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Edit File: mod_dnsbl.html

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<title>ProFTPD module mod_dnsbl</title>
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<h2>ProFTPD module <code>mod_dnsbl</code></h2>
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A DNS blacklist is a way in which the DNS can be used to "blacklist"
sites/addresses that have been deemd to be "bad" in some way. These
blacklists are often used by email servers, for determining and rejecting
email sent by addresses known to be sources of spam. More information
on DNS blacklists can be found here:
<pre>
 <a href="http://en.wikipedia.org/wiki/DNSBL">http://en.wikipedia.org/wiki/DNSBL</a>
</pre>

While DNS blacklists are well known for use by email servers, it is also
possible to use them for other means, such as ways of checking whether an
FTP client's address should be allowed or rejected by an FTP server. Thus
the <code>mod_dnsbl</code> module was written for ProFTPD, for such a purpose.

This module is contained in the <code>mod_dnsbl.c</code> file for
ProFTPD 1.3.x, and is not compiled by default. Installation
instructions are discussed <a href="#Installation">here</a>.

The most current version of <code>mod_dnsbl</code> is distributed with the
ProFTPD source code.

<h2>Author</h2>

Please contact TJ Saunders &lt;tj at castaglia.org&gt; with any
questions, concerns, or suggestions regarding this module.

<h2>Directives</h2>
<ul>
 <li><a href="#DNSBLDomain">DNSBLDomain</a>
 <li><a href="#DNSBLEngine">DNSBLEngine</a>
 <li><a href="#DNSBLLog">DNSBLLog</a>
 <li><a href="#DNSBLPolicy">DNSBLPolicy</a>
</ul>

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<h2><a name="DNSBLDomain">DNSBLDomain</a></h2>
Syntax: DNSBLDomain domain 
Default: None 
Context: server config, <code>&lt;VirtualHost&gt;</code>, <code>&lt;Global&gt;</code> 
Module: mod_dnsbl 
Compatibility: 1.3.1rc1 and later

The <code>DNSBLDomain</code> directive is used to configure the DNS name of
a DNS blacklist site, to be consulted when determining whether
<code>mod_dnsbl</code> should allow or reject an FTP connection. This
directive can be used multiple times, to configure multiple different DNS
blacklist sites. When checking these sites, the <code>mod_dnsbl</code> module
will check each <code>DNSBLDomain</code>, in the order they appear in the
<code>proftpd.conf</code> file.

Example:
<pre>
 DNSBLDomain sbl.spamhaus.org
 DNSBLDomain xbl.spamhaus.org
</pre>

<hr>
<h2><a name="DNSBLEngine">DNSBLEngine</a></h2>
Syntax: DNSBLEngine on|off 
Default: None 
Context: server config, <code>&lt;VirtualHost&gt;</code>, <code>&lt;Global&gt;</code> 
Module: mod_dnsbl 
Compatibility: 1.3.1rc1 and later

The <code>DNSBLEngine</code> directive toggles the use of DNS blacklists for
access control for FTP client connections (e.g. <code>mod_dnsbl</code>).
This is usually used inside a <code>&lt;VirtualHost&gt;</code> section to
enable DNS blacklist use for a particular virtual host. By default
<code>mod_dnsbl</code> is disabled for both the main server and all configured
virtual hosts.

<hr>
<h2><a name="DNSBLLog">DNSBLLog</a></h2>
Syntax: DNSBLLog file 
Default: None 
Context: server config, <code>&lt;VirtualHost&gt;</code>, <code>&lt;Global&gt;</code> 
Module: mod_dnsbl 
Compatibility: 1.3.1rc1 and later

The <code>DNSBLLog</code> directive is used to specify a log file for
<code>mod_dnsbl</code>'s reporting on a per-server basis. The file
parameter given must be the full path to the file to use for logging.

Note that this path must not be to a world-writable directory and,
unless <code>AllowLogSymlinks</code> is explicitly set to on
(generally a bad idea), the path must not be a symbolic link.

<hr>
<h2><a name="DNSBLPolicy">DNSBLPolicy</a></h2>
Syntax: DNSBLPolicy "allow,deny"|"deny,allow" 
Default: None 
Context: server config, <code>&lt;VirtualHost&gt;</code>, <code>&lt;Global&gt;</code> 
Module: mod_dnsbl 
Compatibility: 1.3.1rc1 and later

The <code>DNSBLPolicy</code> directive determines whether the
<code>mod_dnsbl</code> module (if enabled) will allow a connection by default
or not.

If <code>DNSBLPolicy</code> is configured using "allow,deny", then
the <code>mod_dnsbl</code> module will allow the connection, unless
the connecting client is blacklisted by any of the configured
<code>DNSBLDomain</code> sites.

If <code>DNSBLPolicy</code> is configured using "deny,allow", then
the <code>mod_dnsbl</code> module will not allow the connection,
unless the connecting client is listed by any of the configured
<code>DNSBLDomain</code> sites.

<hr> 
<h2><a name="Installation">Installation</a></h2>
After unpacking the <code>mod_dnsbl</code> tarball, move the directory into
the ProFTPD source directory:
<pre>
 mv mod_dnsbl/ /path/to/proftpd/contrib/
</pre>
Note that it is necessary to move the entire <code>mod_dnsbl</code>
directory, not just the <code>mod_dnsbl.c</code> source file, into the
<code>contrib/</code> directory in the ProFTPD source directory. Failure to
do so will result in a failed build.

Next:
<pre>
 cd /path/to/proftpd/contrib/mod_dnsbl/
 ./configure
</pre>
This step is also necessary. If not done, then the proftpd build system
will not pick up the correct linker flags for the resolver library.

Then follow the normal steps for using third-party modules in proftpd:
<pre>
 ./configure --with-modules=mod_dnsbl
 make
 make install
</pre>

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Author: $Author: castaglia $ 
Last Updated: $Date: 2013-09-18 21:18:51 $

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