Introduction

Being knowledgeable about the commands associated with the manipulation of the network stack of the Linux operating system is important for Linux system administrators. Most of the commands that allow users to modify the networking of the system also allow us to obtain information about the servers’ network setup. This information includes mainly IP addresses and routing tables. In this article, we will look at five different ways by which we can display the IP address information about our server.

For the purpose of this demonstration, we will be working on a Centos 7 system.

Method 1: Using ifconfig command
The ifconfig command is the most commonly used command for displaying and modifying IP addresses on the system. The name ifconfig is short for interface configuration. When used without any options or when used with the -a option it displays information about the interfaces available on the system and the IP address set on those interfaces.

[root@linuxnix ~]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.23.131 netmask 255.255.255.0 broadcast 192.168.23.255
inet6 fe80::830:c411:78b:6bb9 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:7e:5f:4f txqueuelen 1000 (Ethernet)
RX packets 810 bytes 80806 (78.9 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 394 bytes 54734 (53.4 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

If you are working on a script and want only the IP address to be shown then you can use a quick one liner awk command that we’ve come up with.

[root@linuxnix ~]# ifconfig | awk '/inet 19/ {print $2}'
192.168.23.131
[root@linuxnix ~]#

You can replace the 19 with the network prefix for your network which is commonly 10 for networks in most enterprises.

Method 2: Using ip command
The ifconfig command although still commonly used is considered to be deprecated and the ip command is the one that has taken its place. The ip command, when used with the ‘a’ or ‘addr show’ options, provides the same information as the ifconfig command.

[root@linuxnix ~]# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:7e:5f:4f brd ff:ff:ff:ff:ff:ff
inet 192.168.23.131/24 brd 192.168.23.255 scope global dynamic ens33
valid_lft 1473sec preferred_lft 1473sec
inet6 fe80::830:c411:78b:6bb9/64 scope link
valid_lft forever preferred_lft forever
[root@linuxnix ~]#
[root@linuxnix ~]# ip addr show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: ens33: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
link/ether 00:0c:29:7e:5f:4f brd ff:ff:ff:ff:ff:ff
inet 192.168.23.131/24 brd 192.168.23.255 scope global dynamic ens33
valid_lft 1345sec preferred_lft 1345sec
inet6 fe80::830:c411:78b:6bb9/64 scope link
valid_lft forever preferred_lft forever
[root@linuxnix ~]#

Method 3: Using the hostname command
The hostname command when invoked with the -I option displays IP addresses set on currently active interfaces.

[root@linuxnix ~]# hostname -I
192.168.23.131
[root@linuxnix ~]#

Method 4: using nmcli command
The nmcli command is a command line tool for creating, editing, displaying, deleting, activating and deactivating connections. When used without any options it displays the interfaces active on the system and the IP addresses set on those interfaces.

[root@linuxnix ~]# nmcli
ens33: connected to ens33
"Intel 82545EM Gigabit Ethernet Controller (Copper) (PRO/1000 MT Single Port Adapter)"
ethernet (e1000), 00:0C:29:7E:5F:4F, hw, mtu 1500
inet4 192.168.23.131/24
inet6 fe80::830:c411:78b:6bb9/64

lo: unmanaged
loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.

Consult nmcli(1) and nmcli-examples(5) manual pages for complete usage details.

The “nmcli device show” displays more in-depth information about the interfaces.

[root@linuxnix ~]# nmcli device show
GENERAL.DEVICE: ens33
GENERAL.TYPE: ethernet
GENERAL.HWADDR: 00:0C:29:7E:5F:4F
GENERAL.MTU: 1500
GENERAL.STATE: 100 (connected)
GENERAL.CONNECTION: ens33
GENERAL.CON-PATH: /org/freedesktop/NetworkManager/ActiveConnection/0
WIRED-PROPERTIES.CARRIER: on
IP4.ADDRESS[1]: 192.168.23.131/24
IP4.GATEWAY:
IP4.DNS[1]: 192.168.23.1
IP4.DOMAIN[1]: localdomain
IP6.ADDRESS[1]: fe80::830:c411:78b:6bb9/64
IP6.GATEWAY:

GENERAL.DEVICE: lo
GENERAL.TYPE: loopback
GENERAL.HWADDR: 00:00:00:00:00:00
GENERAL.MTU: 65536
GENERAL.STATE: 10 (unmanaged)
GENERAL.CONNECTION: --
GENERAL.CON-PATH: --
IP4.ADDRESS[1]: 127.0.0.1/8
IP4.GATEWAY:
IP6.ADDRESS[1]: ::1/128
IP6.GATEWAY:

Method 5: Using ip route show command
We can use the ip route show command to display information about interfaces and assigned IP addresses but we need to pipe the output to awk or grep to filter out the required results.

[root@linuxnix ~]# ip route show | awk 'BEGIN {print "IFace", "Address"} /dev/ {print $3" "$9}' | uniq
IFace Address
ens33 192.168.23.131
[root@linuxnix ~]#

Conclusion

This concludes our demonstration on different commands you could use to find IP address information on your system. We hope that you’ve found this article to be useful and we look forward to your suggestions and feedback.

Post Views: 33,832
The following two tabs change content below.

Sahil Suri

He started his career in IT in 2011 as a system administrator. He has since worked with HP-UX, Solaris and Linux operating systems along with exposure to high availability and virtualization solutions. He has a keen interest in shell, Python and Perl scripting and is learning the ropes on AWS cloud, DevOps tools, and methodologies. He enjoys sharing the knowledge he's gained over the years with the rest of the community.