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Crash Course: Firewalls

Firewalls aren't as simple as they used to be. Use our Crash Course to learn the latest and make sure your firewall is right for your network.

Firewalls aren't as simple as they used to be. Use our Crash Course to learn the latest and make sure your firewall is right for your network.


A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks. (The term also implies the security policy that is used with the programs.) An enterprise with an intranet that allows its workers access to the wider Internet installs a firewall to prevent outsiders from accessing its own private data resources and for controlling what outside resources its own users have access to.

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Introduction to firewalls
Get the basics on firewalls with this introductory tip.

Firewall redundancy: Deployment scenarios and benefits
Learn the benefits and riskes of deploying dual firewalls on your network.

Troubleshooting firewalls
How to troubleshoot your firewall's settings when it is preventing a client or server connection.

A manager's guide to firewall logs
Few IT managers bother to review firewall logs to stay informed about the security of their networks. They should.

The router is the firewall
Expert Michael Martin examines the available options in the IOS firewall for implementing dynamic access control.

Read more firewall-related tips here.


Which is better - a firewall appliance or a dedicated machine running firewall software?
Expert response: It's a fact that firewalls are moving to appliances and the reason behind it is to make them as secure as possible. It's not the appliance itself, which makes a...

Which is more beneficial, a router and a firewall or a router with a built in firewall?
Expert response: You can go for any of the options depending upon your requirement. Most of the Cisco routers are available with the software firewall and IOS options...

Determining a set of base rules on a firewall
Expert response: Please don't be offended, but this question raised my concern level quite a bit. It seems there is a lack of a fundamental process to determine the...

Ask our security experts your firewall-related questions and view previously answered Q&As.


Firewalls For Dummies, Chapter 1
Chapter 1 of Firewalls For Dummies by Brian Komar, Ronald Beekelaar and Joern Wettern provides an excellent overview of what a firewall is, what it does and how it works. Further it explains when you might need a firewall, covering issues like Internet protocols, security and hacking.

Cisco Router Firewall Security, Chapter 17
Chapter 17 of Cisco Router Firewall Security covers denial of service attacks and how to stop them, including TCP Intercept, CBAC and rate limiting.

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This was last published in December 2005

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