The ifconfig command, a traditional tool used in Unix-like operating systems, configures and manages network interfaces. Although the ip command has largely replaced it in modern Linux distributions, ifconfig remains useful and available on many systems.
use case #1: Displaying Information on All Network Interfaces Available on the System:
Using (ifconfig)
- To list all network interfaces and their configurations, use:
- This command shows IP addresses, netmasks, broadcast addresses, and the current status of each interface.
use case #2: Displaying Information on All Network Interfaces Available on the System:
Using (ifconfig -a)
- To display only the active (up) interfaces, use.
- This command shows detailed information for all interfaces, including those that are not currently active.
use case # 3 Assigning an IP Address to an Interface:
- To assign an IP address to a specific interface, use.
sudo ifconfig <interface> <IP_address> netmask <netmask>
- For example, to set the IP address 192.168.1.10 with a netmask of 255.255.255.0 to the eth0 interface.
root@ip-172-31-22-37:~#sudo ifconfig eth0 192.168.1.10 netmask 255.255.255.0
use case # 4 Altering Status of Network Interfaces:
- To bring an interface up or down, use.
sudo ifconfig <interface> up
sudo ifconfig <interface> down
For example, to bring lo up:-
root@ip-172-31-22-37:~#sudo ifconfig lo up
And to bring it lo down:-
root@ip-172-31-22-37:~#sudo ifconfig lo down
use case # 5 Setting MTU Size of an Interface:
- To set the Maximum Transmission Unit (MTU) size for an interface, use.
sudo ifconfig <interface> mtu <size>
- for instance, to set the MTU size to 1500 on eth0.
root@ip-172-31-22-37:~#sudo ifconfig enX0 mtu 1500
use case # 6 Enabling/Disabling Promiscuous Mode:
- To enable or disable promiscuous mode (where the network interface captures all packets, not just those addressed to it), use:
sudo ifconfig <interface> promisc
sudo ifconfig <interface> -promisc
- For example, to enable promiscuous mode on eth0:
root@ip-172-31-22-37:~#sudo ifconfig eth0 promisc
And to disable it:
root@ip-172-31-22-37:~#sudo ifconfig eth0 -promisc
- While ifconfig is useful, you might also want to explore the ip command, which offers more comprehensive functionality and is the preferred tool in many modern Linux environments.
