The book presents theoretical and practical knowledge that allows you to well understand the processes taking place in the network. We consider network models, protocols, addresses, services, configuring network interfaces, configuring FTP, Proxy, INN, Apache, Samba, Mars servers, discussing the network file system, Linux interaction with other operating systems. Describes the configuration of the local network: network printers, gateway to the Internet, Firewall configuration, traffic accounting, etc. There are many programs to help maintain the network and take care of its security. It describes how to create, configure and ensure reliable operation of a small local area network server capable of performing most typical tasks. For system administrators.