A firewall ignores information that comes from unsecured, unknown or suspicious locations and it plays an important role on any network as it provides a protective barrier against most forms of attack coming from the outside world. More Cisco firewall info get from RouterSwitch.com

1. Firewall, Related Review, Overview and Features You Should Know<br />Generally, a Firewall protects your computer from intrusion (scanning or attack) by hackers or script kiddies while it is connected to the Internet. A firewall examines electronic data coming in to, or out of, a computer (or network - computers joined together by wires or wireless connection) and compares it to rules it has been given. If that data matches the rules which say it is OK, it will let the data pass. If it doesn't, it blocks the data. To be simple, just think of a Firewall as a piece of software (or hardware for those with more computers) that keeps the bad guys out and let the good ones in. It stops hackers and script kiddies from gaining access to your computer and the information on it. <br />There are many people who still use the internet without thinking twice about protecting themselves when online. Most of these people are home or small business users who never give it a second thought, or just don't understand enough about the risks to worry. Using the internet without a firewall can be explained quite easily - You wouldn't leave your house or office unlocked, or with the windows and doors wide open so that anyone can walk in and look around, or even steal your items, but using the internet isn't much different than that. If you are online without a firewall you are leaving it wide open to attack, and intruders and thieves could view or steal your information. <br />So for people who use the internet, no matter it is a home, or an enterprise, a firewall is an essential hardware or software to help to protect your privacy and data on your computer by stopping hackers from gaining control of your system. <br />A firewall also prevents confidential information on your system from being sent without your permission. This could be your passwords, bank details and other personal information. <br />About Personal Firewall & Hardware Firewall <br />A Personal Firewall (also known as a desktop firewall, or Software firewall) is installed on each computer that is connected to the internet and monitors (and blocks, where necessary) internet traffic. It is used to help protect a single Internet-connected computer from intruders. Personal firewall protection is useful for users with quot;
always-onquot;
connections such as DSL, cable modem or dial-up connections.<br />Hardware firewall's can be purchased as a stand-alone product but more recently hardware firewall's are typically found in broadband routers, and should be considered an important part of your system and network set-up, especially for anyone on a broadband connection. Hardware firewalls can be effective with little or no configuration, and they can protect every machine on a local network. Most hardware firewalls will have a minimum of four network ports to connect other computers, but for larger networks, business networking firewall solutions are available. <br />Software and Hardware Firewall <br />The differences between a software and hardware firewall are vast, and the best protection for your computer and network is to use both, as each offers different but much-needed security features and benefits. Updating your firewall and your operating system is essential to maintaining optimal protection, as is testing your firewall to ensure it is connected and working correctly. <br />Notes <br />Intro of Most Popular CISCO Firewall Hardware: About Cisco ASA 5500 Series<br />Designed as a core component of the Cisco Self-Defending Network, the Cisco ASA 5500 Series provides proactive threat defense that stops attacks before they spread through the network, controls network activity and application traffic, and delivers flexible VPN connectivity. The result is a powerful multifunction network security appliance family that provides the security breadth and depth for protecting home office, branch office, small and medium-sized business, and enterprise networks while reducing the overall deployment and operations costs and complexities associated with providing this new level of security.<br />