Rusty Divine

Live, Love, Learn, Teach

Problem with Authenticated Proxy with PAC file in Windows 8

We had a small problem on our team since we upgraded to Windows 8.1 from Windows 7 last week – only Internet Explorer was working 100% with our proxy server. Other browsers, such as Chrome, would let us get out to most sites, but some sites that were on our active directory group’s allowed list (like github.com) were not working.

The problem kept aggravating us as we found more and more sites and services were broken, but none of which were serious enough to enter a service ticket that would get our network team involved; one of which did look at it briefly and found it worked fine on his machine.

I love how the solution came forward through team effort on the part of Grax and Costenbader and myself: each of us chipped in a few minutes of toying with it throughout the day and did a great job of reporting what we’d found to each other. We even put a bounty of a burger at Honest Abe’s on the line, although in the end we all earned it.

Our proxy server requires authentication and has a PAC file for configuration. Again, these were working great in IE, but not in anything else. I realized we were getting a 407 Proxy Authentication Required error by using LINQPad’s check for update’s tool (chalk another win up for that great tool!).

Grax took the information from the PAC file and was able to manually authenticate using LINQPad’s update tool and got that working. BAM! That was a great break through.

Costenbader then went into Window’s Network Proxy Settings (type that from the start screen to get there) and set Auto Detect Settings to On, but turned off the Auto Configuration Script that was trying to load that PAC file. He then turned on the proxy server and used the information from the PAC file to enter the server and port, and checked the box to not use the proxy for local services.

BAM! That fixed 98% of our problems. I put the finishing touch on when I entered a few of the “except for” addresses into the proxy settings that I grabbed from the PAC file. DONE! We now have access to all the sites we had access to in Windows 7.

So, in summary, the PAC file combined with an authenticated proxy made it appear that Chrome wasn’t working, as well as some other services and tools (we didn’t try FireFox). Chrome uses the computer’s proxy settings though, so by fixing our network proxy settings we fixed Chrome and all the other tools we were trying to use. We aren’t bypassing any restrictions, we’re just changing the way it is configured so that it works on our machines, too!

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