FortiOS 7.4.4 Web Filter didnt show replacment message (Blocked Page)

[itmdadmin]

I have a foritgate 600E with fortios 7.4.4 used as a proxy, and I created a new proxy policy with web filter security porfile to blocked the webmail and instant message websites. It block the websites with the broswer's block message instead of the replacemnt message (Blocked Page) of the FortiOS for all https website.

Below is the case i have try:

1.  Web Filter Profile (Flow-Base) + SSL Certificate Inspeaction

2.  Web Filter Profile (Flow-Base) + Full SSL Inspeaction

3.  Web Filter Profile (Proxy-Base) + SSL Certificate Inspeaction

4.  Web Filter Profile (Proxy-Base) + Full SSL Inspeaction

 the CA cert of foritnet is installed in my computer and the replacement message of Application Control is wokring fine.

[ametkola]

Hello,

In this case FortiGate acts as web server and uses the Fortinet default certificate signed by Fortinet CA.To view that replacement message, you need to install the certificate on the host machine , clear the cache and test in different browsers to check the issue. 

Kind regards,

[itmdadmin]

 the CA cert of foritnet is installed in my computer and the replacement message of Application Control is wokring fine but it just not working with web filter

[nathan_h]

You can try to disable the blocking on the browser. It might be the browser already blocked it and the request didn't reach the Fortigate

[itmdadmin]

No blocking is enabled and i had also tested in 3 different broswer ( Edge , Chrome and Firefox)  which return with same result 

[ametkola]

Hello,

When SSL deep inspection is enabled, a replacement message will appear depending on the protocol. For example, with HTTP2, the blocking is done in the SSL key exchange once
the first server packet is delivered and replacement messages can not be displayed.So replacement message for https based applications may not be displayed for all at the same time
FortiGate application control can block the traffic by resetting connection.

Can you please try for the HTTP traffic and check the behaviour ?

Kind regards,

[itmdadmin]

HTTP website can show the replacement message