iptables

For anyone running a blog or a website with a comment section, spam in the comments is a vexed issue. Though there are tools for WordPress that already sort out the spam pretty well and pack it into a spam folder, these entries needs to be checked anyway, because you dont't want to accidentally delete a real comment, that landed in the spam folder for some reason.
This takes time and just annoying!

Luckily, there are some mmore options for you - at least, if you have a root access to your Linux server.