funsec mailing list archives
Spamhaus for Extra Mail Server Security
From: Gadi Evron <ge () linuxbox org>
Date: Sat, 12 Sep 2009 02:42:41 +0300
Here's something I recently wrote, which I'd like to share with you. Spamhaus For Extra Mail Server Security Posted by Gadi Evron, Sep 10, 2009 04:26 PM Spamhaus, the anti-spam organization, provides a reliable list of compromised computers -- bots -- used to send spam. This list can be used as an extra layer of security for your email server, among other purposes. By filtering with this blacklist, millions of mail servers worldwide manage to stay operational. At the same time, email remains a viable communication medium in spite of the load spam emails put on the infrastructure. There's never a good time to discover you can't use email, especially while flying around the world on business. This recently happened to me; I was unable to send email, and the error message baffled me. It claimed my IP address was on the Spamhaus ZEN blacklist. Blacklisting is supposed to be enabled only for other servers trying to connect to mine, so why was the server blocking me, a user, when I authenticated and tried to email? Turns out the problem was due to a configuration error. But I liked it; the bug became a feature. Because I'm among very few users using this server, the inconvenience was negligible. If I am willing to not email while connecting via insecure networks, then I gain an extra layer of security. Millions of bot-infected computers are far less likely to be successful in compromising the server because they can't access much of its functionality. Given that most Internet attacks are performed via bots, I feel this raises the security level of the server at the price of being slightly inconvenienced when on the road. I cannot IP filter an SMTP server to be available only from certain locations -- as if I even wanted to limit myself in such a way. By its very nature as a public service, it needs to be available to the world if I am to receive email from others. And this extra security helps increase my assurance level. This solution won't work for everybody. Perhaps you are not willing to inconvenience yourself, or perhaps you use a busier server and can't decide on such a measure for the other users. But it works for me. Of course, there are many varied solutions for secure email. This bug-become-feature just made mine better. _______________________________________________ Fun and Misc security discussion for OT posts. https://linuxbox.org/cgi-bin/mailman/listinfo/funsec Note: funsec is a public and open mailing list.
Current thread:
- Spamhaus for Extra Mail Server Security Gadi Evron (Sep 11)
- Re: Spamhaus for Extra Mail Server Security Rich Kulawiec (Sep 14)