spinsurf.net
The place to be
free proxy list 8080
free proxy list 8080
Proxy auto-config
From Wikipedia, the free encyclopedia Jump to: navigation, searchA proxy auto-config (PAC) file defines how web browsers and other user agents can automatically choose the appropriate proxy server (access method) for fetching a given URL.
A PAC file contains a JavaScript function "FindProxyForURL(url, host)". This function returns a string with one or more access method specifications. These specifications cause the user agent to use a particular proxy server or to connect directly.
Multiple specifications provide a fallback when a proxy fails to respond. The browser fetches this PAC file before retrieving other pages. The URL of the PAC file is either configured manually or determined automatically by the Web Proxy Autodiscovery Protocol.
Contents
|
Context
Modern web browsers implement several levels of automation; users can choose the level that is appropriate to their needs. The following methods are commonly implemented:
- Manual proxy selection: Specify a hostname and a port number to be used for all URLs. Most browsers allow you to specify a list of domains (such as localhost) that will bypass this proxy.
- Proxy auto-configuration (PAC): Specify the URL for a PAC file with a JavaScript function that determines the appropriate proxy for each URL. This method is more suitable for laptop users who need several different proxy configurations, or complex corporate setups with many different proxies.
- Web Proxy Autodiscovery Protocol (WPAD): Let the browser guess the location of the PAC file through DHCP and DNS lookups.
Proxy Configuration
Your computer operating system (ie Windows, Mac, Linux, etc) has certain settings needed to communicate over the web, usually obtained from your Internet Service Provider. Either anonymous (proxy to use a proxy server) or real settings may be used to make your network connections. For more information, read Windows Proxy Connection or contact your own ISP or search for your own OS proxy requirements.
The PAC file
The Proxy auto-config file format was originally designed by Netscape in 1996 for the Netscape Navigator 2.0 and is a text file that defines at least one JavaScript function, FindProxyForURL(url, host), with two arguments: url is the URL of the object and host is the hostname derived from that URL. By convention, the PAC file is normally named proxy.pac. The WPAD standard uses wpad.dat.
To use it, a PAC file is published to a web server, and client user agents are instructed to use it, either by entering the URL in the proxy connection settings of the browser or through the use of the WPAD protocol.
Even though most clients will process the script regardless of the MIME type returned in the HTTP request, for the sake of completeness and to maximize compatibility, the web server should be configured to declare the MIME type of this file to be either application/x-ns-proxy-autoconfig or application/x-javascript-config.
There is little evidence to favor the use of one MIME type over the other. It would be, however, reasonable to assume that application/x-ns-proxy-autoconfig will be supported in more clients than application/x-javascript-config as it was defined in the original Netscape specification, the latter type coming into use more recently.
A very simple example of a PAC file is:
function FindProxyForURL(url, host) { return "PROXY proxy.example.com:8080; DIRECT"; }
This function instructs the browser to retrieve all pages through the proxy on port 8080 of the server proxy.example.com. Should this proxy fail to respond, the browser contacts the website directly, without using a proxy. The latter may fail if firewalls or other intermediary network devices reject requests from sources other than the proxy, a common configuration in corporate networks.
A more complicated example demonstrates some available JavaScript functions to be used in the FindProxyForURL function:
function FindProxyForURL(url, host) { // our local URLs from the domains below example.com don't need a proxy: if (shExpMatch(host, "*.example.com")) { return "DIRECT"; } // URLs within this network are accessed through // port 8080 on fastproxy.example.com: if (isInNet(
Nothing was found!
Even more about free proxy list 8080
Media
Network