how to Block Website on ASA ?

Unanswered Question
sachinga.hcl Fri, 09/10/2010 - 05:21
User Badges:
  • Silver, 250 points or more

Hi Vinayak,

Can you get away with Blacklisting/whitelisting just the IP addresses and/or websites that your users need to visit?  If so, you can probably use just your ASA.  Otherwise you're going to want a good web filtering/proxy solution.  Check out IronPort, Webwasher, Blue Coat, SurfControl, or even Squid (open source.)

Otherwise can also tie the ASA directly into a filtering product like WebSense, check out the ASA documentation.

When deploying a web filtering product you can either go "inline" or transparent by using WCCP redirection, but I'd suggest against it, since it breaks normal web browser behavior.  Better option is to use WPAD (web proxy auto-detect) and have your browsers point-to and/or be explicitly configured to use the proxy.

You can use combination of regex & HTTP inspection with ASA 7.2+ code to achieve this

regex YOUTUBE "youtube\.com"

policy-map type inspect http xyz


  protocol-violation action drop-connection log

match request header host regex YOUTUBE

  drop-connection log

policy-map global_policy

class inspection_default



< SNIP..>



  inspect http xyz

Another example at
Block Certain Websites (URLs) Using Regular Expressions with MPF Configuration Examples (useful in your case for blocking sites specifically)

A good example can be found at
ASA and PIX using http inspection to filter URLs and Hosts in HTTP

Please keep in touch if you face any issues in this regard and do let me know so that i can troubleshoot it further for you .

Please rate  if you find it informative.


Sachin Garg


This Discussion