Mastering ifconfig: How to View and Configure Network Interfaces on Linux

ifconfig: Display or configure network parameters

Function description

The ifconfig command is used to display or configure network parameters of host network interfaces, such as setting IP addresses, modifying MAC addresses, and bringing interfaces up or down.

Configurations made with ifconfig are temporary; they disappear after a reboot. To make changes permanent, edit the network interface configuration files.

Command syntax

ifconfig [interface] [options] [IP address]

Option meanings

-a : Show the status of all network interfaces

up : Bring the specified network device up

down : Bring the specified network device down

add <address> : Set an IPv6 address on the network device

del <address> : Delete an IPv6 address from the network device

IP address : Specify the IPv4 address for the network device

netmask <subnet mask> : Set the subnet mask for the network device

mtu <bytes> : Set the Maximum Transmission Unit for the network device

hw <type> <hardware address> : Set the hardware MAC address of the interface

Reference examples

Example 1: View network interfaces

// Show active network interfaces only
# ifconfig

// Show all network interfaces, regardless of state
# ifconfig -a

// Show information for a specific interface (e.g., ens33)
# ifconfig ens33

Example 2: Bring an interface up or down

// Bring interface ens33 up
# ifconfig ens33 up

// Bring interface ens33 down
# ifconfig ens33 down

Example 3: Configure IP, change MAC address

// Set IP address and activate the device
# ifconfig ens33 192.168.154.131 netmask 255.255.255.0 up

// Add an IPv6 address
# ifconfig ens33 add 33ffe:3240:800:1005::2/64

// Delete an IPv6 address
# ifconfig ens33 del 33ffe:3240:800:1005::2/64

// Change the hardware MAC address
# ifconfig ens33 hw ether 00:0c:29:8e:14:c3

Example 4: Configure an alias interface

// Create alias eth33:1 with a /16 netmask IP
# ifconfig ens33:1 192.169.1.6 netmask 255.255.0.0

// Bring the alias interface down
# ifconfig ens33:1 down

Other examples

// Enable ARP protocol on the interface
# ifconfig ens33 arp

// Disable ARP protocol on the interface
# ifconfig ens33 -arp

// Set the maximum packet size (MTU) to 1500 bytes
# ifconfig ens33 mtu 1500