WEB PROXYSERVER A Presentation on Proxy ServerVikas Reddy Merugu
WEB PROXY SERVER• It is a specialized HTTP Server.• Functions as a firewall. • Protects client computers from Hackers by limiting outside access to clients.• Allows all clients connected to Web Proxy Server to access Internet from behind “firewall.”• Client computer(s) are allowed access past firewall with minimum effort and without compromising security.
HOW DOES IT WORKS ?• Web Proxy Server listens for any request from clients.• All requests are forwarded to remote internet servers outside firewall.• Also listens for responses or request from outside the firewall (external servers) and sends to them to internal client computers.• Usually, all clients with a subnet use the same proxy server.• This makes it possible for the proxy server to cache documents that are requested by one or more clients (repeatedly).
CONTINUE…• For clients using a web proxy server, it is as if they are getting responses directly from a remote server.• Clients without a Domain Name Service can still access the Web• All that is needed is the proxy server’s IP address.• Most Web Proxy Servers are implemented on a per-access method basis. • It can allow or deny internet requests according to the protocol used. • For Example: A proxy server can allow calls to FTP while but deny calls to HTTP servers.
HOW DO BROWSERS ACCESSINTERNET ?• In some cases, certain browsers cannot access the Web because they are behind a firewall.• In these cases, the web proxy server can retrieve any desired files for them.
CONTROLLING ACCESS TOINTERNET• Web proxy server makes it possible to filter client “transactions” at the protocol level.• Controls access to services for individual methods, hosts, as well as domains.• For Example, web proxy servers allows administrators to: • Decide which requests to grant permission to and which ones to turn down. • Specify the URL(s) masks of locations that you don’t want the proxy server to serve. • Specify which protocols clients can use the services based on their IP address.
COMMUNICATING THROUGHPROXY SERVER• The Proxy server acts as both a server system and a client system.• The proxy server uses the header fields passed to it by the browser without modification when it connects to the remote server.• A complete proxy server should be able to communicate all the Web protocols, the most important ones being HTTP, FTP, Gopher, and WAIS.• When a browser sends a request through a proxy server, the browser always uses HTTP for the transactions with the proxy server.
HOW PROXY ACCESS CONTROLWORKS ?• Scenario: an off-site (or off-campus) user connects to the Internet via an ISP and wants to connect to an IP- restricted resource:- user Y from outside internal network requests access to internal resource- proxy server prompts user Y for validation.- user Y is validated (proxy server masks user Ys IP- address)- resource.com assumes user Y is an institutional computer