Firewalls

Why Do we need Security

The issue of security involves a large number of concepts and protocols that can be used to ensure privacy when needed to protect information passed between networks.

The ability to connnect to any computer anywhere is phenomenal but it has its share of problems.
It allows individual users to surf the net but for private networks it can be testing. Most corporations have confidential information such as trade secrects product development plans, etc.

Additionally , besides leaking out information , there is also the danger of leaking in .In particular viruses and worms can breach security and data and cause you to waste a lot of time trying to clean up the mess.

Consequently mechanism are needed to control data flow in and out . One method is to use encryption .This approach protects data intransit between secure sites. It does not however keep out digital pests and hackers.

Firewall

Firewall , is a checkpoint for data going and leaving a network. The basic configuration of a firewall has two components :-

2 routers that do packet filtering
an application gateway

There is no other route for immigrating or emmigrating packets.
Each packet filter is a router with additional functionality for inspecting incoming and outgoing packet. The packet filter on the inside LAN checks incoming packets . Packets then go the application . The filters are put on different LANS to ensure no packets get in or out without passing through the application gateway .

The application gateway looks at the info passing in and out so it can check for keywords/files etc. Mail gateway can check for header field, message size and maybe content. If the machines use wireless communication ,the information passses over the firewall.Therefore afirewall is not secure for these purposes and other methods of security will have to be established.