This one is once again from one of the cases I worked on recently. Users were trying to access UAG portal and while trying to do that they were getting error

"http error 403.6 -forbidden the ip address from which you are browsing is not permitted to access the requested web site"

Troubleshooting Approach and Resolution

In order to verify if this portal is accessible from the UAG server itself , we logged on UAG server and open IIS management and tried to browse this portal from the UAG machine itself. We got following when we tried to access it.

and that was what we were getting on the Users machine while they tried to access UAG portal.

The Error was pointing to the IP address not permitted access. This directed us to look at the IP and domain restrictions on the websites hosted on IIS as shown below.

In the IP address and Domains restrictions of default website as expanded and shown below there is a setting "edit feature setting"

we checked that setting and found that it was denying access to unspecified clients as shown below

We changed it to allow and ran command iisreset in the command prompt.

After this we tested the access and we were able to access the UAG portal .