Defeating Comment Spam Bots

Here’s how I dropped virtually all of my comment spam, with no extra challenge fields to hinder human commenters.

no spam logo by david hegarty

logo by David Hegarty (License: Creative Commons Attribution-NonCommercial 2.0 Generic)

I hate spam. I don’t mean the  canned Hormel pork product that is so tasty in Spam musubi or Spam fried rice. I mean all the unwanted comments and links to any manner of dubious websites invading this blog’s  comments section.

House of Annie is a WordPress-powered blog that used to get a moderate amount of comment spam. Spambots – computers run by spammers to automatically leave comments on blogs – were becoming an increasing nuisance. Like most WordPress blog owners, I use the Akismet anti-spam plugin as my first line of defense against comment spam.

But sometimes Akismet either lets a spam comment through or shunts a legitimate comment over to the Spam queue (a “false positive”). That’s why I moderate comments as well, only letting previously approved commenters get automatic posting privileges. It’s a second line of defense for the ones that gets past Akismet, but doesn’t help with false positives that may be sitting in the Spam queue.

If there are a lot of comments in the spam queue, it’s not so easy to find these false positives. It’s almost like finding a needle in a haystack. As this blog has gotten more popular, that haystack has gotten bigger. I needed to find a way to reduce the comment spam, but did not want to use CAPTCHA or math challenge-response plugins that stop spambots but slow down human commenters.

I think I found my answer.


NoSpamNX Settings

NoSpamNX is a simple, small plugin that doesn’t require Javascript on the browser or editing the comments template to work. All you have to do is install and enable it, and it goes to work! It automatically adds hidden fields to the comment form, which normal humans cannot see but spambots do. If these hidden fields are filled, the comment is assumed to be spam, and blocked.

As you can see by my Akismet stats, spam comments have dropped off to virtually nil since I installed NoSpamNX.

Akismet Stats 2010-12-21

The few spam comments that do end up in the Spam queue are trackback spam (other sites linking to mine in the hopes of getting a reciprocal link back) or human-generated spam. Those are easily taken care of.

If you’re a WordPress blogger and hate dealing with comment spam, I recommend trying out NoSpamNX and see if it helps you!

One More Thing

I noticed an interesting thing about one of these “human-generated” spam comments. The spammer came in from a Google search for the phrase “powered by WordPress”. This phrase shows up in the footer of almost all WordPress blogs as a way of advertising the popular blogging software. No one really reads it – it’s extraneous. But an enterprising spammer decided to use that phrase to find blogs to spam.

So I took the phrase out with simple edit to the footer.php file. No need to help spammers find me! 🙂

Aloha, Nate

Hate comment spam? What do you do to get rid of it? Leave a comment below and share your antispam tips!

10 thoughts on “Defeating Comment Spam Bots”

    1. Sharlene

      This only works on WordPress. Blogspot users have to rely on Google’s in-house spam filtering.

      Yet another reason to get off Blogspot and on to WordPress!

  1. I hate the latest types of spammers, which are those who pretend to comment about a post and then link to their stupid site. I use blogger and require commenters to use the word identifier, so I hate how these spammers somehow bypass that. Or I bet they get paid by the number of comments they leave. Don’t they know I just delete them?

    1. JB,

      I have since removed NospamNX because it was not working as well anymore. I have installed the Growmap AntiSpambot Plugin instead. It’s one extra click for commenters, but at least there’s no CAPTCHA.

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