Ifconfig

ifconfigis a command in Unix-like operating systems like Linux, FreeBSD, OpenBSD, macOS for Ethernet network interface configuration.

In macOS, the ifconfig command functions as a wrapper to the IPConfiguration agent, and can control the BootP and DHCP clients from the command-line. Use of ifconfig to modify network settings in Mac OS X is discouraged, because ifconfig operates below the level of the system frameworks which help manage network configuration. To change network settings in Mac OS X from the command line, use /usr/sbin/ipconfig or /usr/sbin/networksetup.

ifconfig command is included in the net-tools package but not installed by default in RHEL since version 7.

Configuring an alias IP

Linux alias

ifconfig eth0:0 192.168.1.6 up

ifconfig eth0:0
eth0:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.1.6  netmask 255.255.255.0  broadcast 192.168.1.255
        ether 33:54:00:7d:35:22  txqueuelen 1000  (Ethernet)

macOS alias

Configure 3 alias in en1 interface, https://ss64.com/osx/ifconfig.html:

sudo ifconfig en1 inet 192.168.10.2/24 add
sudo ifconfig en1 inet 192.168.20.2/24 add
sudo ifconfig en1 inet 192.168.30.2/24 add

or

sudo ifconfig en1 inet 192.168.10.2/24 alias
sudo ifconfig en1 inet 192.168.20.2/24 alias
sudo ifconfig en1 inet 192.168.30.2/24 alias

Remove/delete alias:

sudo ifconfig en1 inet 192.168.10.2/24 delete

ifconfig eth# up or ip link set eth0 up

Activities

• Show interface configuration in Linux including ip addresses: ifconfig -a or ip a
• Show interface Ethernet network capabilities of your interface, such as speed, with: mii-tool -v YOUR_INTERFACE_NAME, mii-tool -v eth0
• Show all network interfaces in Linux:
• Learn about Linux Naming Schemes Hierarchy.

• Change your MAC address: ifconfig {eth0|wlan0} hw ether CA:CA:CA:CA:CA:CA

Related terms

• docker inspect CONTAINER_NAME | grep IPAddress

See also

• Linux networking: Consistent Network Device Naming (eth, ens), DPDK, Alias IP, bonding, Wlan0, ip [link, route], ifconfig netstat ss lsof ping ethtool mii-tool arping nmcli(RHEL) route networkctl, netplan, tc
• ipconfig Windows command
• macOS: networksetup, ifconfig, ipconfig [ getifaddr ] , scutil
• bonding

References

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Source: https://en.wikiversity.org/wiki/Ifconfig