Overview
The ip command in Linux is a powerful utility for managing IP addresses, network interfaces, routing tables, and network namespaces. It provides granular control over various network configurations, making it an essential tool for system administrators.
Syntax
ip addr add|del IFADDR dev IFACE | show|flush [dev IFACE] [to PREFIX]
ip route list|flush|add|del|change|append|replace|test ROUTE
ip link set IFACE [up|down] [arp on|off] [multicast on|off] \
[promisc on|off] [mtu NUM] [name NAME] [qlen NUM] [address MAC] \
[master IFACE | nomaster] [netns PID]
ip tunnel add|change|del|show [NAME] \
[mode ipip|gre|sit] [remote ADDR] [local ADDR] [ttl TTL]
ip neigh show|flush [to PREFIX] [dev DEV] [nud STATE]
ip rule [list] | add|del SELECTOR ACTIONKey Features and Examples
Manage IP Addresses
View IP addresses:
ip addrAdd an IP address to a device:
ip addr add 192.168.1.1/24 dev eth0Remove an IP address:
ip addr del 192.168.1.1/24 dev eth0Flush all IP addresses for a device:
ip addr flush dev eth0Manage Network Devices
Display all network interfaces:
ip linkShow specific device details:
ip link show dev eth0Bring an interface up or down:
ip link set eth0 up
ip link set eth0 downSet MTU for a device:
ip link set eth0 mtu 1450Add or delete a bridge device:
ip link add br0 type bridge
ip link del br0Create a virtual Ethernet pair:
ip link add veth0 type veth peer name veth1Manage Routing Tables
Display the main routing table:
ip route show table mainAdd a default route:
ip route add default via 10.8.1.1 dev eth0Add a static route:
ip route add 10.8.1.0/24 via 10.8.1.1Replace an existing route:
ip route replace 10.8.1.0/24 dev eth0Flush the routing table:
ip route flush cacheManage Routing Rules
Show routing rules:
ip ruleAdd a rule to use a specific table:
ip rule add from 10.8.1.0/24 table 520Blackhole traffic from a specific source:
ip rule add from 0/0 blackholeManage Network Namespaces
List network namespaces:
ip netnsCreate a network namespace:
ip netns add s1Delete a namespace:
ip netns del s1Execute a command within a namespace:
ip netns exec s1 ip addrExample: Setting MTU
MTU (Maximum Transmission Unit) defines the maximum packet size for data transmission on a network device. Adjusting MTU impacts performance and compatibility.
View the current MTU for eth0:
ip link show eth0Set MTU to 1450 bytes:
ip link set eth0 mtu 1450Common MTU Values:
- Ethernet: 1500 bytes (default)
- PPPoE: 1492 bytes (8 bytes for headers)
- Wi-Fi: Often 1500 bytes but can vary slightly.
Quick Tips with ip
Color-coded output:
ip -c addr
ip -c routeCompact display:
ip -brief link
ip -brief addrFor detailed configuration guides, check the official documentation.