------------------------\n");
        log(1, "failureroute[1] entered\");
        revert_uri();
        rewritehostport("WhateverIP:5060");
       append_branch();
        t_relay_to_udp("WhateverIP", "5060");

}

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