Change Linux CentOS Ethernet Interface Name to Default eth0 - NETSEC


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Thursday, April 16, 2020

Change Linux CentOS Ethernet Interface Name to Default eth0

Check Network Interface information:
  • ip a
  • ip l
  • nmcli d
  • nmtui

Disable Consistent Interface Device Naming

To regain the ethX back, edit the grub file.

vi /etc/default/grub
Look for GRUB_CMDLINE_LINUX and add or change to the following net.ifnames=0.

GRUB_CMDLINE_LINUX="crashkernel=auto resume=/dev/mapper/cl-swap rhgb quiet"
GRUB_CMDLINE_LINUX="crashkernel=auto resume=/dev/mapper/cl-swap net.ifnames=0 rhgb quiet"

[root@centos7-test1 ~]# ip addr show

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ens3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9000 qdisc pfifo_fast state UP group default qlen 1000
    link/ether 02:00:17:00:b1:dc brd ff:ff:ff:ff:ff:ff
    inet brd scope global dynamic ens3
       valid_lft 86202sec preferred_lft 86202sec
    inet6 fe80::17ff:fe00:b1dc/64 scope link
       valid_lft forever preferred_lft forever
[root@centos7-test1 ~]# vi /etc/default/grub
[root@centos7-test1 ~]#  grub2-mkconfig -o /boot/grub2/grub.cfg
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-1062.12.1.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.12.1.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-1062.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-1062.el7.x86_64.img
Found linux image: /boot/vmlinuz-3.10.0-229.1.2.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-229.1.2.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-64cb9cb13e6a425f9bca6c461e593eb3
Found initrd image: /boot/initramfs-0-rescue-64cb9cb13e6a425f9bca6c461e593eb3.img
Found linux image: /boot/vmlinuz-0-rescue-5eef1a77fa764e12a0a38a6c52d9818b
Found initrd image: /boot/initramfs-0-rescue-5eef1a77fa764e12a0a38a6c52d9818b.img

[root@centos7-test1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-ens3
# Generated by dracut initrd
[root@centos7-test1 ~]# mv /etc/sysconfig/network-scripts/ifcfg-ens3 /etc/sysconfig/network-scripts/ifcfg-eth0
[root@centos7-test1 ~]# systemctl disable NetworkManager
[root@centos7-test1 ~]#
[root@centos7-test1 ~]# 

Before reboot :
[root@centos7-test1 ~]# vi /etc/sysconfig/network-scripts/ifcfg-eth0

Change ethernet name from ens3 to eth0.

rm '/etc/systemd/system/'
rm '/etc/systemd/system/dbus-org.freedesktop.NetworkManager.service'
rm '/etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service'

But still in next reboot it might change to earlier one, for this we have to make them persistent through editing it system file named /usr/lib/udev/rules.d/60-net.rules
[root@host1 ~]# cat /usr/lib/udev/rules.d/60-net.rules
ACTION=="add", SUBSYSTEM=="net", DRIVERS=="?*", ATTR{address}=="52:54:00:5f:d0:28", NAME="eth0"

Now we permanent rename Network Ethernet cards name to required one.
[root@WesternStar rules.d]# pwd


[root@WesternStar rules.d]# cat 70-persistent-net.rules |grep -v \#

SUBSYSTEM=="net", ACTION=="add", DRIVERS=="?*", ATTR{address}=="52:54:00:4e:40:9a", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

[root@WesternStar rules.d]#

[root@centos7-test1 ~]#reboot

Unmask NetworkManager Service

nmtui is the command to launch NetworkManager. In previous section, we have disabled and masked this serviec. Here is the step to unmask and enable it.
[root@centos7-test1 ~]# systemctl list-unit-files | grep Network
NetworkManager-dispatcher.service             disabled
NetworkManager-wait-online.service            masked
NetworkManager.service                        masked
[root@centos7-test1 ~]# systemctl unmask NetworkManager
Removed symlink /etc/systemd/system/NetworkManager.service.
[root@centos7-test1 ~]#  systemctl start NetworkManager
[root@centos7-test1 ~]# nmtui

[root@centos7-test1 ~]# systemctl status NetworkManager

[root@centos7-docker-portainer ~]# systemctl unmask NetworkManager.service
Removed symlink /etc/systemd/system/NetworkManager.service.
[root@centos7-docker-portainer ~]# systemctl unmask NetworkManager-wait-online.service
Removed symlink /etc/systemd/system/NetworkManager-wait-online.service.

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