Textbook of Linux

ip is the primary command for configuring Linux networking in the iproute2 suite. It replaces the older ifconfig, route, arp, and others with a unified, powerful tool. Every interface, address, route, and tunnel is managed through ip, and modern distributions no longer install the legacy tools by default.

ip addr                                  # show addresses
ip link                                  # show links
ip route                                 # routing table
ip -s link show eth0                     # interface stats
sudo ip link set eth0 up                 # bring interface up
sudo ip addr add 192.0.2.10/24 dev eth0  # assign address
sudo ip route add default via 192.0.2.1  # add default route
ip neigh                                 # ARP/neighbour table
ip netns                                 # network namespaces

The subcommands cover every modern feature: tunnels (ip tunnel), rules (ip rule), multi-table routing, policy routing, VRFs, and network namespaces (which containers depend on). It can also configure VLANs, bridges, bonds, and TUN/TAP interfaces.

For temporary changes, ip commands take effect immediately but do not persist across reboots. Persistent configuration is handled by distribution-specific tools: /etc/network/interfaces (Debian), NetworkManager (most desktops), systemd-networkd (modern minimal systems), or netplan (Ubuntu).