[Pac File Bypass Proxy For Local Addresses By Name
Amabella Tevebaugh
The retired, out-of-support Internet Explorer 11 desktop application has been permanently disabled through a Microsoft Edge update on certain versions of Windows 10. For more information, see Internet Explorer 11 desktop app retirement FAQ.
To bypass the proxy, select the Bypass proxy server for local (intranet) addresses check box in the Local Area Network (LAN) Settings dialog box. This method bypasses the proxy for all addresses that don't contain a period (for example, ). These addresses will also be resolved directly.
In earlier versions of the Windows operating system, Internet Explorer Maintenance (IEM) is used to configure Internet Explorer settings by using Group Policy. In Windows 8, the IEM settings have been deprecated in favor of Group Policy Preferences, Administrative Templates (.admx), and the Internet Explorer Administration Kit 10 (IEAK 10).
If a protocol is specified, requests that use the address will be bypassed only if they are of the indicated protocol type. Address entries are case insensitive, the same as they are for the protocol type.
Enter a wildcard at the beginning of an Internet address, IP address, or domain name that has a common ending. For example, use *.example.com to bypass any entries that end in .example.com, such as some.example.com and www.example.com.
Enter a wildcard in the middle of an Internet address, IP address, or domain name that has a common beginning and ending. For example, the entry www.*.com matches any entry that starts as www and ends as com.
Enter a wildcard at the end of an Internet address, IP address, or domain name that has a common beginning. For example, use www.microsoft.* to bypass any entries that begin as www.microsoft., such as www.microsoft.com, www.microsoft.org, but not www.microsoftcorporation.com.
The list is intended to bypass servers, and not URLs. Therefore don't enter subwebs or trailing slashes, such as -us or www.microsoft.com/, as they are invalidating the whole list otherwise.
If you bypass the proxy for a local domain, use *.domain.com. This method doesn't use the proxy for any computer name that ends in .domain.com. You can use the wildcard for any part of the name. For more information, see The Intranet Zone.
This PAC always returns the proxy proxyserver:portnumber. For more information about how to write a PAC file and the different functions of a PAC file, see Introduction of FindProxyForURL.
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.
When you connect to a Web server using the Internet Protocol (IP) address or Fully Qualified Domain Name (FQDN) on the local network, Microsoft Internet Explorer or Windows Internet Explorer connects through an assigned proxy server even if the Bypass proxy server for local addresses option is turned on.
However, if you connect to a Web server using the host name (for example, ) instead of the IP address (for example, ) or FQDN (for example, ), the proxy server is bypassed and Internet Explorer connects directly to the server.
I've got a machine here that's running a website. It's only really a development machine but it has IIS on it for testing purposes. Problem is that when pages get loaded in internet explorer using the machines name, the request is going out to the proxy server which is coming back with an error:
The error makes sense as the machine is really seed-dev1.net.dcs.hull.ac.uk. Regardless, I don't want it to be going off to the proxy server for local addresses. Not only is 'Bypass proxy server for local addresses' ticked on the proxy settings, but I've added exceptions in addition so it shouldn't be using the proxy for addresses beginning with: '*.hull.ac.uk; localhost; 127.0.0.1; seed-dev1' I can confirm that the exceptions are at least working because I can get to any pages within hull.ac.uk which I wouldn't be able to if I hadn't put it in the exception list.
A quick restart and it still doesn't work. Any pages that I try to access using the machine name just get that bad page returned from the proxy. Using localhost is all well and good for a single page but then you click on a link and it just switches back to the machine name in the url.
Check your IE Zones - I've seen it happen at times that IE would place a local server in the Internet zone, thus causing it to ignore the "bypass proxy" setting. Haven't figured out the reason why yet, but it does appear related to either a non-standard port or the server not being a member of the same Windows Domain as the client. To be honest, this is not something I've spent too much time researching; once I found a solution I moved on.
When you connect to a Web server using the Internet Protocol (IP) address or Fully Qualified Domain Name (FQDN) on the local network, Microsoft Internet Explorer or Windows Internet Explorer connects through an assigned proxy server even if the Bypass proxy server for local addresses option is turned on.
In the early days of IE, a local server was defined to be "a server without periods in the name". in your example " -dev1/" would be local and " -dev1.hull.ac.uk:5555/" would be remote and sent to the proxy server.
In the IE Internet Options dialog, click on the Advanced button next to the port number text box for the proxy setting. You should see a text box at the bottom of this new dialog box that allows for exceptions. Try entering seed-dev1.hull.ac.uk in that box and clicking the OK buttons until you get back to the main IE window.
This will happen if your proxy exception list is injected manually through the registry and is missing a ; semicolon after the last value. The reason is that the registry stores the checkbox at the end of the registry exception string as and this is never properly parsed if the last semicolon is missing.
Other symptoms that may occur are... websites like may incorrect get a .com suffix appended or display 404 Page not Found (depending on the proxy software). Some pages and redirects will stop functioning and you may even find yourself un-clicking "Enable Protected Mode", but it's not that... it's the semicolon.
If this started happening in 2018, it may be triggered by a Windows update, although it's impossible to know without the source code or consulting Microsoft. Here's the Windows update text from July 2018 that reads as a possible culprit...
However, I could not understand why is this happening. AFAIK, when you request to access to an address, domain name translation must take place, whether or not you have requested a local address or an internet address.
It's a routing problem (to state it in a simple manner). When you configure a proxy server, you're instructing your browser to send all the web connections to a unique ip (the proxy). The proxy server receives the connection request but if it's addressed to a private IP (internal address) it will fail.As you say, the options are adding an exception (you can use wildcards, like 10.* or *.your.domain).
I had the same question. Using my MacBook Air (13-inch, Early 2014) macOS Sierra, the wi-fi keeps going off, I am trying to figure out why. I created a new location under my Network designated by my ISP. When I go to Network>Open Network Preferences>Assist Me>Diagnostics>
Thank you, IDK if I understand. ? So, Is it okay to "bypass" that setting? Why do I want to bypass it under proxy settings on my network? Please advise. Aloha from me < really truly technically challenged.
The original purpose of a Proxy was so corporate networks could put up a firewall to keep the outside world out and to limit what traffic employees could send to the outside world (generally web connections, but some companies configure their firewall to allow some additional traffic).
Anyway, systems inside the company generally need to access lots of other systems inside the company, including internal web services. If ALL traffic was sent to the firewall, employees would never be able to access anything inside the company.
Moving back to your home. Most users at home, just have a simple Local Area Network (LAN), and it is possible they want to access devices in their home, even if they have a Proxy setup for their network access. This would be the .local domain. So excluding .local should allow any app that would use the proxy server to also know that if the connection is local, they should just make a direct connection, and not try to go through the proxy server.
But there are some services that will use a proxy server to make your web surfing look like it coming from some other location. Or a proxy server has been setup to filter all the web traffic going to from the computer.
Now if you tell me you are remotely connecting to your company over a VPN connection, and having a Proxy server configured is the only way to also surf the web while connected to your company, then that would explain the use of a proxy. AND if you are using a VPN, there is a good change the VPN will not allow you to talk to anything on your home network (which is a real pain when you want to print something on a home network printer; but I digress). Anyway, if you are using a VPN it may not matter whether your proxy setting bypass .local or not, as the VPN often times sends ALL traffic to the VPN server.
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