[Serusers] Please help with ser/nathelper

Enky asterisk at bgopentel.com
Tue Nov 29 04:12:26 CET 2005


Hi,
I am trying to run the SER as an outbound proxy. Unfortunately I have some problems. I have used the nathelper/rtpproxy with a customized ser.conf and the result is that the clients behind NAT are making outbound calls with no problems. The audio is two-way and all seems best, but when I try to react a client behind NAT I can not. It is registered in the SIP Proxy, but I can not dial it.
My scenario is: SER with MySQL authorization on the first PC and SER with nathelper/rtpproxy for outbound proxy on second PC.
Could someone give me some hint as I can not solve this problem. The Outbound Proxy SER version is:
version: ser 0.9.3 (i386/linux)
flags: STATS: Off, USE_IPV6, USE_TCP, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, FAST_LOCK-ADAPTIVE_WAIT
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144, MAX_LISTEN 16, MAX_URI_SIZE 1024, BUF_SIZE 65535
@(#) $Id: main.c,v 1.197 2004/12/03 19:09:31 andrei Exp $
main.c compiled on 20:51:59 Jun 28 2005 with gcc 3.3

The ser.cfg of the Outbound Proxy SER is:
#
# $Id: nathelper.cfg,v 1.1 2003/11/10 14:15:36 janakj Exp $
#
# simple quick-start config script including nathelper support

# This default script includes nathelper support. To make it work
# you will also have to install Maxim's RTP proxy. The proxy is enforced
# if one of the parties is behind a NAT.
#
# If you have an endpoing in the public internet which is known to
# support symmetric RTP (Cisco PSTN gateway or voicemail, for example),
# then you don't have to force RTP proxy. If you don't want to enforce
# RTP proxy for some destinations than simply use t_relay() instead of
# route(1)
#
# Sections marked with !! Nathelper contain modifications for nathelper
#
# NOTE !! This config is EXPERIMENTAL !
#
# ----------- global configuration parameters ------------------------

debug=3         # debug level (cmd line: -dddddddddd)
fork=yes
log_stderror=no # (cmd line: -E)

/* Uncomment these lines to enter debugging mode
fork=no
log_stderror=yes
*/

check_via=no # (cmd. line: -v)
dns=no           # (cmd. line: -r)
rev_dns=no      # (cmd. line: -R)
port=5082
children=4
fifo="/tmp/ser_fifo"

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

# Uncomment this if you want to use SQL database
#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"

# !! Nathelper
loadmodule "/usr/local/lib/ser/modules/nathelper.so"

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

# -- 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)

# -- 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")

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

# !! Nathelper
modparam("registrar", "nat_flag", 6)
modparam("nathelper", "natping_interval", 60) # Ping interval 60 s
modparam("nathelper", "ping_nated_only", 1)   # Ping only clients behind NAT

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

# main routing logic

route{

 # 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 ) {
  sl_send_reply("513", "Message too big");
  break;
 };

        # !! Nathelper
 # Special handling for NATed clients; first, NAT test is
 # executed: it looks for via!=received and RFC1918 addresses
 # in Contact (may fail if line-folding is used); also,
 # the received test should, if completed, should check all
 # vias for rpesence of received
 if (nat_uac_test("3")) {
  # Allow RR-ed requests, as these may indicate that
  # a NAT-enabled proxy takes care of it; unless it is
  # a REGISTER

  if (method == "REGISTER" || ! search("^Record-Route:")) {
      log("LOG: Someone trying to register from private IP, rewriting\n");

      # This will work only for user agents that support symmetric
      # communication. We tested quite many of them and majority is
      # smart enough to be symmetric. In some phones it takes a configuration
      # option. With Cisco 7960, it is called NAT_Enable=Yes, with kphone it is
      # called "symmetric media" and "symmetric signalling".

      fix_nated_contact(); # Rewrite contact with source IP of signalling
      if (method == "INVITE") {
          fix_nated_sdp("1"); # Add direction=active to SDP
      };
      force_rport(); # Add rport parameter to topmost Via
      setflag(6);    # Mark as NATed
  };
 };

 # we record-route all messages -- to make sure that
 # subsequent messages will go through our proxy; that's
 # particularly good if upstream and downstream entities
 # use different transport protocol
 if (!method=="REGISTER") record_route();

 # subsequent messages withing a dialog should take the
 # path determined by record-routing
 if (loose_route()) {
  # mark routing logic in request
  append_hf("P-hint: rr-enforced\r\n");
  route(1);
  break;
 };

 if (!uri==myself) {
  # mark routing logic in request
  append_hf("P-hint: outbound\r\n");
  route(1);
  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") {

   save("location");
   break;
  };

  lookup("aliases");
  if (!uri==myself) {
   append_hf("P-hint: outbound alias\r\n");
   route(1);
   break;
  };

  # native SIP destinations are handled using our USRLOC DB
  if (!lookup("location")) {
   sl_send_reply("404", "Not Found");
   break;
  };
 };
 append_hf("P-hint: usrloc applied\r\n"); 
 route(1);
}

route[1] 
{
 # !! Nathelper
 if (uri=~"[@:](192\.168\.|10\.|172\.(1[6-9]|2[0-9]|3[0-1])\.)" && !search("^Route:")){
     sl_send_reply("479", "We don't forward to private IP addresses");
     break;
        };

 # if client or server know to be behind a NAT, enable relay
 if (isflagset(6)) {
     force_rtp_proxy();
 };

 # NAT processing of replies; apply to all transactions (for example,
 # re-INVITEs from public to private UA are hard to identify as
 # NATed at the moment of request processing); look at replies
 t_on_reply("1");

 # send it out now; use stateful forwarding as it works reliably
 # even for UDP2TCP
 if (!t_relay()) {
  sl_reply_error();
 };
}

# !! Nathelper
onreply_route[1] {
    # NATed transaction ?
    if (isflagset(6) && status =~ "(183)|2[0-9][0-9]") {
        fix_nated_contact();
 if (!search("^Content-Length:\ 0")) {
  force_rtp_proxy();
 };
    # otherwise, is it a transaction behind a NAT and we did not
    # know at time of request processing ? (RFC1918 contacts)
    } else if (nat_uac_test("1")) {
        fix_nated_contact();
    };
}

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