The following steps will disable NetworkManager service and allows the interface to be managed only by network service.
1. To check which are the interfaces managed by NetworkManager
# nmcli device status
This displays a table that lists all network interfaces along with their STATE. If Network Manager is not controlling an interface, its STATE will be listed as unmanaged. Any other value indicates the interface is under Network Manager control.
2. Stop the NetworkManager service:
# systemctl stop NetworkManager
3. Disable the service permanently:
# systemctl disable NetworkManager
4. To confirm the NetworkManager service has been disabled
# systemctl list-unit-files | grep NetworkManager
5. Add the below parameter in /etc/sysconfig/network-scripts/ifcfg-ethX of interfaces that are managed by NetworkManager to make it unmanaged.
Enable network service
1. Install network scripts from repo. This provides the start scripts that are required.
yum install network-scripts -y
2. Enable the network service
# systemctl enable network
3. Restart the network service
# systemctl start network
That’s it, easy peasey