[Serusers] SER as an ALG.

I have been trying to configure SER w/MediaProxy module/server to be a drop in NAT solution in front of asterisk. With the twist that I want to have asterisk continue acting as a registrar rather than SER. Outbound calls from natted clients works perfectly currently. The problem I'm having is with SER passing the REGISTERS through to asterisk. SER/MP isn't rewriting the address in the packets to go back through SER, but instead sets it to be the NAT'd IP of the client. So, when asterisk receives a call, and tries to send it to the external nat'd IP of the client, there is no open session from asterisk, so the firewall denies the request. What I need to happen, is for SER/MP to rewrite the packet with it's own IP, so that asterisk sends it back to SER, and SER forwards it back down to the client, from a source IP which has an open firewall session. Any help would be greatly appreciated, hopefully it's just a matter of me having an extraneous function call somewhere, or being ignorant of the right function to use. Or, in ascii diagram form: NAT_IP client --- EXTERNAL_FW_IP ----- SER_IP ----- ASTERISK SER is giving asterisk the EXTERNAL_FW_IP for Registers, and I want it to give Asterisk the SER IP. Something that would make SER rewrite *all* register packets to it's own IP would even work, since clients that don't need NAT won't be sent to SER in the first place. My ser.cfg and mediaproxy.ini follow. Lemme know if you need any more info from me. And extra thanks to anyone who has taken the time reading this, I truly appreciate it. kyle. # ### ser.cfg ### # # ----------- 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=5070 #children=4 fifo="/tmp/ser_fifo" #fifo_db_url="mysql://ser:ser/ser" # ------------------ 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/dbtext.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" loadmodule "/usr/local/lib/ser/modules/domain.so" # !!! Media Proxy loadmodule "/usr/local/lib/ser/modules/mediaproxy.so" #modparam("mediaproxy", "mediaproxy_socket", "/var/run/proxydispatcher.sock") modparam("mediaproxy", "mediaproxy_socket", "/var/run/mediaproxy.sock") #modparam("mediaproxy", "sip_asymmetrics", "/usr/local/etc/ser/sip-asymmetric-clients") #modparam("mediaproxy", "rtp_asymmetrics", "/usr/local/etc/ser/rtp-asymmetric-clients") modparam("mediaproxy", "natping_interval", 20) # ----------------- setting module-specific parameters --------------- # -- usrloc params -- modparam("usrloc", "db_mode", 0) # -- rr params -- # add value to ;lr param to make some broken UAs happy modparam("rr", "enable_full_lr", 1) # ------------------------- 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; }; if (client_nat_test("3")) { # Allow RR-ed requests, as these may indicate that # a NAT-enabled proxy takes care of it; unless it is # a REGISTER fix_contact(); # Rewrite contact with source IP of signalling force_rport(); # Add rport parameter to topmost Via setflag(6); # Mark as NATed # use_media_proxy(); }; # 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(); 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; }; route(1); } route[1] { 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)) { use_media_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(); }; } onreply_route[1] { # NATed transaction ? if (isflagset(6) && status =~ "(183)|2[0-9][0-9]") { use_media_proxy(); # otherwise, is it a transaction behind a NAT and we did not # know at time of request processing ? (RFC1918 contacts) } else if (client_nat_test("1")) { fix_contact(); use_media_proxy(); }; } ; ; Configuration file for MediaProxy ; [Dispatcher] start = yes socket = /var/run/proxydispatcher.sock ;group = ser defaultProxy = /var/run/mediaproxy.sock [MediaProxy] start = yes socket = /var/run/mediaproxy.sock ;group = ser ;listen = None ;allow = None ;proxyIP = 127.0.0.1 portRange = 35000:65000 ;TOS = 0xb8 ;idleTimeout = 60 ;holdTimeout = 3600 ;forceClose = 0 accounting = off [Accounting] user = dbuser password = dbpass host = dbhost database = radius table = radacct