Tobiask

Simple Trackback Validation Plugin performs a simple but very effective test on all incoming trackbacks in order to stop trackback spam. Now with topsy.com blocker.
How it works:
When a trackback is received, this plugin
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checks for topsy.com trackbacks and marks this as spam.
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checks if the IP address of the trackback sender is equal to the IP address of the webserver the trackback URL is referring to. This reveals almost every spam trackback (more than 99%) since spammers do usually use bots which are not running on the machine of their customers.
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retrieves the web page located at the URL included in the trackback. If the page doesn’t a link to your blog, the trackback is considered to be spam. Since most trackback spammers do not set up custom web pages linking to the blogs they attack, this simple test will quickly reveal illegitimate trackbacks. Also, bloggers can be stopped abusing trackback by sending trackbacks with their blog software or webservices without having a link to the post.
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There are several options available and you also can enable logging to get all actions, which are performed by the plugin, logged. Also, you can select how to treat spam trackbacks (do not save in the database or mark as spam or place into moderation) and several other stuff.
Please visit <a href="http://sjmp.de/blogging/simple-trackback-validation-with-topsy-blocker/" title="Simple Trackback Validation with Topsy Blocker" rel="nofollow ugc">the official website</a> for further details and the latest information on this plugin.

Simple Trackback Validation with Topsy Blocker

REPLACEMENT of the original Simple Trackback Validation Plugin from Miachel. Performs a simple but very effective test on all incoming trackbacks in o …

kingjeffrey

From the authors of <a href="https://wordpress.org/extend/plugins/wp-typography/" rel="ugc">wp-Typography</a> comes wp-TrackbackPopup.
In WordPress the default trackback link behavior causes persistent user confusion. Knowledgeable users right-click on the link and copy the link location. But the vast majority of users click the link — expecting to copy the link from the browser’s location bar — only to be redirected back to the very page they were on. The standard implementation does not provide the expected result.
wp-​​TrackbackPopup resolves this issue. It uses unob­tru­sive JavaScript to create a popup win­dow when a user clicks the track­back link. The popup window pro­vides a text ver­sion of the track­back URL for easy copy­ing and pasting. 
The popup window may be styled to match your existing theme.
View the <a href="http://kingdesk.com/projects/wp-trackbackpopup/" title="wp-TrackbackPopup Homepage" rel="nofollow ugc">wp-TrackbackPopup homepage</a> for more information.

wp-TrackbackPopup

The standard WordPress trackback link behavior does not provide users their expected result. wp-TrackbackPopup resolves this issue.

Simple Trackback Validation with Topsy Blocker vs wp-TrackbackPopup