This book is designed as an administration, networking, and security reference. Administration tools are covered as well as the underlying configuration files and system implementations. The emphasis is on what administrators will need to know to perform key administration and security tasks. Topics covered include user management, time server settings, start up configuration, software management, kernel configuration, SELinux, and file system management. Server tools are covered as well as the underlying configuration files and system implementations. Topics covered include network connections, IP network administration, software management, Upstart service management, runlevels, and the Network Time Protocol. Key servers are examined, including Web, FTP, CUPS printing, NFS, and Samba Windows shares. Network support servers and applications covered include the Squid proxy server, the Domain Name System (BIND) server, DHCP, and IPtables firewalls.