CentOS 7 - Rename network interface without rebooting

Question

I'm renaming network interfaces by modifying the files in /etc/sysconfig/network-scripts.

• eth0 -> nic0
• eth1 -> nic1

The content of the network scripts looks like this, after modification:

# cat /etc/sysconfig/network-scripts/ifcfg-nic0
DEVICE=nic0
BOOTPROTO=static
ONBOOT=yes
HWADDR=xx:xx:xx:xx:xx:xx
USERCTL=no
IPV6INIT=no
MASTER=bond0
SLAVE=yes

A reboot activates the new config. But how do I activate this configuration without rebooting?

A systemctl restart network doesn't do the trick.

I can shut down one interface by its old name (ifdown eth0) but ifup results in below message no matter if the old or new name was provided:

ERROR : [/etc/sysconfig/network-scripts/ifup-eth] Device nic0 does not seem to be present, delaying initialization.

/etc/init.d/network status shows this output:

Configured devices:
lo bond0 nic0 nic1
Currently active devices:
lo eth0 eth1 bond0

Both, ifconfig and ip a show the old interface names.

Answer 1

You can rename the device using the ip command:

/sbin/ip link set eth1 down
/sbin/ip link set eth1 name eth123
/sbin/ip link set eth123 up

Edit:

I am leaving the below for the sake of completeness and posterity (and for informational purposes,) but I have confirmed swill's comment and Marco Macuzzo's answer that simply changing the name and device of the interface /etc/sysconfig/network-scripts/ifcfg-eth0 (and renaming the file) will cause the device to be named correctly as long as the hwaddr= field is included in the configuration file. I recommend using this method instead after the referenced update.

You may also want to make sure that you configure a udev rule, so that this will work on the next reboot too. The path for udev moved in CentOS 7 to /usr/lib/udev/rules.d/60-net.rules but you are still able to manage it the same way. If you added "net.ifnames=0 biosdevname=0" to your kernel boot string to return to the old naming scheme for your nics, you can remove

ACTION=="add", SUBSYSTEM=="net", DRIVERS=="?*", ATTR{type}=="1", PROGRAM="/lib/udev/rename_device", RESULT=="?*", NAME="$result"

And replace it with

ACTION=="add", SUBSYSTEM=="net", DRIVERS=="?*", ATTR{address}=="00:50:56:8e:3f:a7", NAME="eth123"

You need one entry per nic. Be sure to use the correct MAC address and update the NAME field. If you did not use "net.ifnames=0 biosdevname=0", be careful as there could be unintended consequences.

Answer 2

Actually, the best answer I believe is the combination of the two answers already posted. In order to change the device name without restarting network services, use the ip link commands suggested by James Shewey (ip link set <old_device_name> name <new_device_name>).

To make the changes survive a reboot in Red Hat Linux, modify the relevant file in /etc/sysconfig/network-scripts/. Rename the file ifcfg_<old_device_name> to ifcfg_<new_device_name> and change the DEVICE variable inside to <new_device_name>. Also, make sure the HWADDR variable is set and is correct. There is no need to touch udev rules, since 60-net.rules is actually there to read the ifcfg configuration files in /etc/sysconfig/network-scripts.

Answer 3

ip link set ens33 down
ip link set ens33 name eth0
ip link set eth0 up

mv /etc/sysconfig/network-scripts/ifcfg-{ens33,eth0}

sed -ire "s/NAME=\"ens33\"/NAME=\"eth0\"/" /etc/sysconfig/network-scripts/ifcfg-eth0

sed -ire "s/DEVICE=\"ens33\"/DEVICE=\"eth0\"/" /etc/sysconfig/network-scripts/ifcfg-eth0

MAC=$(cat /sys/class/net/eth0/address)

echo -n 'HWADDR="'$MAC\" >> /etc/sysconfig/network-scripts/ifcfg-eth0

Answer 4

To restore the old naming convention, you need to edit the /etc/default/grub file and add the following

net.ifnames=0 biosdevname=0 

at the end of the GRUB_CMDLINE_LINUX variable

Answer 5

The Answer given by @James Shewey seems to be the right way to do it.

If you want to just work with the config files in /etc/sysconfig/network-scripts and then trigger a reload, unloading and loading the kernel module as mentioned by @Tom Hunt in the comments also works:

service network stop
modprobe -r igb
modprobe igb
service network start

If you access the machine remotely, make sure you run all commands in a nohup or you will lock yourself out:

nohup sh -c "service network stop && modprobe -r igb && modprobe igb ; service network start"

The driver to reload of course depends on your interface.

Answer 6

I tried the above with Vagrant / VirtualBox and ansible, but somehow this didn't work at all on my development environment.

The old interface names were maintained whatever I did until a full restart.

I added the following rules in /etc/udev/rules.d/60-persistent-net.rules (based on: https://access.redhat.com/solutions/112643)

My goal was to give the interface a specified name based on the PCI address.

Example:

ACTION=="add", SUBSYSTEM=="net", KERNELS=="0000:00:09.0", NAME:="int0"
ACTION=="add", SUBSYSTEM=="net", KERNELS=="0000:00:10.0", NAME:="ext0"

After adding those rules I executed the following commands:

ip link set eth0 down
udevadm control --reload-rules
udevadm trigger
ip link set int0 up

The error message was Cannot find device "int0" on the ip link set * up command. And in /var/log/messages I noticed the following messages

Aug 16 17:08:41 localhost ansible-command: Invoked with creates=None executable=None _uses_shell=True strip_empty_ends=True _raw_params=ip link set eth0 down && udevadm control --reload-rules && udevadm trigger && ip link set int0 up#012 removes=None argv=None warn=True chdir=None stdin_add_newline=True stdin=None
Aug 16 17:08:41 localhost NetworkManager[6989]: <info>  [1565975321.5971] device (eth6): state change: disconnected -> unavailable (reason 'carrier-changed', sys-iface-state: 'managed')
Aug 16 17:08:41 localhost systemd-udevd: Network interface NamePolicy= disabled on kernel command line, ignoring.

But the following did work by accessing the VM through VirtualBox and execute the following commands to remove and re-add the kernel module.

rmmod e1000 
modprobe e1000

I found this in the following thread: https://www.centos.org/forums/viewtopic.php?t=54695

The strange thing I noticed was that lsmod gives me (note the Used by)

[vagrant@node-01 ~]$ lsmod
Module                  Size  Used by
e1000                 137586  0