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What Is Web Proxies

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This is my effort to share my experiment and notes about web proxies with you.
Simply defined, proxies/servers are the application (or dedicated server) that enables the indirect connection between a client and a resource on a remote location. Initially, proxies were invented to provide many functions such as server load balancer, fast delivery of contains to support a distributed system but later more functionality such as encryption, traffic filtering, redirection, URL rewrite and deep packet inspection was added.

Type of proxies
Although there are many type of proxies such as Web proxy, FTP, SOCKs and more, in this document is focused on Web proxy.

Web Proxy
The most popular proxies over the internet are Web proxies those were built …show more content…

o All other traffic that is initiated by another source, such as curl, wget, API's, ftp clients or from a different browser (without explicit proxy), will be forward to machines default gateway.
• How to configure explicit proxy? o Direct configuration:
 One can manually set a browser's network setting for proxy by providing the Destination IP(DIP) and Destination Port(DPort) and supported protocols.
 In this case all traffic is forwarded to the proxy; however, there is another way in where traffic is forward to proxy based on requested URL. o Proxy Auto Configuration (PAC file) and its location in network in form of URL:
• A PAC file is a text file of functions and the URLs to reroute the traffic based on URLs. For example, in an enterprise setting, a PAC file can define the rules such as if the URL (or end-point) is an external address then next hop is another proxy and if end-point is internal address then send it directly to the destination.
• A PAC file resides on a server, and a browser will access the PAC file using a given URL.
• The PAC file should be on the root of the severing server
• For configuration, select browser-> network settings-> auto configuration-> use auto configuration script-> and give location “ Error! Hyperlink reference not valid. address of server:port/proxy.pac”
• A PAC file may looks as following: function FindProxyForURL(url, host)
{ if (!shExpMatch(url,

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