[Serusers] no audio problem if clients behind NATs
Klaus Darilion
klaus.mailinglists at pernau.at
Fri May 7 10:31:51 CEST 2004
You have to call force_rtpproxy -> this will rewrite the IP address and
port with the one of the rtpproxy.
klaus
Sun Yen-Rong (Dan) wrote:
> Hi Klaus,
> Firstly, thanks for your help. I used ethereal to capture the SIP
> messages, and found out that the SDP in the forwarded INIVITE and 200 OK
> message are not rewritten correctly. As a result, the client with a
> public IP address is sending RTP packets to the private IP address of
> the other client who is behind a NAT. One seruser suggested me to use
> fix_nated_sdp("3") instead of fix_nated_sdp("1"), however, it didn't
> solve my problem. Do I also need to add a parameter to other nathelper
> functions as well?
>
> Regards,
> Dan.
>
>
> -----Original Message-----
> From: Klaus Darilion [mailto:klaus.mailinglists at pernau.at]
> Sent: Thursday, May 06, 2004 9:45 PM
> To: Sun Yen-Rong (Dan)
> Cc: serusers at lists.iptel.org
> Subject: Re: [Serusers] no audio problem if clients behind NATs
>
> use a packet sniffer (ethereal or ngrep) and watch the SIP messages at
> the SIP proxy. Take a look at the sdp in the forwarded INVITE and 200 OK
>
> message and verify that the IP address and port in the SDP are rewritten
>
> correctly and points to the rtpproxy.
>
> regards,
> klaus
>
> Sun Yen-Rong (Dan) wrote:
>
>
>>Hi all,
>>
>>I am using ser 0.8.12 with nathelper and rtpproxy. When I tried to
>
> make
>
>>a call between two clients which are behind the same NAT, everything
>>work fine. However, when I try to make a call between clients which
>
> are
>
>>behind different NATs, niether client can hear each other's audio. my
>>configuration file is shown in the end of this message. Can someone
>
> help
>
>>me, please?
>>
>>Thanks,
>>
>>Dan.
>>
>>#
>># $Id: nathelper.cfg,v 1.1.2.1 2003/11/24 14:47:18 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)
>>
>>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 ----------------------------------
>>",#
>># $Id: nathelper.cfg,v 1.2 2003/04/15 20:35:29 jiri Exp $
>>#
>># example script showing use of nathelper module
>># (incomplete for sake of brevity)
>>#
>>
>># ----------- global configuration parameters ------------------------
>>
>># ------------------ module loading ----------------------------------
>>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"
>>
>># !! Nathelper
>>loadmodule "/usr/local/lib/ser/modules/nathelper.so"
>>
>># ----------------- 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)
>>
>># !! Nathelper
>>modparam("registrar", "nat_flag", 6)
>>modparam("nathelper", "natping_interval", 30) # Ping interval 30 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") {
>>
>># Uncomment this if you want to use digest authentication
>># if (!www_authorize("iptel.org", "subscriber")) {
>># www_challenge("iptel.org", "0");
>># break;
>># };
>>
>> 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();
>> 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();
>> };
>>}
>>
>>
>>_______________________________________________
>>Serusers mailing list
>>serusers at lists.iptel.org
>>http://lists.iptel.org/mailman/listinfo/serusers
>>
>>
>
>
>
>
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