About HTTP Response Pages
As part of access control, you can configure an HTTP response page to display when the system blocks web requests, using either access control rules or the access control policy default action.
The response page displayed depends on how you block the session:
Block Response Page: Overrides the default browser or server page that explains that the connection was denied.
Interactive Block Response Page: Warns users, but also allows them to click a button (or refresh the page) to load the originally requested site. Users may have to refresh after bypassing the response page to load page elements that did not load.
If you do not choose a response page, the system blocks sessions without interaction or explanation.
Limitations to HTTP Response Pages
Response Pages are for Access Control Rules/Default Action Only
The system displays a response page only for unencrypted or decrypted HTTP/HTTPS connections blocked (or interactively blocked) either by access control rules or by the access control policy default action. The system does not display a response page for connections blocked or blacklisted by any other policy or mechanism.
Displaying the Response Page Disables Connection Reset
The system cannot display a response page if the connection is reset (RST packet sent). If you enable response pages, the system prioritizes that configuration. Even if you choose Block with reset or Interactive Block with reset as the rule action, the system displays the response page and does not reset matching web connections. To ensure that blocked web connections reset, you must disable response pages.
Note that all non-web traffic that matches the rule is blocked with reset.
No Response Page for Encrypted Connections
The system does not display a response page if the session is or was encrypted.
No Response Page for "Promoted" Connections
The system does not display a response page when web traffic is blocked as a result of a promoted access control rule (an early-placed blocking rule with only simple network conditions).
No Response Page Before URL Identification
The system does not display a response page when web traffic is blocked before the system identifies the requested URL; see Guidelines and Limitations for URL Filtering.