Firewalls

The firewall is the part of the computer system or network which is designed to block any unauthorized access whilst permitting authorized communications. The firewall is a device which is configured to deny, permit, proxy, encrypt, decrpyt all computer traffic (in or out of the computer) which is between any different security domains. The firewall can be impletemented in either hardware or software or even both. The firewall is most commonly used to prevent unauthorized users accessing private networks which are connected to the internet. Every message that is passed into and out of the computer are passed through the computer and are examined thoroughly to check that they meet the specified security criteria. There are many different types of firewall techniques including: Packet filter and a Proxy server. A Packet filter inspects each packet passing through the network and can either accept or reject it based on user defined rules. It is effective and most transparent to its users. However it is harder to configure. The proxy server intercepts all messages entering and leaving the network. The proxy server effectively hides the network addresses.