There is a lot of junk in the data we receive, so much that I find the s/n ratio too low without filtering out some of the noise, this page is dedicated to my filters.

Web - Mozilla ad blocking

Ads suck, flash sucks, flash ads suck badly, but Mozilla users need not fear as it's relatively easy to turn off both blinky-gif and flash where you don't want it (almost everywhere:) and with RIP (remove it permanently and Adblock.

Flash is evil and people who use it incorrectly (read: everyone who uses it) are mindless jerks who will be the first against the wall when the revolution comes.

Email - Postfix anti-virus

I use Linux, that means that I have nothing to fear from the outlook worms and windows viruses that make the world (more of) a living hell for windows users from time to time, but I still get lot's and lots of emails from infected windows machines that try to make my machine a fellow petridish.

Naturally this takes up a bunch of bandwidth and time, so I have installed a simple filter in my postfix server that simply rejects all mail that contains an attached windows executable, that effectively stops all windows viruses from getting into my mail box and because it filters on attachment contents rather than extention it will stay effective no matter what the filename is.

The filter works by looking for the base64 encoded start of a windows executable, which always looks the same.

To use this 100% secure anti-virus do:

  1. Use Postfix as your mail server.
  2. Create a body checks file: /etc/postfix/body_checks
  3. Put this line in it: /^TVqQAAMAAAAEAAA/ REJECT We do not have any windows machines here, so we have no use for windows executables, please convert the exefile to a standard format and re-send.
  4. And this: /<iframe/ REJECT Your email contains an iframe tag, which is often used by spammers and viruses, so I can't risk accepting the email.
  5. In put: body_checks = regexp:/etc/postfix/body_checks
  6. Have postfix reload the configuration files, run: postfix reload
  7. Enjoy your email free of all windows viruses.

I've written a small script to list the number of rejected mails: [12K] Use it like this: watch --interval=60 ./ /var/log/mail

© Flemming Frandsen