1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
|
<?xml version='1.0' encoding='ISO-8859-1'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY dhfirstname "<firstname>Maxim</firstname>">
<!ENTITY dhsurname "<surname>Sobolev</surname>">
<!-- Please adjust the date whenever revising the manpage. -->
<!ENTITY dhdate "<date>Feb 20, 2006</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>sobomax@PBXpress.com</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>
</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 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
<type>:<socket>. 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>
</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://ftp.iptel.org/pub/rtpproxy">http://ftp.iptel.org/pub/rtpproxy</ulink>.
</para>
</refsect1>
<refsect1>
<title>SEEALSO</title>
<para>ser(8).</para>
</refsect1>
</refentry>
|
