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Hello everyone my name is vijay kumar Devireddy and i am glad to have you back on my episode 58 today we're going to discuss Proxy Servers.A proxy server is a device that acts as a middle man for your clients.For example, if you're at work and you wanted to connect to ,your work computer's likely going to go from itself, to a proxy server within your company's LAN.And then, that proxy server makes the connection to Dion Training to get the information that you requested.And then it will hand it back to you.This middle man approach allows the company to log everything that's being requested,who made them, and to filter out things they don't want you to access.There are four types of proxies in use today.IP Proxy, Caching Proxy, Content Filter,and Web Security Gateways.An IP Proxy is used to secure a network by keeping machines behind it anonymous.When your work computer decides to connect to through the proxy in my example above,my server doesn't know which particular computer is actually connected to it from your company's network.All I see is the proxy server itself.This is because your proxy is using NAT to translate your request from your machine into a request from the proxy.If you had 20 different computers on there tryin' to access my web server,it would still just look like one machine to my server, not 20.The next type is called a Caching Proxy.Caching Proxies are used to attempt to serve client requests without actually connecting to the remote server each time.Let's say that you went to my website at diontraining.com,and then your coworker,five minutes later, tried to go to diontraining.com,just like you did.Well, the proxy, if it's using a cache,is going to be able to keep a copy of my webpage from the first time it fulfilled your request.Then, when your coworker requested it,it would simply give it from its cache instead of going and getting a new copy from my site.This will allow your company to save on bandwidth costs,and increase the speed of delivery for your coworker, because it already has it locally,inside your network.The most common caching proxy is known as an HTTP Proxy,which attempts to cache the web pages that are visited by users, such as the example I just gave you.Caching proxies are not as effective as they used to be, though,because we all live in a Web 2.0 world with lots of customized content being served up to us.So, for example, if you went to Facebook.com and your coworker went to Facebook.com,both of your Facebook feeds look drastically different, don't they?This is because you each get different information based on your friends and your likes and your desires.So caching here isn't very helpful because of this Web 2.0 structure.Also, most caching proxies only keep a copy of the information they get for about 24 hours.And after 24 hours, they're going to go back out and request a new copy to ensure that they get the latest information.Now, to simplify the installation and configuration of a caching proxy in your web browser,there's a special type of file called a PAC, a Proxy Auto-Configuration file.This file contains the settings needed for a host to connect to the proxy server.Unfortunately though,these files are subject to modification, and could be used to redirect the user to an attacker's control proxy instead of your organization's.For this reason, it is better to disable the PAC files, and manually configure your proxy settings on your host machines, or you can push these out using a global policy object, or GPO update.Now, the third type of proxy is called an Internet Content Filter.These are used in large organizations as a way to prevent users from getting to stuff that they don't want you to access at work..