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merged docu corrections and improvements

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Gerhard Rieger 2009-05-06 20:02:56 +02:00
commit 2a34236fce
3 changed files with 66 additions and 13 deletions
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@ -15,6 +15,11 @@ corrections:
fixed a compile problem caused by size_t/socklen_t mismatch on 64bit
systems
docu mentions option so-bindtodev but correct name is so-bindtodevice.
Thanks to Jim Zimmerman for reporting.
added environment example to doc/socat-multicast.html
####################### V 1.7.1.0:
new features:

70
doc/socat-multicast.html
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@ -216,22 +216,25 @@ When you receive an error like:</p>
<table border="1" bgcolor="#e08080"><tr><td><tt>... E sendto(3, 0x80c2e44, 4,
0, AF=2 224.1.0.1:6666, 16): Network is unreachable</tt></td></tr></table>
<p>you have a routing problem. The (Linux) IP stack seems to handle multicast
addresses just like unicast addresses when determining their route (interface and gateway).</p>
addresses just like unicast addresses when determining their route (interface
and gateway), i.e. the routing table needs an entry that somehow matches the
target address. </p>
<p>
For the same reason, multicast packets will probably leave your host on the
interface with the default route.</p>
interface with the default route if it is specified.</p>
<p>
Set a multicast/broadcast route with the following command:</p>
Set a multicast/broadcast route with the following command (Linux):</p>
<span class="frame"><span class="shell">
route add -net 224.0.0.0/3 gw 192.168.10.2
</span></span>
<a name="ALLSYSTEMS">
<a name="ALLSYSTEMS"></a>
<h3>ALL-SYSTEMS multicast address</h3>
<p>
<tt>224.0.0.1</tt></a> is the all-systems multicast address: all
<tt>224.0.0.1</tt> is the all-systems multicast address: all
datagram sockets appear to be automatically member of this group on all
interfaces. This membership cannot be dropped on Linux.
interfaces. This membership cannot be dropped on Linux (you need iptables to
filter packets).
</p>
@ -240,11 +243,11 @@ interfaces. This membership cannot be dropped on Linux.
<p>When you use the above examples you should understand that all datagram
sockets without exception accept all packets that are directly addressed to
them;
the multi- and broadcast receiving features are just extensions to the normal
the multi- and broadcast receiving features are just extensions to this
functionality. socat currently has no means to handle incoming packets
differently when it is addressed to a unicast, multicast, or broadcast
address. However, for EXEC'd scripts socat can provide this info in environment
variables.
differently whether they are addressed to unicast, multicast, or broadcast
addresses. However, for EXEC'd scripts socat can provide this info in
environment variables.
</p>
<p>Authentication or encryption are not available.</p>
@ -301,7 +304,51 @@ Please note that the new features could not be successfully tested on IPv6;
these sections thus apply to IPv4 only.
</p>
<p>This document was last modified in April 2009.</p>
<h3>New Features in socat 1.7.0</h3>
<p>
socat version 1.7.0 helps to find more information about incoming packets in
environment variables that can be used in scripts or programs invoked by
socat. The option <tt>ip-pktinfo</tt> (on non-BSD systems)
or <tt>ip-recvdstaddr</tt> (on BSD systems) is required to get basic
information about incoming packets.
</p>
<p>
Example: Start a receiver of the following form (tried on Linux):
</p>
<span class="frame"><span class="shell">
socat -u udp-recvfrom:8888,reuseaddr,ip-add-membership=224.1.0.1:192.168.10.2,ip-pktinfo,fork system:export
</span></span>
<p>
Then send a multicast packet from the client:
</p>
<span class="frame"><span class="shell">
echo |socat -u - udp-datagram:224.1.0.1:8888
</span></span>
<p>
On the server the following text should appear (only interesting lines shown):
</p>
<pre>
export SOCAT_IP_DSTADDR="224.1.0.1"
export SOCAT_IP_IF="eth0"
export SOCAT_IP_LOCADDR="192.168.10.2"
export SOCAT_PEERADDR="192.168.10.1"
export SOCAT_PEERPORT="41159"
</pre>
<p>
<tt>SOCAT_IP_IF</tt> shows the interface where the packet entered the server;
<tt>SOCAT_IP_LOCADDR</tt> shows the IP address of this interface;
<tt>SOCAT_IP_DSTADDR</tt> shows the target address of the packet;
<tt>SOCAT_PEERADDR</tt> and <tt>SOCAT_PEERPORT</tt> are the client socket
values.
</p>
<h2>More info about socat datagrams</h2>
@ -336,6 +383,7 @@ with one peer address<br>
<a href="http://en.wikipedia.org/wiki/Broadcast_address">broadcasting on Wikipedia</a><br>
<p>
<small>This document was last modified in May 2009.</small><br>
<small>Copyright: Gerhard Rieger 2007-2009</small><br>
<small>License: <a href="http://www.fsf.org/licensing/licenses/fdl.html">GNU Free Documentation License (FDL)</a></small>
</p>

4
doc/socat.yo
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@ -10,7 +10,7 @@ def(Filan)(0)(bf(Filan))
def(procan)(0)(bf(procan))
def(Procan)(0)(bf(Procan))
manpage(socat)(1)(Apr 2009)()()
manpage(socat)(1)(May 2009)()()
whenhtml(
label(CONTENTS)
@ -1791,7 +1791,7 @@ label(OPTION_BIND)dit(bf(tt(bind=<sockname>)))
label(OPTION_CONNECT_TIMEOUT)dit(bf(tt(connect-timeout=<seconds>)))
Abort the connection attempt after <seconds> [link(timeval)(TYPE_TIMEVAL)]
with error status.
label(OPTION_SO_BINDTODEV)dit(bf(tt(so-bindtodev=<interface>)))
label(OPTION_SO_BINDTODEVICE)dit(bf(tt(so-bindtodevice=<interface>)))
Binds the socket to the given link(<interface>)(TYPE_INTERFACE).
This option might require root privilege.
label(OPTION_SO_BROADCAST)dit(bf(tt(broadcast)))