While corporate system administrators spend lots of time thinking about enterprise firewall systems for their in-house employees, a vulnerability that is often overlooked is the remote employee's unprotected computer system, the unprotected computers of mobile laptop users (employees on the road) and all those unprotected but networked handheld devices. At the same time, many home computer users who have always relied on high speed Internet access don't realize that without a personal firewall, they too are quite vulnerable to intrusion and attacks. This book is designed to explain how personal firewalls work and how to determine which type of firewall works best in a given situation. Yeo starts with an intro to security basics -basic data protection measures (passwords, virus software, encryption, and firewalls) and reviews common vulnerabilities and issues with the always-on Internet. Yeo then explains protection methods used by firewalls in general - proxy server firewalls, packet filters, signature-based firewalls and stateful inspection-based firewalls while examining strengths and weaknesses of each type. She then explains how each type of protection method is implemented in a "personal" firewall, the various products including Black Ice Defender, Zone Alarm, Linux iptables that use a given firewall method, and the pros and cons of relying on this method in a personal firewall. An entire chapter is devoted to maintenance of personal firewalls.