ifconfig vs ip

!! ALL of this was stolen from tty1.net. I liked it so much, I decided to copy it for my own reference. !!

The command /bin/ip has been around for some time now. But people continue using the older command /sbin/ifconfig. Let's be clear: ifconfig will not quickly go away, but its newer version, ip, is more powerful and will eventually replace it.

The man page of ip may look intimidating at first, but once you get familiar with the command syntax, it is an easy read. This page will not introduce the new features of ip. It rather features a side-by-side comparison if ifconfig and ip to get a quick overview of the command syntax.

Show network devices and configuration

ifconfig

ip addr show

ip link show

Enable a network interface

ifconfig eth0 up

ip link set eth0 up

A network interface is disabled in a similar way:

ifconfig eth0 down

ip link set eth0 down

Set IP address

ifconfig eth0 192.168.0.77

ip address add 192.168.0.77 dev eth0

This was the simple version of the command. Often, also the network mask or the broadcast address need to be specified. The following examples show the ifconfig and ip variants.

Needless to say that the netmask can also be given in CIDR notation, e.g. as 192.168.0.77/24.

ifconfig eth0 192.168.0.77 netmask 255.255.255.0 broadcast 192.168.0.255

ip addr add 192.168.0.77/24 broadcast 192.168.0.255 dev eth0

Delete an IP address

With ip it is also possible to delete an address:

ip addr del 192.168.0.77/24 dev eth0

Add alias interface

ifconfig eth0:1 10.0.0.1/8

ip addr add 10.0.0.1/8 dev eth0 label eth0:1

ARP protocol

Add an entry in your ARP table.

arp -i eth0 -s 192.168.0.1 00:11:22:33:44:55

ip neigh add 192.168.0.1 lladdr 00:11:22:33:44:55 nud permanent dev eth0

Switch ARP resolution off on one device

ifconfig -arp eth0

ip link set dev eth0 arp off


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