six demon bag

Wind, fire, all that kind of thing!

2021-04-24

Registration Blocker 1.6.0 released

There are some recurring patterns spammers use for their e-mail addresses, so I added a regular expression filter to the Registration Blocker plugin for Question2Answer.

Download: Version 1.6.0

Posted 13:53 [permalink]

2020-06-11

Installing Discourse on Devuan

Before deciding on setting up my Q&A site with Question2Answer I evaluated several programs, one of them being Discourse. And even though I ultimately decided against Discourse (because the setup was too complex and it doesn't have all the features I wanted) I don't want my experiences go to waste, so I'll publish them here.

See more ...

Posted 19:57 [permalink]

2010-05-30

Backscatter protection

What is backscatter?

When mail servers accept mail and later discover that for some reason they are unable to actually deliver it, RFC 821 specifies that a Non-Delivery Notification (NDN, also known as "bounce") must be sent to the originator of the mail.

However, the "From" address can be spoofed most easily, so there is no guarantee whatsoever that the mail actually originated from that address. In case of a spoofed address, the NDN will be sent to someone who hadn't sent the original mail to begin with. These bounces going back to someone else but the original sender are called "backscatter".

Why is that a problem?

Because spammers tend to send their bulk e-mails to anything that looks even remotely like an e-mail address, the "To" addresses usually include lots of invalid addresses. Therefore spam-runs can cause massive waves of backscatter flooding the mailboxes of those people whose addresses were spoofed in the "From" field. However, it's not sensible to simply block all incoming bounces, because there are legitimate bounces as well.

See more ...

Posted 22:41 [permalink]

2009-01-29

Mail Encryption Proxy

A quick & dirty Perl script written by Alexander Bernauer and myself, because we needed our ticket system to be able to send encrypted mail.

Posted 17:13 [permalink]