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242 lines
8.3 KiB
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<title>RINETD(8)</title>
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<body bgcolor="#FFFFF0">
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Copyright (c) 1997, 1998, 1999, Thomas Boutell and Boutell.Com, Inc.
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This software is released for free use under the terms of
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the GNU General Public License, version 2 or higher.
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-->
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<table>
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<tr>
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<th width=33% align=left>RINETD(8)
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<th width=33% align=right>Unix System Manager's Manual
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<th width=33% align=right>RINETD(8)
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</tr>
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</table>
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<p>
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<font color="#FF8888" size="4">NAME</font>
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<p>
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rinetd -- internet ``redirection server''
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<p>
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<font color="#FF8888" size="4">SYNOPSIS</font>
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<p>
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<code>/usr/sbin/rinetd</code>
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<p>
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<font color="#FF8888" size="4">VERSION</font>
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<p>
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Version 0.62, 04/13/2003. Version 0.62 corrects a potential
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buffer overflow when reallocating memory to accommodate more
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connections. Upgrading is strongly recommended.
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<p>
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<font color="#FF8888" size="4">WHERE TO GET</font>
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<p>
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<strong>For Linux:</strong>
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<a href="ftp://ftp.boutell.com/pub/boutell/rinetd/rinetd.tar.gz">By
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anonymous FTP from ftp.boutell.com</a> in the subdirectory
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<code>boutell/rinetd</code> as the file <code>rinetd.tar.gz</code>.
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<p>
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<strong>For Windows 95/98/NT:</strong>
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<a href="ftp://ftp.boutell.com/pub/boutell/rinetd/rinetd.zip">By
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anonymous FTP from ftp.boutell.com</a> in the subdirectory
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<code>boutell/rinetd</code> as the file <code>rinetd.zip</code>.
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<p>
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<font color="#FF8888" size="4">DESCRIPTION</font>
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<p>
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Redirects TCP connections from one IP address and port to another. rinetd
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is a single-process server which handles any number of connections to
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the address/port pairs specified in the file <code>/etc/rinetd.conf</code>.
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Since rinetd runs as a single process using nonblocking I/O, it is
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able to redirect a large number of connections without a severe
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impact on the machine. This makes it practical to run TCP services
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on machines inside an IP masquerading firewall. rinetd <strong>does not
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redirect FTP,</strong> because FTP requires more than one socket.
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<p>
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rinetd is typically launched at boot time, using the following syntax:
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<p>
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<code>/usr/sbin/rinetd</code>
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<p>
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The configuration file is found in the file
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<code>/etc/rinetd.conf</code>, unless
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another file is specified using the <code>-c</code> command line option.
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<p>
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<font color="#FF8888" size="4">FORWARDING RULES</font>
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<p>
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Most entries in the configuration file are forwarding rules. The
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format of a forwarding rule is as follows:
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<pre>
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bindaddress bindport connectaddress connectport
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</pre>
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For example:
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<pre>
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206.125.69.81 80 10.1.1.2 80
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</pre>
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Would redirect all connections to port 80 of the "real" IP address
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206.125.69.81, which could be a virtual interface, through
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rinetd to port 80 of the address 10.1.1.2, which would typically
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be a machine on the inside of a firewall which has no
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direct routing to the outside world.
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<p>
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Although responding on individual interfaces rather than on all
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interfaces is one of rinetd's primary features, sometimes it is
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preferable to respond on all IP addresses that belong to the server.
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In this situation, the special IP address <code>0.0.0.0</code>
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can be used. For example:
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<pre>
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0.0.0.0 23 10.1.1.2 23
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</pre>
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Would redirect all connections to port 23, for all IP addresses
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assigned to the server. This is the default behavior for most
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other programs.
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<p>
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Service names can be specified instead of port numbers. On most systems,
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service names are defined in the file /etc/services.
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<p>
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Both IP addresses and hostnames are accepted for
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bindaddress and connectaddress.
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<p>
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<font color="#FF8888" size="4">ALLOW AND DENY RULES</font>
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<p>
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Configuration files can also contain allow and deny rules.
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<p>
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Allow rules which appear before the first forwarding rule are
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applied globally: if at least one global allow rule exists,
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and the address of a new connection does not
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satisfy at least one of the global allow rules, that connection
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is immediately rejected, regardless of any other rules.
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<p>
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Allow rules which appear after a specific forwarding rule apply
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to that forwarding rule only. If at least one allow rule
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exists for a particular forwarding rule, and the address of a new
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connection does not satisfy at least one of the allow rules
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for that forwarding rule, that connection is immediately
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rejected, regardless of any other rules.
