[Serusers] NAT Solution

Kapil Dhawan sersavvy at hotmail.com
Sat Apr 24 12:44:02 CEST 2004


Hi i checked it
and implemented rtpproxy also....

now what i am doing is.....if i take sample conf for rtpproxy it works but 
if i put it in my ser.cfg
it doens't. ring goes for device behind NAT but can't hear.

i am pasting my ser.cg for your reference...


i have written one call module also and its function is to work on call 
allow function, call deny, forward etc and it is working without including 
NAT moduel....but if i include NAT...public ip's can still talk but private 
can't only ring goes for them

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 ----------------------------------

# 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"

#added by kapil
loadmodule "/usr/local/lib/ser/modules/call.so"
loadmodule "/usr/local/lib/ser/modules/vm.so"
# !! Nathelper
loadmodule "/usr/local/lib/ser/modules/nathelper.so"
#added by kapil
# ----------------- 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", 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();
	# loose-route processing
	if (loose_route()) {
		# mark routing logic in request
		append_hf("P-hint: rr-enforced\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("", "subscriber")) {
			www_challenge("", "0");
			break;
		};

		save("location");
		break;
	};

	if (method=="INVITE" || method=="ACK" || method=="BYE" || method=="CANCEL") 
{

		if(call_feature()){

			if(uri=~"sip:7@")
			{
				if(!call_redial())
				{
					sl_send_reply("404", "Not Found");
					break;
				};
			}
			else if(uri=~"sip:00*")
			{
			    if(call_pstn())
			    {
			      break;
			    };
			}
			else
			{
				if(!call_speeddial())
				{
					sl_send_reply("404", "Not Found");
					break;
				};

			};

		}
		else
		{
		if(!call_sip()){
                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

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

	if(call_flag("1"))
	{
	if (!lookup("location")) {
	       sl_send_reply("404", "Not Found");
	       break;
	};

	if (!t_relay()) {
		sl_reply_error();
	};
	break;
	};

	if(call_flag("2"))
	{
	break;
	};

	if(call_flag("3"))
	{
                  if (!t_newtran()) {
                    log("could not create new transaction\n");
                    sl_send_reply("500","could not create new transaction");
                    break;
                  };
                  t_reply("100","Trying -- just wait a minute !");
                  if(!vm("/tmp/am_fifo","voicemail")){
                    log("could not contact the answer machine\n");
                    t_reply("500","could not contact the answer machine");
                  };
		  break;
	};
}

# !! 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();
    };
}



>From: Atle Samuelsen <clona at camaro.no>
>To: Kapil Dhawan <sersavvy at hotmail.com>
>CC: serusers at lists.iptel.org
>Subject: Re: [Serusers] NAT Solution
>Date: Sat, 24 Apr 2004 12:18:55 +0200
>
>
>Hi!
>
>www.google.com  and search for "ser +nat :host mail.iptel.org"
>
>otherstuff, rtpproxy, mediaproxy etc.
>
>btw. Check the list for common queristions :-)
>
>
>-Atle
>
>
>* Kapil Dhawan <sersavvy at hotmail.com> [040424 07:07]:
> > Hi
> >
> > Could you pls suggest me some solution for implementing NAT. I have 
>almost
> > all the devices behind NAT. Pls suggest me that where can i get the
> > documentation for that too...
> >
> > Regards
> >
> > _________________________________________________________________
> > Deals can't get any better. Products at Lowest Prices.
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> >

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