If you need to configure network interfaces on Debian systems, the ifconfig command is your go-to tool. This command is usually used during the installation process of a Linux-based system, but it can also be used to manage changes later on. In this blog post, we’ll go through the proper usage of ifconfig on Debian systems.
First, let’s go over the basics. The ifconfig command is used to view and configure network interface information, such as IP addresses and associated devices. This command is typically found in all Linux system distributions, including Debian.
If you’d like to obtain a quick overview of the available network interfaces on your system, you can use the ifconfig command without any options. This will display information regarding all available network interfaces on your system, including their IP addresses.
$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:0a:95:9d:68:16
inet addr:192.168.1.100 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:206290 errors:3 dropped:0 overruns:0 frame:0
TX packets:194248 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:125814645 (125.8 MB) TX bytes:15757932 (15.7 MB)
lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:8 errors:0 dropped:0 overruns:0 frame:0
TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:480 (480.0 B) TX bytes:480 (480.0 B)
If you would like to change one of the network interfaces, the ifconfig command also accepts a variety of options that can be used to set IP addresses, subnet masks, and other parameters. For example, if you want to assign an IP address of 192.168.1.200 to the eth0 network interface, you can use the following command:
$ sudo ifconfig eth0 192.168.1.200
You may also need to set a network’s broadcast address, in which case the netmask option is used to specify the network’s mask address. In this example, we’ll set a broadcast address of 192.168.1.255 and a netmask of 255.255.255.0.
$ sudo ifconfig eth0 broadcast 192.168.1.255 netmask 255.255.255.0
You can verify the changes by using the ifconfig command again. This will display all the network configuration information for the eth0 interface.
$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:0a:95:9d:68:16 inet addr:192.168.1.200 Bcast:192.168.1.255 Mask:255.255.255.0 UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:206290 errors:3 dropped:0 overruns:0 frame:0 TX packets:194248 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:125814645 (125.8 MB) TX bytes:15757932 (15.7 MB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:8 errors:0 dropped:0 overruns:0 frame:0 TX packets:8 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:480 (480.0 B)
