June 22, 2010
You may get this message due to:
Network configuration issues related to iPrism
Getting blocked by iPrism when attempting access to an HTTPS site
The screen below was produced when attempting to surf the web after adding a network, but the network wasn't saved properly on exiting Appliance Manager. The solution was to add the network again, save it, verify it was saved, then surf the web again. The problem is reflected by the first bullet (highlighted below) which basically says your machine IP is unknown to iPrism.
Because of encryption, Proxy mode will indicate a blocked HTTPS site with a page similar to the following:
The URL port number 443 indicates HTTPS traffic
The remaining messaging seems to indicate DNS name resolution issues, but it is a blocked HTTPS page. You can easily reproduce this issue by changing the rating for an HTTPS site so that it is blocked. For example, financial sites use HTTPS.
Note that users can be blocked by design according to their profile as assigned by username, but they can also be blocked (perhaps inadvertently) by network profiling, should they fail to establish an authenticated web session prior to visiting https sites. This is easily remedied, see:
How do I Establish an Authenticated Web Session for HTTPS?
If you are using Internet Explorer 8, transparent (bridge) mode will indicate a blocked HTTPS site with a page similar to the following: