The issues of setting up network interfaces, routing, filtering traffic using basic Linux tools, network address translation (NAT) technology, as well as diagnosing network connections using ICMP protocol applications and network traffic analysis tools are discussed. The course discusses how to use the VirtualBox program to study network Linux capabilities, setting up network interfaces and routing network traffic using iproute2 packages, ifconfig, arp, route commands, configuration files of the network subsystem, features of the transport and application layers, diagnosing network connections using appropriate utilities (ping, traceroute, netstat) and network analysis traffic using tcpdump, organizing a Linux-based router, firewall and Internet access system at the network level, using virtual private network technologies. The presentation of the material is accompanied by examples typical of a small network. The examples given can be easily reproduced in the VirtualBox environment.