[asterisk-users] SER+Asterisk integration

[Arnd Vehling]

have a look at the nathelper examples in SER distribution. This is from
an rather old installation of mine.
--
  # !! 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:")) {
                     xlog("L_ERR", "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 i
s
                     # smart enough to be symmetric. In some phones it takes a co
nfiguration
                     # 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 sig
nalling
                     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
                 };
         };

..

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

--