All Bakwaas!

What is a proxy ?

A proxy is a computer (a personnal computer or a server) that is hosting a program, a proxy server software. This one can relay your connections to a remote server (web, irc, email, ...), as a result the remote server will see the proxy server ip rather than yours.

Depending on the kind of computer, kind of bandwith availlable, the software installed (the proxy server), and the time when you're using it, the proxy will be good or not.

The proxy server can be a web server (IIS, Apache, ...) badly setted up, a virus installed unvoluntarily on a computer, or an open proxy software dedicated to spy proxy users. Or.. It could be so many things in fact !

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Socks, http, connect, ...

There's two major kinds of proxies : HTTP and SOCKS

The difference between socks and http is the protocol, the 'language' you'll have to use to communicate with the proxy.

Each one has several versions : sock 4, sock 4a, sock 5, http 1.0, http 1.1... The protocol will remain the same, but wih small differences.

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SOCKS
When you're using a sock proxy with a software (web browser, irc client, ..) your software asks to the socks proxy server to establish a connection with the remote host, and then everything you'll send will be forwared to the remote host, and everything the remote host will send will be forwarded to you. The proxy server is a tunnel, a gateway between you and the remote host.

It (should) never 'analyse' or modify datas that is passing through, that's why a socks proxy is always be anonymous (or should be).


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HTTP protocol

When a proxy supports http protocol, that's (in most cases) because it is a webserver. That's why generaly an http proxy will work longer than a sock one. There's rarely web servers on dynamic ips !!

Ok, two methods to use an http proxy.

The first one has excalty the same behavior as a socks proxy : you establish a tunnel and then communicate like if you were directly connected to the remote host. This method is called "HTTP Tunneling". The web server have to support the CONNECT method.

HTTP Tunneling is used, in exemple, to connect proxies on IRC servers. Note that web browsers never implement this method.

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The other method is protocol-oriented, it can only work for web browsing.
When you're requesting a page (let's say a google search), your web browser first makes a connection on www.google.com port 80, and then sends his request "give me the page /search?q=toto".

When you're using an http proxy server, your web browser will connect on it and send almost the same request, but with the complete remote host : "give me the page http://www.google.com/search?q=toto". Then the proxy server will connect to google.com and forward your request.

BUT. Because the proxy server "understands" what is passing through, it can add informations into the requests (your IP, informations about its cache, the gateway ip, ...). That is what proxy judges are analysing to determine the proxy level.

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And few things to know

Of course, the proxy servers are not there for our pleasure :) Most often, they have rules to restrict their usage to ip ranges, or ports.

That is, in part, why a proxy can work for you but not for somebody else. You won't use it on the same remote host or remote port. Also remember that the remote host can block the proxy server ip with a firewall.

"Gateways" are proxies that receive your requests from an IP but forward them to the remote host with another IP. Both socks and http can be gateways, but it won't affect your anonymity.

Codeen/Planetlab proxies accept both sock 4 and http protocols, but for webbrowsing only. They are anonymous (level 3) and gateways, but you they can't be used for automated tasks.
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Thanks and Regards;
s.-.a.-.n.-.j.-.a.



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