Provided by: rtpproxy_1.2.1-2.1ubuntu1_amd64 
NAME
rtpproxy - RTP (Real-time Transport Protocol) Proxy Server
SYNOPSIS
rtpproxy [-?] [-2] [-f] [-v] [-R] [-l addr1[/addr2]] [-6 addr1[/addr2]] [-s ctrl_socket]
[-t tos] [-p pidfile] [-T max_ttl] [-r rdir [-S sdir]] [-m min_port]
[-M max_port] [-u uname[:gname]] [-F] [-i] [-n timeout_socket] [-P] [-a]
[-d log_level[:log_facility]]
DESCRIPTION
rtpproxy 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.
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.
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.
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).
OPTIONS
-?
Show summary of options.
-2
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.
-f
Rtpproxy will stay in foreground mode if this option is set.
-v
Show version of program.
-l addr1[/addr2]
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.
-6 addr1[/addr2]
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.
-s ctrl_socket
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
ctrl_socket is <type>:<socket>. Following types are supported:
• udp: Create UDP control socket. In this mode RTPProxy will listen on UDP for
control messages from SER/nathelper.
Example: -s udp:127.0.0.1:9000
IP address can be ´*´ in which case rtpproxy will listen on all local interfaces.
If omitted port 22222 is used.
Note
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.
• udp6: Create IPv6 UDP control socket. In this mode RTPProxy will listen on
UDP/IPv6 for control messages from SER/nathelper.
Example: -s udp6:::1:9000
• unix: 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.
Example: -s unix:/var/run/rtpproxy.sock
Default value is /var/run/rtpproxy.sock.
-t tos
Set ToS (Type of Service) in the outgoing UDP packets to this value. Default value
is 0xB8. Setting this parameter to -1 disables setting ToS resulting in operating
system default ToS being used instead.
-r rec_dir
Directory where recorded RTP sessions will be stored.
-S spool_dir
Spool directory for RTP sessions being recorded. The file will be moved to
directory configured in -r option after the session finishes.
-R
Do not record RTCP when recording an RTP session. This option is disabled
(rtpproxy will record RTCP) by default.
-p pid_file
This parameter configures the name of the file where PID of running rtpproxy will
be stored. Default is /var/run/rtpproxy.pid.
-T max_ttl
Limit the maximum TTL (Time To Live) of outgoing IP packets to the value of
max_ttl.
-m min_port
Set lower limit on UDP ports range that the RTPproxy uses for RTP/RTCP sessions to
min_port. Default is 35000.
-M max_port
Set upper limit on UDP ports range that the RTPproxy uses for RTP/RTCP sessions to
max_port. Default is 65000.
-u uname[:gname]
Switch RTPproxy to UID identified by the uname and optional GID identified by
gname when proxy is up and running.
-F
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.
-i
Enable independent timeout mode. By default, a timeout (which results in automatic
destruction of the session) can only occur if no RTP packets are received on any
of the session´s ports. This option if set varies that behaviour, such that a
timeout will occur if packets are still being received on one port but not the
other. The option should be used with caution since in some cases it´s perfectly
fine to have packets coming from only one side of conversation (i.e. when the
second party has muted its audio).
-n timeout_socket
This parameter configures the optional timeout notification socket. The socket
should be created by another application, preferably before starting rtpproxy. For
those sessions where the timeout mechanism is enabled, notifications are sent on
this socket if the session times out.
Example: -n unix:/var/run/rtpproxy_timeout.sock
There is no default value, notifications are not sent and not permitted unless a
value is specified explicitly.
-P
Record sessions using PCAP file format instead of non-standard ad-hoc format. The
PCAP format, which is the de-facto standard for packet capturing software, has the
advantage of being compatible with numerous third-party tools and utilities, such
as Wireshark (Ethereal) for example. The drawback of PCAP is sligtly larger
overhead (extra 12 bytes for every saved RTP packet for IPv4). Also, recording
IPv6 sessions in PCAP format is not supported at the moment.
-a
Record all sessions going through the RTPproxy unconditionally. By default the
RTPproxy requires call control software (i.e. SER, OpenSER or B2BUA) to enable
recording explicitly on per-session basis by sending appropriate record command.
-d log_level[:log_facility]
This parameter configures the verbosity level of the log output. Possible
log_level values in the order from the most verboe to the least verbose are: DBUG,
INFO, WARN, ERR and CRIT.
The optional log_facility parameter sets syslog(3) facility assigned to log
messages.
Example: -d WARN:LOG_LOCAL5
The default level in foreground mode is is DBUG, in background - WARN and facility
is LOG_DAEMON.
HOWITWORKS
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.
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.
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.
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).
FILES
/usr/sbin/rtpproxy
LICENSE
This program is licensed under the BSD license. See COPYING file in the rtpproxy sources
for details.
AVAILABILITY
The latest version of this program can be found at http://www.rtpproxy.org/.
SEEALSO
ser(8).
AUTHOR
Maxim Sobolev
Author.
COPYRIGHT
CopyrightCopyright © 2006 janakj
[FIXME: source] Jun 16, 2008 RTPPROXY(8)