What is a firewall?

In a nutshell, it acts as a barrier between your computer and the internet. To protect you from crackers, hackers and malware.

If your running DSL or cable modem is necessary to use a firewall, as having a direct connection to the Internet can make you a target to attack.

Firewalls can be hardware or software based. With the firewall set ACL or access control lists to allow or block traffic.

There are three ways a firewall can block traffic.

1. Packet Filtering packets are analyzed against filters in the firewall ruleset. Firewall drops packets that are not allowed in the firewall rules.

2. Proxy-Service information from the Internet is grabbed by the firewall and delivered to the requesting service via the proxy.

3. The stateful packet inspection-criteria search against a database of reliable information. To see if the package contains everything that would allow

or deny network.

Firewalls are customizable allowing you to create your own set of rules you can block IP addresses, specific protocols such as Telnet, FTP, ICMP, UDP, SMTP and
many others.

The firewall can be customized to block specific ports, or even keywords.

There are many software firewall availiable as http://www.tinysoftware.com/home/tiny2?la=EN Tiny Firewall that is designed to keep hackers out by the network and Spyware block.

Zone Labs ZoneAlarm makes me like it bcause it has a simple interface that allows home users to easily configure. http://www.zonelabs.com/store/content/home.jsp

For hardware firewall is:

There http://www.cisco.com Cisco brand is called PIX firewall.

From home users I like D-Link DI-604 is a firewall that works well economically. Best of all it fits in almost any budget.

Linksys (now part of Cisco) offers a router / firewall that supports VPN and DMZ.
http://www.linksys.com

There are hardware solutions including the creation of a firewall on a * nix box. I like this better because it gives the administrator complete control of the firewall. Personally, as OpenBSD for all security applications that would run with Unix, since it is safe. There were very few exploits against this platform.

I'll write more articles about firewalls shortly .......