Just after the Ubuntu installation, I came to know that the network interface name got changed to ens33 from old school eth0.

READ: Install Ubuntu 18.04 LTS (Bionic Beaver) on UEFI and Legacy BIOS System

READ: Install Ubuntu 16.04 LTS (Xenial Xerus) – Step by Step Guide with Screenshots

If you ever interested in changing interface names to old type ethX, here is the tutorial for you.

As you can see in the following command, my system is having a network adapter called ens33.

This is just the case of VMware environment, it may vary depends on the hardware but the steps to get back ethX will be the same.

$ ip a

1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state UNKNOWN group default 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: </loopback,up,lower_up>ens33: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

    link/ether 00:0c:29:05:a3:e2 brd ff:ff:ff:ff:ff:ff

    </broadcast,multicast,up,lower_up>inet 192.168.12.12/24 brd 192.168.12.255 scope global dynamic ens33

       valid_lft 1683sec preferred_lft 1683sec

    inet6 fe80::20c:29ff:fe05:a3e2/64 scope link

       valid_lft forever preferred_lft forever

From the dmesg command, you can see that the device got renamed during the system boot.

$ dmesg | grep -i eth

[    3.050064] e1000 0000:02:01.0 eth0: (PCI:66MHz:32-bit) 00:0c:29:05:a3:e2

[    3.050074] e1000 0000:02:01.0 eth0: Intel(R) PRO/1000 Network Connection

[    3.057410] e1000 0000:02:01.0 ens33: renamed from eth0

To get an ethX back, edit the grub file.

$ sudo nano /etc/default/grub

Look for “GRUB_CMDLINE_LINUX”  and add the following”net.ifnames=0 biosdevname=0“.

From:

GRUB_CMDLINE_LINUX=""

To:

GRUB_CMDLINE_LINUX="net.ifnames=0 biosdevname=0"

Generate a new grub file using the following command.

$ sudo grub-mkconfig -o /boot/grub/grub.cfg

Generating grub configuration file ...

Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.

Found linux image: /boot/vmlinuz-4.4.0-15-generic

Found initrd image: /boot/initrd.img-4.4.0-15-generic

Found memtest86+ image: /memtest86+.elf

Found memtest86+ image: /memtest86+.bin

done

Edit the interface file and change the network device name so that you will have a DHCP or static IP address for ethX.

READ: Install and configure DHCP server on CentOS 7 / Ubuntu 16.04 / Debian 9

Assign IP Address

For Ubuntu 18.04

You can assign an IP address to the system using netplan – a new network configuration tool.

READ: How To Configure Static IP Address in Ubuntu 18.04 using Netplan

For Ubuntu 16.04 / Older

DHCP:

If your infrastructure has a DHCP server and you want to leverage that, then:

$ sudo nano /etc/network/interfaces

Update below lines in /etc/network/interfaces files so that the network card can get an IP address from DHCP server.

FROM:

auto ens33

iface ens33 inet dhcp

TO:

auto eth0

iface eth0 inet dhcp

Static:

If your infrastructure does not have a DHCP server, then you will need to configure a static IP address for all network interfaces on your Ubuntu machine.

$ sudo nano /etc/network/interfaces

From:

auto ens33

iface ens33 inet static

           address 192.168.12.12

           netmask 255.255.255.0

           dns-nameservers 192.168.12.2

           gateway 192.168.12.2

To:

auto eth0

iface eth0 inet static

           address 192.168.12.12

           netmask 255.255.255.0

           dns-nameservers 192.168.12.2

           gateway 192.168.12.2

Reboot your system.

$ sudo reboot

After the system reboot, just check whether you have an ethX back.

$ ip a

1: lo: <loopback,up,lower_up> mtu 65536 qdisc noqueue state UNKNOWN group default 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: </loopback,up,lower_up>eth0: <broadcast,multicast,up,lower_up> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000

    link/ether 00:0c:29:05:a3:e2 brd ff:ff:ff:ff:ff:ff

    </broadcast,multicast,up,lower_up>inet 192.168.12.12/24 brd 192.168.12.255 scope global eth0

       valid_lft forever preferred_lft forever

    inet6 fe80::20c:29ff:fe05:a3e2/64 scope link

       valid_lft forever preferred_lft forever

That’s All.