Tuesday, March 20, 2007

Linux-Pro #76

I got myself a copy of the Linux Pro March issue.
In my opinion, it is extremely interesting. First, as you can see, the DVD is the Best of Small Distros. Now, in addition to the mere idea of fitting 11 different distros on one DVD-ROM being cool, the actual distros are extremely useful. By far, my favorite is Puppy Linux. It's extremely easy to use and can even function as a hard drive if used in the right way. If you burn Puppy Linux as a multi-session disc, you can keep writing to it and keep your data. Since it's so portable, you can carry it around and use any computer lying around. In my opinion, that's really cool. Of course, the next best thing is Damn Small Linux (DSL). It's not as "cute" as Puppy Linux, or as comprehensive, but it's 50 MB. That's amazing. There are also others, but they're "meh".

The main topic of this issue is spam, and there are some pretty cool articles about it. One of my favorites is about tarpits. One way to combat spiders, which scour the internet for loose e-mail addresses is with the use of tarpits. Tarpits are basically links which link to more links, which in turn link to more links. This would make a spider extremely confused and disoriented. However, computers have gotten so powerful that the connection caught in the tarpit is negligible. However, some spiders now have time-out restrictions so they wouldn't get caught in a tarpit. Luckily, if they leave the tarpit before they get your e-mail, that's less spam for you.

The last cool tool I'm going to talk about is about spamd in OpenBSD. This is, in my opinion, the coolest of the cool. At first, spamd comes with a whitelist of trusted domains. However, other domains are greylisted, in that it is not known whether they are good or bad. There are several strategies spamd uses for greylisted messages. One thing is that it sends a "Temporarily Unavailable" error to the sending server. If the sending server does not retry, it probably belongs to a spammer, and the domain is blacklisted. The way spamd deals with blacklisted (and sometimes greylisted) domains is that it artificially slows down the connection. If the sending server was a spammer, it would think it was caught in a tarpit and terminate the connection. This means no spam for you.

No comments: