plugin-patterns.html

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<h2><a href="mailfront.html">MailFront</a></h2>
<h2><a href="smtpfront.html">SMTP Front Ends</a></h2>

<h1>Plugin: patterns</h1>

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<p>This module provides an ability for rejecting messages based on
simple patterns in their content.<p>

<h2>Configuration</h2>

<dl>

<dt><tt>$PATTERNS</tt></dt> <dd>If set, the named file is loaded and
parsed (see below), and pattern matching is enabled.</dd>

<dt><tt>$PATTERNS_LINEMAX</tt></dt> <dd>Line buffer size (defaults to
256)</dd>

<dt><tt>$PATTERNS_RESP</tt></dt> <dd>Response message to give when a
pattern is matched (defaults to "<tt>This message contains
prohibited content</tt>")</dd>

</dl>

<h2>Sender Action</h2>

<p>None</p>

<h2>Recipient Action</h2>

<p>None</p>

<h2>Data Action</h2>

<p>Each line of the data sent from the client is loaded into a line
buffer (with a maximum size as above) and then scanned against the
patterns listed in the configuration file.  If any pattern matches, the
message is rejected.</p>

<h2>Message Action</h2>

<p>None</p>

<h2>Patterns File Format</h2>

<p>The patterns file contains a list of standard glob-style patterns.
Each line of the file starts with a control character, which is
<i>not</i> part of the pattern itself:</p>

<dl>

<dt><tt>#</tt></dt> <dd>Comment line, ignored.</dd>

<dt><tt>=</tt></dt> <dd>Sets the response text given when a message is
rejected.  All following patterns use this response until the next
response line.  Including this in the patterns file overrides the value
of <tt>$PATTERNS_RESP</tt>.</dd>

<dt><tt>:</tt></dt> <dd>The pattern will be applied only in the
header.</dd>

<dt><tt>\</tt></dt> <dd>The pattern will be applied only after a blank
line.</dd>

<dt>Anything else</dt> <dd>A normal pattern, applied to any non-blank
line.</dd>

</dl>

<p>The following patterns list is a much simplified version of Russell
Nelson's <a
href="http://qmail.org/qmail-smtpd-viruscan-1.1.patch">qmail-smtpd virus
scan patch</a>.  In particular, it doesn't actually do any kind of
checking if the blank line really marked a MIME boundary or not.</p>

<pre>
=We don't accept email with executable content (#5.3.4)
\TVqQAAMAA*
\TVpQAAIAA*
\TVpAALQAc*
\TVpyAXkAX*
\TVrmAU4AA*
\TVrhARwAk*
\TVoFAQUAA*
\TVoAAAQAA*
\TVoIARMAA*
\TVouARsAA*
\TVrQAT8AA*
\TVoAAAEAAA*
</pre>

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