Concentrating on Linux installation, tuning, and administration, this guide to protecting systems from security attacks demonstrates how to install Linux so that it is tuned for the highest security and best performance, how to scan the network and encrypt the traffic for securing all private traffics in a public network, and how to monitor and log the system to detect potential security problems. Backup and recovery policies that provide a structure for secure operations are also considered, and information related to configuring an Apache server, e-mail service, and the Internet gateway using a proxy server, an FTP server, DSN server for mapping DNS names to IP addresses, and firewall for system protection is provided.