FIREWALL AND PROXY

                

The firewall approach is to allow local users use internet safely. Firewall goal is to control all the traffic between the  local network and the internert. The traffic must be handeled in such a way that  no intruder or hacker can reach or infect the network.

NEEDS OF FIREWALL-

Local network connected directly to the internet without any firwall are open invitation to the intruders. Consider a large network with thousand of users. If every host is allowed to communicate directly with the outside world, the hacker will find weakest host and find its way inside the networl for themselves. And if one of the host is penetrated by the attacker than it is no difficult to reach the other at all as they are interconnected .But if a local network is covered with the firewall there is direct access to only selected subsets of the host  and security policies can easily be implemented.

In gernal firewall are the software program  which does not allow outsider to access the network.

Proxy

Proxy server accomplish the following

1 Accept client session and appear to them as server

2)Receive the name of actual server and appear to it as actual client

3) Relay all the data from clent to server

 A proxy server receive a request  for an internet service from a user. If it passes filtering requirement it looks in its local cache of previously downloaded pages. If it find it passes it to the user without forwarding the request to the internet . but if it does not find the page in the local cache the proxy server act as a client on behalf of the user and send the request  for the page to the internet using one of  its IP and when the request return the proxy server compare it with the original request of the user and then send it to the user. It is mainly used to surf internet unidentified.