Proxy server
Web Hosting Tutorials 2 Comments »A proxy server Share one internet connection with ALL the computers on your local network or it is a computer that offers a computer network service to allow clients to make indirect network connections to other network services. So basic work is like Proxy (proxy server) is a server that acts as mediator between the client (the computer of a user) and server (the computer on the other ends of network connection on which the information requested by the user appears for example web server site.) When clients request data from an Internet resource,traffic goes from your web browser/application first through the proxy before it reaches the requested sources and back through the proxy then the proxy will transmit the data to you.
Proxy server that sits between a client application, such as a Web browser, and a real server. It intercepts all requests to the real server to see if it can fulfill the requests itself. If not, it forwards the request to the real server.
Do not confuse a proxy server with a NAT (Network Address Translation). Although they appear to be very similar, a proxy server actually does the work of connecting to, responding to, and receiving traffic from the Internet. In other words, it acts on behalf of the client computer. A NAT, on the other hand, merely changes the origination address of traffic coming through it and passes it to the Internet. The computer behind the NAT,not the NAT itself, does the work. The NAT is intended to be transparent to the whole process.
For those who understand the OSI (Open System Interconnection) model of networking,the technical difference between a proxy and a NAT is that the proxy server works on the transport layer (layer 4), or higher of the OSI model, whereas a NAT works on the network layer (layer 3).
How Proxy Servers Work :
1. When a computer on the intranet makes a request out to the Internet-such as to retrieve a Web page from a Web server-the internal computer actually contacts the proxy server, which in turn contacts the Internet server. The Internet server sends the Web page to the proxy server, which then forwards the page to the computer on the intranet.
2. Proxy servers log all traffic between the Internet and the intranet. For example, a Telnet proxy server could track every single keystroke hit in every Telnet session on the intranet-and could also track how the external server on the Internet reacts to those keystrokes. Proxy servers can log every IP address, date and time of access, URL, number of bytes downloaded, and so on. This information can be used to analyze any attacks launched against the network. It can also help intranet administrators build better access and services for employees.
3. Some proxy servers must work with special proxy clients. A more popular approach is to use off-the-shelf clients such as Netscape with proxy servers. When such an off-the-shelf package is used, it must be specially configured to work with proxy servers from a configuration menu. Then the intranet employee uses the client software as usual. The client software knows to go out to a proxy server to get the data, instead of to the Internet.
4. Proxy servers can do more than relay requests back and forth between an intranet and the Internet. They can also implement security schemes. For example, an FTP proxy server could be set up to allow files to be sent from the Internet to a computer on the intranet,but to block files from being sent from the corporate network out to the Internet-or vice versa. In this way, intranet administrators can block anyone outside the corporation from downloading vital corporate data. Or they can stop intranet users from downloading files which may contain viruses.
5. Proxy servers can also be used to speed up the performance of some Internet services by caching data-keeping copies of the requested data. For example, a Web proxy server could cache many Web pages, so that whenever someone from the intranet wanted to get one of those Web pages, they could get it directly from the proxy server across high-speed intranet lines,instead of having to go out across the Internet and get the page at a lower speed from Internet lines.
The different types of Proxy Servers :
There are many different types of Proxy Servers out there. Depending on the purpose you can get Proxy Servers to route any of these common protocols, and many more ;
1)FTP Proxy Server:
Relays and caches FTP Traffic.
2)HTTP Proxy Server:
A one way request to retrieve Web Pages.
3)Socks Proxy Server:
A newer protocol to allow relaying of far more different types of data, whether TCP or UDP.
4)NAT Proxy Server:
This one works a little different, it allows the redirection of all packets without a Program having to support a Proxy Server.
5)SSL Proxy Server:
An extension was created to the HTTP Proxy Server which allows relaying of TCP data similar to a Socks Proxy Server. This one done mainly to allow encryption of Web Page
requests.
Furthermore, a Proxy Server can be split into another two Categories:
1)Anonymous:
An Anonymous Proxy Server blocks the remote Computer from knowing the identity of the
Computer using the Proxy Server to make requests.
2)Transparent:
A Transparent Proxy Server tells the remote Computer the IP Address of your Computer.
This provides no privacy.
Anonymous Proxy Servers can further be broken down into two more categories, Elite and Disguised. An Elite Proxy Server is not identifiable to the remote computer as a Proxy in any way. A Disguised Proxy Server gives the remote computer enough information to let it know that it is a Proxy, however it still does not give away the IP of the Computer it is relaying information for.
Popular proxy software:
Squid Web Proxy Cache (For OS: Linux)-
Has a nice set of options which make it one of the largest used Linux Proxy Servers.
Wingate Proxy Server (For OS: Windows)-
WinGate is a multi-protocol proxy server and NAT solution that can be used to redirect any kind of traffic on a Microsoft Windows host. It also provides firewall, VPN and mail server functionality. Its WWW proxy supports integrated windows authentication, intercepting proxy, and multi-host reverse-proxying.
