Dealing with spam by blocking URLs?

Question

I run a giant community. Many spammers will use link shorteners or .tk domains that 301 to their spam offer. How are sites detecting the final domain and is this a viable solution to block spam?

ex. I'll just block the spam: bit.ly/xdfd but then they will just use a different shortened link.

Answer 1

There is plenty solutions to expand short url:

• What is the best way in PHP or JS to expand shortened URLs like Bitly, Tinyurl to find the original URL?
• ExpandUrl (a java solution)
• Expand short URL – Simple PHP app for beginners
• expanding short url to original url using PHP and CURL
• Simple-URL-Expander (a javascript solution)

When user submit a new post, you can apply a function that expand url for all url inside the post. Then you will have the real url. So you can appy what ever spam solution you use to reject / accept the post.

You can also replace the shorten url by the full one to avoid short link on your commutiy board.

Answer 2

Many forums simply forbid all url shorteners. There is no simple solution to that, you may try also specific solutions for your platform (phpBB, vBulletin, etc.)