manpage.xml

RTP Proxy,用于Voip网络数据的代理传递

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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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  <!ENTITY dhfirstname "<firstname>Maxim</firstname>">
  <!ENTITY dhsurname   "<surname>Sobolev</surname>">
  <!-- Please adjust the date whenever revising the manpage. -->
  <!ENTITY dhdate      "<date>Jun 16, 2008</date>">
  <!-- SECTION should be 1-8, maybe w/ subsection other parameters are
       allowed: see man(7), man(1). -->
  <!ENTITY dhsection   "<manvolnum>8</manvolnum>">
  <!ENTITY dhemail     "<email>[e-mail]</email>">
  <!ENTITY dhusername  "janakj">
  <!ENTITY dhucpackage "<refentrytitle>rtpproxy</refentrytitle>">
  <!ENTITY dhpackage   "rtpproxy">

  <!ENTITY debian      "<productname>Debian</productname>">
  <!ENTITY gnu         "<acronym>GNU</acronym>">
  <!ENTITY gpl         "&gnu; <acronym>GPL</acronym>">
]>

<refentry>
    <refentryinfo>
	<address>
	    &dhemail;
	</address>
	<author>
	    &dhfirstname;
	    &dhsurname;
	</author>
	<copyright>
	    <year>2006</year>
	    <holder>&dhusername;</holder>
	</copyright>
	&dhdate;
    </refentryinfo>
    <refmeta>
	&dhucpackage;
	
	&dhsection;
    </refmeta>
    <refnamediv>
	<refname>&dhpackage;</refname>
	<refpurpose>RTP (Real-time Transport Protocol) Proxy Server</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
	<cmdsynopsis>
	    <command>&dhpackage;</command>
	    
