Can IP anti-spoofing affect the block page?


This article applies to:

  • R3000

Question:

Can IP anti-spoofing affect the block page?

Reply

Question:  Can IP anti-spoofing affect the block page?

When a user goes to a blocked site, the R3000 sends back an HTTP 302 redirect (redirecting the workstation to the block page), while SPOOFING the IP address of the blocked site.  This is meant to trick the workstation into believing that the redirect came from the blocked site.

The workstation then requests the block page from the R3000 (or if you're using a custom block page, from your web server).

If your firewall has IP anti-spoofing enabled, it will likely drop these HTTP 302 redirect packets, and users will not get a block page.  (The redirect packets are sent from the R3000's admin/block page interface, not the listening interface).

Most firewalls will allow you to keep IP anti-spoofing turned on, but ALLOW spoofing from specific servers (e.g. the R3000).

This article was previously published as:
8e6 KB 300314

Last Modified 1/5/2009.
https://support.trustwave.com/kb/KnowledgebaseArticle12646.aspx