What is Firewall?

By | July 21, 2009

A firewall is software written for the purpose of securing your computer from the threats like hacking, Viruses and worms that try to enter your system from the network. Using firewall is the first step to make your system secured. It is the device or set of devices which is configured to either permit or deny , encrypt and decrypt the traffic  between the domain in regards to the security rules set.

Please always turn ON your firewall before connecting to the internet.

A Firewall can be software, hardware or combination of both.

There are several types of firewall techniques:

1.       Packet filter Firewall: In this firewall, each packet coming to or leaving the network is monitored and decision is taken whether to accept or deny based on the rules set. This technique is very effective and well appreciated, however it is somewhat difficult to configure.

2.       Stateful firewall: This firewall is similar to packet filter firewall, however it is more intelligent in tracking the connections which are active. Configuring rues is easy and in deeper way.

3.       Application Gateway Firewall:  This technique is useful in some applications such as Telnet servers and FTP Servers. This firewall can bring performance degradation to the network.

4.       Circuit Level Gateway: This firewall is activated only when TCP or UDP connection is made. Once the connection is established the packets can traverse in the network without further filtering process.

5.       Proxy server: This is widely used in an enterprise. It checks each and every packet in the network. The proxy server also hides the network address

Basic way the Firewall is configured.

A firewall can be configured in either of the two basic ways given below.

Default Deny: The firewall lists the network services that are allowed and everything else is denied.

Default Allow: The Firewall lists the network services which are not allowed and everything else is allowed.

Need of firewall:

If the computer is not secured with the firewall and connected to the internet. The hackers can easily gain access to your system and exploit with your system The intruder can install code on your system that destroys files or may do some malfunctioning. This is firewall helps you out, It screen outs many kinds of malicious traffic before it reaches the system.

Only firewall doesn’t make your system completely secure. This is baseline securing your system. You should install additional security measures. Antivirus software is a good for your system