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ip command

The ip command is the modern Linux networking utility provided by the iproute2 package. It replaces several older networking tools from the net-tools package

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ip OBJECT COMMAND [OPTIONS]
  • OBJECT specifies what you want to manage (address, link, route, neighbor, etc.).
  • COMMAND specifies the action (show, add, delete, set, flush, etc.).
Object Purpose
addr IP addresses assigned to interfaces
link Network interfaces (Ethernet, Wi-Fi, loopback)
route Routing table
neigh ARP/Neighbor cache
rule Policy routing rules
monitor Watch networking changes in real time
netns Network namespaces
tunnel GRE, IPIP, VXLAN, and other tunnels
Command Description
show Display information
add Create or add an object
del Delete an object
set Modify an existing object
replace Add or replace an existing object
flush Remove all matching entries
get Query information (for example, the route to a destination)

Demo

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# all the command are same
# object: addr
# command: show
ip addr show
ip a s
ip a

10 most useful command

  1. ip addr show
  2. ip addr add
  3. ip addr del
  4. ip route show
  5. ip route add
  6. ip route del
  7. ip neigh
  8. ss -natp
  9. ss -naup
  10. ip link set

ip addr show

full object and command
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ip addr show
brief address view with color
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ip -br -c a

ip addr add

ip addr add adds an IP address to a network interface.

Basic form:

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sudo ip addr add <ip>/<prefix> dev <interface>

Meaning:

  • <ip>/<prefix> is the IP address and subnet size
  • dev <interface> selects the network interface
  • the command changes the running network configuration

Example:

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sudo ip addr add 192.0.2.10/24 dev eth0

This adds the address 192.0.2.10 with subnet mask 255.255.255.0 to eth0.

Check it:

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ip addr show dev eth0

ip addr del

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sudo ip addr del 192.0.2.10/24 dev eth0

This change is temporary. It is lost after reboot or network service restart unless you also add it to the system network configuration.

ip route show

ip route show displays the kernel routing table.

The routing table tells Linux where to send packets.

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ip route show

Short form:

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# output with color
ip -c r

Example output:

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default via 192.168.1.1 dev wlan0
192.168.1.0/24 dev wlan0 proto kernel scope link src 192.168.1.20

Meaning:

  • default via 192.168.1.1 dev wlan0: traffic to unknown networks goes through gateway 192.168.1.1
  • 192.168.1.0/24 dev wlan0: local LAN traffic goes directly through wlan0
  • src 192.168.1.20: source IP used by this machine on that route

Show the route Linux will use for one destination:

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ip route get 8.8.8.8

ip route add

ip route add adds a route to a network.

Basic form:

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sudo ip route add <network>/<prefix> via <gateway> dev <interface>

Example:

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sudo ip route add 10.10.0.0/16 via 192.168.1.1 dev wlan0

This means:

  • packets to 10.10.0.0/16
  • should be sent to gateway 192.168.1.1
  • through interface wlan0

Add a direct route without a gateway:

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sudo ip route add 10.20.0.0/24 dev eth0

Use this when the target network is directly connected to eth0.

ip route add default

The default route is the route used when no more specific route matches.

It is usually the route to the internet through your router.

Long form:

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sudo ip route add default via 192.168.1.1 dev wlan0

Equivalent form:

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sudo ip route add 0.0.0.0/0 via 192.168.1.1 dev wlan0

Meaning:

  • default means all destinations not matched by another route
  • via 192.168.1.1 is the next-hop router
  • dev wlan0 is the outgoing interface

Check it:

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ip route show default

ip route del

ip route del removes a route.

Delete a network route:

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sudo ip route del 10.10.0.0/16 via 192.168.1.1 dev wlan0

Delete a direct route:

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sudo ip route del 10.20.0.0/24 dev eth0

Delete the default route:

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sudo ip route del default via 192.168.1.1 dev wlan0

Often this shorter command is enough:

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sudo ip route del default

Route changes made with ip route add and ip route del are temporary. They are lost after reboot or network service restart unless saved in the system network configuration.

ip neigh

ip neigh shows and manages the neighbor table.

For IPv4, this is the ARP table. It maps an IP address to a MAC address on the local network.

Show neighbor entries:

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ip neigh
# show result with color
ip -c neigh show

Show entries for one interface:

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ip neigh show dev eth0

Example output:

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192.168.1.1 dev eth0 lladdr 00:11:22:33:44:55 REACHABLE
192.168.1.50 dev eth0 lladdr aa:bb:cc:dd:ee:ff STALE

Common states:

  • REACHABLE: recently confirmed working
  • STALE: known, but not recently confirmed
  • FAILED: resolution failed
  • PERMANENT: manually configured static entry

ip neigh add

Add a static ARP entry:

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sudo ip neigh add 192.168.1.50 lladdr aa:bb:cc:dd:ee:ff dev eth0 nud permanent

Meaning:

  • 192.168.1.50 is the IP address
  • lladdr aa:bb:cc:dd:ee:ff is the MAC address
  • dev eth0 selects the interface
  • nud permanent makes it a static neighbor entry

Check it:

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ip neigh show 192.168.1.50 dev eth0

net-tools mapping

Legacy Tool Modern Replacement
ifconfig ip addr, ip link
route ip route
arp ip neigh
netstat (routing) ip route
netstat (sockets) ss