Proxy Auto-Configuration URL

One of the easiest ways to change your IP address with a proxy server is by using a proxy auto-configuration URL in your web browser. A  proxy auto-configuration URL tells your browser when to use a proxy server, and what proxy server hostname and port to use.

How does a Proxy Auto-Configuration URL Work?

A proxy auto-configuration URL instructs your web browser to download a javascript  PAC file, normally called proxy.pac, which contains at least one javascript function called FindProxyForURL

Most of the time, this function simply tells your browser to always use a specific proxy server hostname and port for all requests. But the function can also restrict proxy usage based on the request. For example, a proxy server might only support HTTP requests, but not HTTPS requests. 

In that case, the function would examine the request, and if it's for a HTTPS URL, it would tell the browser to skip the proxy and go directly to the site. However, if the request is for a normal HTTP URL, then the proxy would be used. 

ProxyMesh supports both HTTP requests and HTTPS requests, and so the proxy.pac auto-configuration function will work as both a http proxy server and a HTTPS proxy server, but will ignore any non-HTTP requests.

How do I use it with an Authenticated Proxy Server?

Because proxy auto-configuration URLs do not support specifying proxy usernames and password (and for good reason, because it would be a security risk), you must use  IP address authentication

Once your IP is registered with the proxy server, then the proxy auto-config will handle the rest, by specifying the proxy server hostname and port for each request.

How do I set up Automatic Proxy Configuration?

First, you need a proxy auto-config URL to use. ProxyMesh provides all subscribers with this URL in the  account dashboard, which you can find after you signup for ProxyMesh.

Once you have a URL to auto-config the proxy, you must go into your browser's proxy or network settings and look for a setting such as  Automatic proxy configurationAutoconfiguration URLAutomatic proxy configuration URL, or PAC File URL, and then copy/paste the URL.

Once you save this URL in the settings, your browser will be using the automatic proxy configuration for all future requests.

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