ifconfig vs ip
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 ifconfigand ip to get a quick overview of the command syntax.
Show network devices and configuration ¶
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 192.168.1.255 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