Combating Spam and Bots

Google lets you put any number of periods in your gmail address, and it ignores all of them when receiving mail for you.

Try it; it's fun!

Spammers have taken advantage of this, unfortunately, to spam more and more easily.

If you see a Gmail address with about as many periods as letters, it is probably a spammer. If that address turns up twice, differing only by the number or placement of periods, it is pretty certainly a spammer.

Hi,

I have a private site which is undergoing a massive attack (without success, already mentioned here: http://drupal.org/node/811734).
An answer was to set up a small javacript that sets a variable and if a robot visits the javascript won't be triggered.
I could then test for the variable & if not set then don't display the comment form.

How would I do that?
Any help is appreciated.

I came up with a simple snippet to block a huge amount of anonymous comment spam that I'd like to share. I made a rule that anonymous users cannot include links in their comments. I don't believe that this is much of an inconvenience to legitimate visitors. They can still paste a URL into their comment, it just won't be hyperlinked.

Here's the code (from a module called fiercecommon that contains a common functions used across our sites -- you can put it wherever):
<?php
/**
* Implementation of hook_comments() -- Blocks anon comment spam by preventing posts with link tags!
*/

In my experience as a Drupal site admin and webmaster, I've found only one way to absolutely prevent spam on two of my sites: require payment of a a subscription fee before allowing users to post new content.

As you can imagine, this has stopped spammers in their tracks. No spammer will ever pay a dime to post spam, it seems. Of course, new content postings have dropped significantly, as well!

One of my low-traffic sites was hit with significant trackback spam. We found out when we were notified by our hosting provider of a significant bandwidth overage for the month.

The spam module was doing a great job of keeping the spam out, but due to the flood of trackback requests during a sustained period, we experienced a massive increase in traffic.

I have now disabled trackbacks on that site (ti's the only site I had set up to allow trackbacks) and have enabled the spam module's "Trackback Black Hole" module so that all trackback requests are dropped immediately.

I'm also getting hit by nareman trying to unsuccessfully log in. I've managed to block 90% of it with mod_rewrite, but the changing bot will make that time consuming to keep up with.

Anyway, is there any way to filter POST data (in Apache - I don't want to invoke Drupal for this). I'm in no position to write an Apache filter, and not keen on installing mod_security for various reasons. Is there any way of getting mod_rewrite to match on POST data?

I'm almost tempted to start looking at IDS style tools that can update my firewall rulesets (ouch).