When you set the IFP response to Send error message as a redirect, it will always use the first defined proxy port on the list.
If you have a block action as a response to an IFP request, then the redirect URL will always be:
However, you do not have to use a Block Action. If you want it to redirect to a custom page, you can use a Redirect Action, and set the Redirect.URL:
IFP [✔] Enabled [✘] Disabled in Cloud
Applies to: [✔] Requests [✔] Responses [✘] Embedded Objects
1: Connection.Protocol equals "IFP"
Enabled Rule Action Events Comments [✔] Enabled Block
1: URL.Categories<URL Filter: Default> at least one in list URL Filter: Default Blocked Categories
Redirect<Default> Set Redirect.URL = "http://block.mwginternal.com/block.html" [✔] Enabled Stop
Then the destination web server displays the block page.
You can have MWG as the destination web server, and you can embed parameters into the block page URL and have the web server parse them and display them back on the block page.
If you use Send error message in IFP, then you can have very small pieces of HTML returned to the client, but there is a size limit of 1024 bytes. can't display much with HTML that small.