ssym3tryy
May 14th, 2008, 08:04 PM
Here is an article I wrote a couple of years back. It is a very basic explanation of how proxy servers work. I am sure that most of you already know all this stuff, but I though that it might be helpful to someone out there....
What is a proxy server?
A proxy server is a computer that can be called on to act as a sort of "middle man" between your computer and a specified destination across the network or across the interweb. Basically, it works like this:
In a typical (non-proxy-ed) internet connection your computer requests info directly from the web server that you are trying to access. So, if you type http://www.google.com in your address bar, your computer will send a request to one of google's web servers and then google's server will answer you with the page that you requested. Simple enough.
You ----> Google ----> You
...but, in a Proxy-ed internet connection, your computer sends it's requests to a proxy server, then that proxy server forwards your request to it's destination (in our example, that would be google). The Destination server then sends the page that you requested back to you. (or in the case of a reverse proxy, it would send the requested page to the proxy server and then the proxy would forward it to you)
You ----> Proxy ----> Google ----> You
or
You ----> Google ----> Proxy ----> You
or
You ----> Proxy ----> Google ----> Proxy ----> You
What are proxy servers used for??
Proxy server are used for a number of reasons, including security, content filtering and activity monitoring.
...but that's boring so we won't talk about that. Instead, we will discuss two very cool things that can be done with proxy servers:
Bypass Content Filtering
Does your school or office block you from accessing certain sites? Well that just isn't fair, now is it? You very well may be able to bypass their content filtering methods by directing your traffic through a proxy server.
Here's basically how it work: Their firewall is prohibiting you from initiating a connection with a certain list of restricted sites... but, if you use a proxy server, then to the firewall it only looks like you are initiating connections to the proxy. Therefore, as long as that proxy server isn't on their blocked list, you should be able to bypass their content filtering!
Anonymizing Web Traffic
Certain proxy servers or networks of proxy servers are designed to help anonymize your web traffic.
My favorite example of this is the TOR proxy network. TOR stands for "The Onion Router"
Here is a description of how TOR works: (taken from Wikipedia)
"Users of the Tor network run an onion proxy on their machine. This software connects out to Tor, periodically negotiating a virtual circuit through the Tor network. Tor employs cryptography in a layered manner (hence the onion analogy), ensuring perfect forward secrecy between routers. At the same time, the onion proxy software presents a SOCKS interface to its clients. SOCKS-aware applications may be pointed at Tor, which then multiplexes the traffic through a Tor virtual circuit.
Once inside the Tor network, the traffic is sent from router to router, ultimately reaching an exit node at which point the cleartext packet is available and is forwarded on to its original destination. Viewed from the destination, the traffic appears to originate at the Tor exit node."
Basically, TOR makes it look like you are using the internet or connecting to a network from an IP address that is not your own.
One very cool application of TOR is OperaTOR, (available here: http://archetwist.com/opera/operator) a small program designed to be placed on a thumbdrive that combines the Opera browser and TOR. If you were to insert this thumbdrive into a public computer, like one at the local library, and run OperaTOR you would be able to surf the web anonymously and without leaving a single trace of your traffic on the public computer. Pretty cool, huh??
Another cool use for TOR is to route all your bittorrent tracker requests through it. This will help keep your IP address out of the hands of the evil MPAA/RIAA.
*Important Note* Make sure that you only route your tracker requests through TOR and not all your bittorrent traffic, as that amount of bandwidth would be abusive to the TOR network, not to mention, your downloads would go super slow.
Enjoy!
-SYM3TRY
What is a proxy server?
A proxy server is a computer that can be called on to act as a sort of "middle man" between your computer and a specified destination across the network or across the interweb. Basically, it works like this:
In a typical (non-proxy-ed) internet connection your computer requests info directly from the web server that you are trying to access. So, if you type http://www.google.com in your address bar, your computer will send a request to one of google's web servers and then google's server will answer you with the page that you requested. Simple enough.
You ----> Google ----> You
...but, in a Proxy-ed internet connection, your computer sends it's requests to a proxy server, then that proxy server forwards your request to it's destination (in our example, that would be google). The Destination server then sends the page that you requested back to you. (or in the case of a reverse proxy, it would send the requested page to the proxy server and then the proxy would forward it to you)
You ----> Proxy ----> Google ----> You
or
You ----> Google ----> Proxy ----> You
or
You ----> Proxy ----> Google ----> Proxy ----> You
What are proxy servers used for??
Proxy server are used for a number of reasons, including security, content filtering and activity monitoring.
...but that's boring so we won't talk about that. Instead, we will discuss two very cool things that can be done with proxy servers:
Bypass Content Filtering
Does your school or office block you from accessing certain sites? Well that just isn't fair, now is it? You very well may be able to bypass their content filtering methods by directing your traffic through a proxy server.
Here's basically how it work: Their firewall is prohibiting you from initiating a connection with a certain list of restricted sites... but, if you use a proxy server, then to the firewall it only looks like you are initiating connections to the proxy. Therefore, as long as that proxy server isn't on their blocked list, you should be able to bypass their content filtering!
Anonymizing Web Traffic
Certain proxy servers or networks of proxy servers are designed to help anonymize your web traffic.
My favorite example of this is the TOR proxy network. TOR stands for "The Onion Router"
Here is a description of how TOR works: (taken from Wikipedia)
"Users of the Tor network run an onion proxy on their machine. This software connects out to Tor, periodically negotiating a virtual circuit through the Tor network. Tor employs cryptography in a layered manner (hence the onion analogy), ensuring perfect forward secrecy between routers. At the same time, the onion proxy software presents a SOCKS interface to its clients. SOCKS-aware applications may be pointed at Tor, which then multiplexes the traffic through a Tor virtual circuit.
Once inside the Tor network, the traffic is sent from router to router, ultimately reaching an exit node at which point the cleartext packet is available and is forwarded on to its original destination. Viewed from the destination, the traffic appears to originate at the Tor exit node."
Basically, TOR makes it look like you are using the internet or connecting to a network from an IP address that is not your own.
One very cool application of TOR is OperaTOR, (available here: http://archetwist.com/opera/operator) a small program designed to be placed on a thumbdrive that combines the Opera browser and TOR. If you were to insert this thumbdrive into a public computer, like one at the local library, and run OperaTOR you would be able to surf the web anonymously and without leaving a single trace of your traffic on the public computer. Pretty cool, huh??
Another cool use for TOR is to route all your bittorrent tracker requests through it. This will help keep your IP address out of the hands of the evil MPAA/RIAA.
*Important Note* Make sure that you only route your tracker requests through TOR and not all your bittorrent traffic, as that amount of bandwidth would be abusive to the TOR network, not to mention, your downloads would go super slow.
Enjoy!
-SYM3TRY