Introduction to Firewalls TEC 236

What is a Firewall? A firewall is hardware, software, or a combination of both that is used to prevent unauthorized programs or Internet users from accessing a private network and/or a single computer

What is a Firewall? A security system that acts as a protective boundary between a network and the outside world Isolates a computer or network from the “outside” based on a defined set of rules –Inspects each individual "packet" of data as it arrives at either side of the firewall –Maintains a state table –Determine whether traffic should be allowed to pass or be blocked

INTERNE T Firewall Protected Network WHO ? WHEN ? WHAT ? HOW ? My PC Rules Determine

Hardware vs. Software Firewalls Hardware Firewalls –Protect an entire network –Implemented on the router level –Usually more expensive, harder to configure Software Firewalls –Protect a single computer –Usually less expensive, easier to configure

How does a software firewall work? Inspects each individual “packet” of data as it arrives at either side of the firewall Inbound to or outbound from your computer Determines whether it should be allowed to pass through or if it should be blocked

Firewall Rules Allow – traffic that flows automatically because it has been deemed as “safe” (Ex. Meeting Maker, Eudora, etc.) Block – traffic that is blocked because it has been deemed dangerous to your computer Ask – asks the user whether or not the traffic is allowed to pass through

What a personal firewall can do Stop hackers from accessing your computer Protects your personal information Blocks “pop up” ads and certain cookies Determines which programs can access the Internet

What a personal firewall cannot do Cannot prevent viruses –Only an antivirus product with updated definitions can prevent viruses After setting it initially, you can forget about it –The firewall will require periodic updates to the rulesets and the software itself

Considerations when using personal firewall software If you did not initialize an action and your firewall picks up something, you should most likely deny it and investigate it It’s a learning process (Ex. Spooler Subsystem App) If you notice you cannot do something you did prior to the installation, there is a good chance it might be because of your firewall

Examples of personal firewall software ZoneAlarm BlackICE Defender Tiny Personal Firewall Norton Personal Firewall

Windows XP Firewall Currently *not* enabled by default Enable under Start -> Settings -> Control Panel Select Local Area Connection Select the Properties button Click the “Advanced” tab

Windows XP firewall

Updates to Windows XP Firewall *Will* be enabled in default installations of Windows XP Service Pack 2 Ports will be closed except when they are in use Improved user interface for easier configuration Improved application compatibility when firewall is enabled

Final Notes Rule Management Default Allow vs. Default Deny Firewalls do NOT Solve the Entire Problem