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<TITLE>The Answer Gang 87: filter out spam and viruses</TITLE>
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<H3 align="left"><img src="../../gx/dennis/bbubble.gif"
height="50" width="60" alt="(!) " border="0"
>filter out spam and viruses</H3>
<p><strong>From Jonathan Becerra
</strong></p>
<p align="right"><strong>Answered By Faber Fedor, Neil Youngman, Kapil Hari Paranjape, Heather Stern
<p></strong></p>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
I'm very new to Linux but like what I see
</STRONG></P>
<P><STRONG>
The object here is to install a software that will filter all my e-mails and
keep out viruses
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Faber]
Look into Amavis (www.amavis.org) and your favorite anti-virus software
(Sophos, McAffee, etc.). If you're using Postfix as your MTA, drop me a
line and I can help you get the three of them working.
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
and catch re-occurring spam.
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Faber]
Check out Spam Assassin (www.spamassassin.org). It rocks!
</blockQuote>
<blockquote><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Heather] Since the list which all Answer Gang members are on uses SpamAssassin as one
among several defenses, I think yes - it does
<IMG SRC="../../gx/dennis/smily.gif" ALT=":)"
height="24" width="20" align="middle"> but it is not infallible.
With any mail filtering answers I encourage you to take a look at its
principles, and decide if you like them, rather than just take someone
else's word on what is or isn't spam.
</blockquote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Neil]
LWN seem to rate bogofilter, see <A HREF="http://lwn.net/Articles/9186"
>http://lwn.net/Articles/9186</A>. I haven't
used it myself.
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Kapil]
I currently use "bogofilter" and am very happy with it. There are also
alternatives such as "spamoracle" and "spamprobe". All these three
programs implement Paul Graham's suggestions in "A Plan for Spam".
</blockQuote>
<blockQuote>
As far as I can make out "spamassasin" is a much more general tool that
can easily incorporate the measurements used by Paul Graham.
</blockQuote>
<blockQuote>
The neatness of Paul Graham's approach is that it is entirely
"Bayesian" --- spam mails self-select themselves once we have a
sufficiently large database of spam and non-spam messages. Moreover,
this division is entirely in the hands of the end-user.
</blockQuote>
<blockQuote>
On the other hand since this measurement is made <EM>after</EM> the mail enters
the system it is not very useful if you want to reduce bandwidth
consumption.
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
I have 2 NIC cards, etho1 and
etho2. Both were picked up by my install and both work, I can get out to the
Internet with either one. I need help configuring etho1 to be the incoming
route for my e-mails which my software will then pick up and process and
then I want etho2 to send it out to my users.
</STRONG></P>
<P><STRONG>
I have been all over the Internet and in the book stores, I even had to
break down and buy a Linux book for dummies which was no help at all.
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Kapil]
I think what you need is to take a hard look at Firewall-HOWTO.
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Faber]
(at <A HREF="http://www.tldp.org"
>http://www.tldp.org</A>, in case you didn't know).
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
Sound possible?
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Faber]
With Linux, almost anything is possible.
</blockQuote>
<blockquote><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Heather] Though it may take a while to finish coding... no wait, that's "the
impossible takes a little longer"
<IMG SRC="../../gx/dennis/smily.gif" ALT=":D"
height="24" width="20" align="middle">
</blockquote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
I would be so appreciative and so would my head (because then I can quit
banging it against my desk) for any and all help you could provide.
</STRONG></P>
<blockquote><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
> [Heather] On behalf of the Gang, we hope you heal up soon! You're following good
principles; make all emails have to follow one path into your site,
then place some guardians upon that path to nail the miscreants as they
come through.
</blockquote>
<blockquote>Tune up your firewall to only show services to the outside world which
you really provide, and that needed for your inside people to get to
outside services they use (generally, using IP masquerading will make
this automatic and nearly invisible). If you've got specific hosts
pestering you with spam, get your MTA to blow them off with a "551
too much spam, site blocked" so your mailbox guardians don't have to
waste CPU time on those bozos. Best of luck in the battle against spam.
</blockquote>
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<br>Copyright &copy; 2003
<br>Copying license <A HREF="">http://www.linuxgazette.com/copying.html</A>
<BR>Published in Issue 87 of <i>Linux Gazette</i>, February 2003</H5>
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