	    <arg choice="opt"><option>-?</option></arg>
	    <arg choice="opt"><option>-2</option></arg>
	    <arg choice="opt"><option>-f</option></arg>
	    <arg choice="opt"><option>-v</option></arg>
	    <arg choice="opt"><option>-R</option></arg>
	    <arg choice="opt"><option>-l</option> <replaceable>addr1<optional>/addr2</optional></replaceable></arg>
	    <arg choice="opt"><option>-6</option> <replaceable>addr1<optional>/addr2</optional></replaceable></arg>
	    <arg choice="opt"><option>-s</option> <replaceable>ctrl_socket</replaceable></arg>
	    <arg choice="opt"><option>-t</option> <replaceable>tos</replaceable></arg>
	    <arg choice="opt"><option>-p</option> <replaceable>pidfile</replaceable></arg>
	    <arg choice="opt"><option>-T</option> <replaceable>max_ttl</replaceable></arg>
	    <arg choice="opt">
		<option>-r</option> <replaceable>rdir</replaceable>
		<arg choice="opt"><option>-S</option> <replaceable>sdir</replaceable></arg>
	    </arg>
	    <arg choice="opt"><option>-m</option> <replaceable>min_port</replaceable></arg>
	    <arg choice="opt"><option>-M</option> <replaceable>max_port</replaceable></arg>
	    <arg choice="opt"><option>-u</option> <replaceable>uname<optional>:gname</optional></replaceable></arg>
	    <arg choice="opt"><option>-F</option></arg>
	</cmdsynopsis>
    </refsynopsisdiv>
    <refsect1>
	<title>DESCRIPTION</title>
	<para>
	    <command>&dhpackage;</command> is a symmetric RTP proxy designed to
	    be used in conjunction with the SIP Express Router (SER) or any
	    other SIP proxy or SIP B2BUA capable of rewriting SDP bodies in SIP messages
	    that it processes.
	</para>
	<para>
	    The main purpose of rtpproxy is to make the communication between
	    SIP user agents behind NAT(s) (Network Address Translator)
	    possible. Several cases exists when direct end-to-end communication
	    is not possible and RTP streams have to be relayed through another
	    host. Rtpproxy can be used to setup such a relaying host.
	</para>
	<para>
	    When two listen interfaces have been specified using the command
	    line parameters described below then rtpproxy will enter so called
	    bridging mode. In briding mode rtpproxy forwards RTP packets
	    received on one interface to the other interface and vice
	    versa. This mode can be used to forward RTP packets between
	    networks without direct network level connectivy (provided that the
	    host running rtpproxy has one interface in both of them). One
	    particular application of bridging mode is IPv4/IPv6 traversal of
	    RTP packets.
	</para>
	<para>
	    When instructured by SER rtpproxy can also record the entire RTP
	    session in a file on a local harddisk or play a pre-recorded file
	    to the user agent (so called Music-on-Hold).
	</para>
    </refsect1>
    <refsect1>
	<title>OPTIONS</title>
	<variablelist>
	    <varlistentry>
		<term><option>-?</option></term>
		<listitem>
		    <para>Show summary of options.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-2</option></term>
		<listitem>
		    <para>
			Send every RTP packet twice in sessions that use
			low-bitrate codecs. Only packets that are smaller than
			128 bytes will be sent twice. This option can improve
			audio quality on lossy links.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-f</option></term>
		<listitem>
		    <para>
			Rtpproxy will stay in foreground mode if this option is
			set.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-v</option></term>
		<listitem>
		    <para>Show version of program.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-l</option> <replaceable>addr1<optional>/addr2</optional></replaceable></term>
		<listitem>
		    <para>
			IPv4 listen IP address(es). You can specify either
			one or two addresses. If two addresses have been
			specified then rtpproxy will work in bridging mode.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-6</option> <replaceable>addr1<optional>/addr2</optional></replaceable></term>
		<listitem>
		    <para>
			IPv6 listen IP address(es). You can specify either one
			or two addresses. If two addresses have been specified
			then rtpproxy will work in bridging mode.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-s</option> <replaceable>ctrl_socket</replaceable></term>
		<listitem>
		    <para>
			This parameter configures rtpproxy control socket. The
			control socket is used by nathelper module of SER to 
			create/modify/delete RTP sessions to be relayed. 
			Format of <replaceable>ctrl_socket</replaceable> is 
			&lt;type&gt;:&lt;socket&gt;. Following types are
			supported:
			<itemizedlist>
			    <listitem>
				<para>
				    <emphasis>udp:</emphasis> Create UDP
				    control socket. In this mode RTPProxy will
				    listen on UDP for control messages from
				    SER/nathelper.
				</para>
				<para>
				    Example: -s udp:127.0.0.1:9000
				</para>
				<para>
				    IP address can be '*' in which case
				    rtpproxy will listen on all local
				    interfaces. If omitted port 22222 is used.
				</para>
				<note>
				    <para>
					RTPProxy control protocol has no
					built-in security mechanisms. Make sure
					that you protect the listening IP and
					port properly when using RTPProxy with
					UDP control socket.
				    </para>
				</note>
			    </listitem>
			    <listitem>
				<para>
				    <emphasis>udp6:</emphasis> Create IPv6 UDP
				    control socket. In this mode RTPProxy will
				    listen on UDP/IPv6 for control messages
				    from SER/nathelper.
				</para>
				<para>
				    Example: -s udp6:::1:9000
				</para>
			    </listitem>
			    <listitem>
				<para>
				    <emphasis>unix:</emphasis> Create UNIX
				    domain socket for control interface. In
				    this mode SER/nathelper and RTPProxy must
				    be running on the same host. This is the
				    default setting for both SER/nathelper and
				    rtpproxy.
				</para>
				<para>Example: -s unix:/var/run/rtpproxy.sock</para>
				<para>Default value is <filename>/var/run/rtpproxy.sock</filename>.</para>
			    </listitem>
			</itemizedlist>
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-t</option> <replaceable>tos</replaceable></term>
		<listitem>
		    <para>
			Set this ToS (Type of Service) in outgoing
			packets. Default value is 0xB8.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-r</option> <replaceable>rec_dir</replaceable></term>
		<listitem>
		    <para>Directory where recorded RTP sessions will be stored.</para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-S</option> <replaceable>spool_dir</replaceable></term>
		<listitem>
		    <para>
			Spool directory for RTP sessions being recorded. The
			file will be moved to directory configured in
			<option>-r</option> option after the session finishes.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-R</option></term>
		<listitem>
		    <para>
			Do not record RTCP when recording an RTP session. This
			option is disabled (rtpproxy will record RTCP) by default.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-p</option> <replaceable>pid_file</replaceable></term>
		<listitem>
		    <para>
			This parameter configures the name of the file where
			PID of running rtpproxy will be stored. Default is
			<filename>/var/run/rtpproxy.pid</filename>.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
		<term><option>-T</option> <replaceable>max_ttl</replaceable></term>
		<listitem>
		    <para>
			Limit the maximum TTL (Time To Live) of outgoing IP packets to
			the value of <replaceable>max_ttl</replaceable>.
		    </para>
		</listitem>
	    </varlistentry>
	    <varlistentry>
	        <term><option>-m</option> <replaceable>min_port</replaceable></term>
	        <listitem>
	            <para>
	                Set lower limit on UDP ports range that the RTPproxy uses for
	                RTP/RTCP sessions to <replaceable>min_port</replaceable>.
	                Default is 35000.
	            </para>
	        </listitem>
	    </varlistentry>
	    <varlistentry>
	        <term><option>-M</option> <replaceable>max_port</replaceable></term>
	        <listitem>
	            <para>
	                Set upper limit on UDP ports range that the RTPproxy uses for
	                RTP/RTCP sessions to <replaceable>max_port</replaceable>.
	                Default is 65000.
	            </para>
	        </listitem>
	    </varlistentry>
	    <varlistentry>
	        <term><option>-u</option> <replaceable>uname<optional>:gname</optional></replaceable></term>
	        <listitem>
	            <para>
	                Switch RTPproxy to UID identified by the <replaceable>uname</replaceable>
	                and optional GID identified by <replaceable>gname</replaceable> when
	                proxy is up and running.
	            </para>
	        </listitem>
	    </varlistentry>
	    <varlistentry>
	        <term><option>-F</option></term>
	        <listitem>
	            <para>
	                By default the RTPproxy will warn user if running as superuser (UID 0) in
	                local control mode and refuse to run in remote control mode at all.
	                This switch removes the check.
	            </para>
	        </listitem>
	    </varlistentry>
	</variablelist>
    </refsect1>