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<p>
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Deny rules which appear before the first forwarding rule are
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applied globally: if the address of a new connection satisfies
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any of the global allow rules, that connection
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is immediately rejected, regardless of any other rules.
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<p>
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Deny rules which appear after a specific forwarding rule apply
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to that forwarding rule only. If the address of a new
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connection satisfies any of the deny rules for that forwarding rule,
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that connection is immediately rejected, regardless of any other rules.
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<p>
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The format of an allow rule is as follows:
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<pre>
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allow pattern
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</pre>
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Patterns can contain the following characters: 0, 1, 2, 3, 4, 5,
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6, 7, 8, 9, . (period), ?, and *. The ? wildcard matches any one
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character. The * wildcard matches any number of characters, including
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zero.
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<p>
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For example:
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<p>
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<pre>
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allow 206.125.69.*
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</pre>
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This allow rule matches all IP addresses in the 206.125.69 class C domain.
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<p>
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Host names are NOT permitted in allow and deny rules. The performance
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cost of looking up IP addresses to find their corresponding names
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is prohibitive. Since rinetd is a single process server, all other
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connections would be forced to pause during the address lookup.
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<p>
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<font color="#FF8888" size="4">LOGGING</font>
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<p>
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rinetd is able to produce a log file in either of two formats:
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tab-delimited and web server-style "common log format."
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<p>
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By default, rinetd does not produce a log file. To activate logging, add
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the following line to the configuration file:
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<pre>
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logfile log-file-location
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</pre>
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Example:
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<pre>
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logfile /var/log/rinetd.log
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</pre>
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By default, rinetd logs in a simple tab-delimited format containing
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the following information:
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<p>
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Date and time<br>
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Client address<br>
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Listening host
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<br>
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Listening port
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<br>
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Forwarded-to host
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<br>
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Forwarded-to port
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<br>
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Bytes received from client
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<br>
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Bytes sent to client
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<br>
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Result message
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<p>
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To activate web server-style "common log format" logging,
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add the following line to the configuration file:
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<pre>
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logcommon
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</pre>
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<p>
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<font color="#FF8888" size="4">COMMAND LINE OPTIONS</font>
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<p>
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The -c command line option is used to specify an alternate
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configuration file.
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<p>
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The -h command line option produces a short help message.
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<p>
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The -v command line option displays the version number.
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<p>
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<font color="#FF8888" size="4">REINITIALIZING RINETD</font>
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<p>
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The kill -1 signal (SIGHUP) can be used to cause rinetd
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to reload its configuration file <strong>without</strong> interrupting existing
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connections. Under Linux(tm) the process id
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is saved in the file <code>/var/run/rinetd.pid</code>
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to facilitate the kill -HUP. An alternate
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file name can be provided by using the <code>pidlogfile</code>
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configuration file option.
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<p>
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<font color="#FF8888" size="4">BUGS</font>
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<p>
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The server redirected to is not able to identify the host the
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client really came from. This cannot be corrected; however,
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the log produced by rinetd provides a way to obtain this
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information. Under Unix, sockets would theoretically lose data when closed
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with <code>SO_LINGER</code> turned off, but in Linux this is not the case
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(kernel source comments support this belief on my part). On non-Linux Unix
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platforms, alternate code which uses a different trick to work around
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blocking <code>close()</code> is provided, but this code is untested.
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<p>
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The logging is inadequate. The duration of the connection should be logged.
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<p>
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<font color="#FF8888" size="4">LICENSE</font>
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<p>
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Copyright (c) 1997, 1998, 1999,
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<a href="http://www.boutell.com/boutell">Thomas Boutell</a> and
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<a href="http://www.boutell.com/">Boutell.Com, Inc.</a>
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This software is released for free use under the terms of
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the GNU General Public License, version 2 or higher.
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<p>
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<font color="#FF8888" size="4">CONTACT INFORMATION</font>
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<p>
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See <a href="http://www.boutell.com/rinetd">the rinetd web page</a>
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for the latest release.
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Thomas Boutell can be reached by email:
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<a href="mailto:boutell@boutell.com">boutell@boutell.com</a>
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<p>
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<font color="#FF8888" size="4">THANKS</font>
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<p>
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Thanks are due to Bill Davidsen, Libor Pechachek, Sascha Ziemann,
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Joel S. Noble, the Apache Group, and many others who have contributed
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advice, encouragement and/or source code to this and other open
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software projects.
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</body>
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</html>
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