Status: 12209 Forefront TMG requires authorization to meet the request. The technet article I discovered the online proxy filter work round, says : The drawback of this workaround is that outbound HTTP requests from SecureNAT and Firewall clients will then go directly to the Web server instead of being redirected to the Web Proxy filter.
Once a connection to the net proxy listener has been established, in packet eight the client sends an HTTP GET request for In packet thirteen you will see that the Forefront TMG firewall denied the request and replied with an HTTP 407 response, indicating that proxy authentication was required.
The HTTP Filter in Forefront TMG can also be capable to filter HTTPS traffic utilized in reverse internet server publishing situations the place HTTPS Bridging is used and for outgoing HTTPS requests when the HTTPS inspection characteristic of Forefront TMG is activated.
If only Internet Explorer access is required from the ISA Server computer, the preferred workaround for this problem is to enable Web Proxy entry on the Local Host community, and set the Internet Explorer browser Web Proxy settings on the ISA Server laptop to make use of Local Host port 8080 as a proxy.
Some examples for these purposes are Outlook Anywhere, the Remote Desktop Gateway service and applications like Skype, Windows Live Messenger and lots of more which encapsulates their native protocols into the HTTP/HTTPS protocol, which permits the traffic to bypass the Firewall.