The PhoneBoy Blog

FireWall-1 FAQ: Blocking HTTP Downloads

Last Modified: 01 Jan 2004

Please note: This content was from when I was operating my FireWall-1 FAQ site, which I stopped operating in August 2005. For some reason people still have links to this stuff on the Internet that people are still clicking on.

I am making this information available again AS IS. Given how old this information is, it is likely wildly inaccurate. I have no plans to update this information.

If you're still running versions of Check Point VPN-1/FireWall-1 where this information is still relevant to you, do yourself a favor and upgrade to a more recent release. If you happen to be running a current release and the information is useful, it's by happenstance :)

There is no utterly fool-proof way to filter HTTP downloads. MIME-types are generally the most effective, but require a CVP server for proper implementation. You can filter based on extension, but you might also catch legitimate page queries that use .exe in the URL. People can also use different extensions for files, which can get around these restrictions.

If you want to try this anyway, create a resource. The URI Definition window would have the following in the “Match” tab:

Schemes: HTTP
Methods: GET
Host:    *
Path:    {*/*.{exe,zip,bin},*.{exe,zip,bin}}
Query:   *

Note that I’ve inclded exe, zip, and bin extensions. You can add your own as you see fit.

You would then create a rule that uses this resource (which I’ve called downloads below) and denies access to anything matching this resource (note this rule should show up before your rules that allow general HTTP access):

If you want to restrict access by user group, the rules look like:

Once a packet could potentially match a user auth rule, the packet is then allowed by the “least restrictive” rule. It is therefore important that the “allowed user atuh” rule appears before the deny access rule.