- The Barracuda Web Filter
- All Firmware Versions
URL shortening services, like TinyURL and Bit.ly, take long URLs like https://www.google.com/search?q=gardening&source=lnms&tbm=isch&sa=X&ei=abPZUvq8DYnOsAS1rYCIDQ&ved=0CAcQ_AUoAQ&biw=1551&bih=917 and transform them into short ones like http://tinyurl.com/k2ha4pu. So how does this affect the web filter's ability to filter such URLs? Could a URL, such as this short one, get around your domain block of Google.com?
The answer is no. When a web browser sends a request to a URL shortening service, the service sends back a URL, which your browser then loads up in the address bar and attempts to access. If the user is allowed to this site, they will be able to get to it. If this request is blocked, the user will receive a block page (or a Page Cannot Be Retrieved error if the page is accessed via HTTPS).
You can test this by creating a URL for a blocked site at one of the URL shortening sites. When you try to use it, you will see the URL Shortening Service request appear in your Web Log first, which will be allowed, followed shortly by the request for the actual page, which will be blocked.
So in a nutshell, URL Shortening services will not allow users to bypass your web filter.
URL Shortening services are generally classified as Content Servers, so if you are blocking those, your users won't be able to use URLs from services such as TinyURL or Bit.ly
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