    <refsect1>
	<title>HowItWorks</title>
	<para>
	    When SER receives an INVITE request, it extracts Call-ID from it
	    and communicates it to rtpproxy via Unix domain socket or
	    UDP. Rtproxy looks for an existing session with such Call-ID. If
	    the session exists it returns UDP port for that session, if not,
	    then it creates a new session, binds to a first empty UDP port from
	    the range specified at the compile time and returns number of that
	    port to a SER. After receiving reply from the proxy, SER replaces
	    media ip:port in the SDP to point to the proxy and forwards request
	    as usually.
	</para>
	<para>
	    When SER receives a non-negative SIP reply with SDP it again extracts
	    Call-ID from it and communicates it to the proxy. In this case the proxy
	    does not allocate a new session if it doesn't exist, but simply performs a
	    lookup among existing sessions and returns either a port number if the
	    session is found, or error code indicating that there is no session with
	    such id. After receiving positive reply from the proxy, SER replaces media
	    ip:port in the SIP reply to point to the proxy and forwards reply as
	    usually.
	</para>
	<para>
	    After the session has been created, the proxy listens on the port
	    it has allocated for that session and waits for receiving at least
	    one UDP packet from each of two parties participating in the
	    call. Once such packet is received, the proxy fills one of two
	    ip:port structures associated with each call with source ip:port of
	    that packet. When both structures are filled in, the proxy starts
	    relaying UDP packets between parties.
	</para>
	<para>
	    The proxy tracks idle time for each of existing sessions (i.e. the time
	    within which there were no packets relayed), and automatically cleans
	    up a sessions whose idle times exceed the value specified at compile
	    time (60 seconds by default).
	</para>
    </refsect1>
    <refsect1>
	<title>FILES</title>
	<para>
	    <filename>/usr/sbin/rtpproxy</filename>
	</para>
    </refsect1>
    <refsect1>
	<title>LICENSE</title>
	<para>
	    This program is licensed under the BSD license. See
	    <filename>COPYING</filename> file in the rtpproxy sources for details.
	</para>
    </refsect1>

    <refsect1>
	<title>AVAILABILITY</title>
	<para>
	    The latest version of this program can be found at 
	    <ulink url="http://www.rtpproxy.org/">http://www.rtpproxy.org/</ulink>.
	</para>
    </refsect1>

    <refsect1>
	<title>SEEALSO</title>
	<para>ser(8).</para>
    </refsect1>
</refentry>