Alex Mills

When it comes to spam and <a href="https://codex.wordpress.org/Introduction_to_Blogging#Pingbacks" rel="nofollow ugc">pingbacks</a>/<a href="https://codex.wordpress.org/Introduction_to_Blogging#Trackbacks" rel="nofollow ugc">trackbacks</a>, the vast majority by far is via trackbacks rather than pingbacks. Very, very few people use trackbacks for legitimate uses anymore (I’ve gotten less than 5 in the last 8 months) as WordPress, etc. all use pingbacks now as their primary ping method.
I had already installed <a href="http://ocaoimh.ie/cookies-for-comments/" rel="nofollow ugc">Cookies For Comments</a> which successfully stops most spam comments but I still had to deal with the tons of trackback spam. So, I wrote this plugin.
It will disable new trackbacks across your site, both legitimate and spam. However since very few people use trackbacks legitimately, this combined with Cookies For Comments should cut your spam down to next to zero.
Why should I use this plugin over one of those trackback validator plugins?
Most non-Akismet style anti-trackback spam plugins work by connecting to the URL that sent the trackback and looking for a link to your blog. The problem with this is that many spammers actually post links to your blog in their spam posts rendering those types of plugins useless. Even those that check the IP address to make sure it matches are beaten by spam blogs (aka splogs).
In the end it’s up to you what to use for anti-spam, but I personally use Cookies For Comments, this plugin, and then Akismet to catch anything that makes it through.

Disable Trackbacks

Globally disables trackbacks to cut down on spam. Very, very few people legitimately use trackbacks and spammers love them, so it's worthy tradeo …

baptiste.gourdin

TalkBack is a open-source secure LinkBack mechanism based on a public-key cryptography that aims at tackling the blog spam problem at its root: instead of detecting spam via the content analysis like Akismet, TalkBack prevents spammers from posting LinkBack notifications. When installed TalkbBack add the two following lines of defense to your blog:
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The first line of defense is a lightweight PKI (Public Key Infrastructure) that ensures the identity of blogs by using public key cryptography. Moreover using cryptography allows TalkBack to guarantee that no one can tampers with your TalkBack notifications and that the receiver will received them unaltered.
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The second line of defense, is a global rate limiting system enforced by the TalkBack authorities that ensures that with a single blog identity, a spammer cannot massively spam TalkBack aware blogs.
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TalkBack is compatible with every other defense mechanism and do not store/disclose any private information about your blog or you. As a matter of fact if you don’t trust the network, TalkBack can also encrypt your notification to protect them from eavesdroppers.
A complete description of Talkback is available here: http://code.google.com/p/talkback-client/downloads/detail?name=talkback-paper.pdf and the source code here: http://code.google.com/p/talkback-client/downloads/detail?name=talkback-wordpress-plugin.pdf

Talkback

TalkBack is a secure protocol for LinkBack notification designed to prevent the blogosphere from being spammed.

Disable Trackbacks vs Talkback