Modern Linux distributions have shifted from the legacy network service to NetworkManager, particularly since RHEL 7. This change addresses the increasing complexity of network parameters and provides a unified configuration layer. Instead of manually editing files and restarting services to load configurations into kernel memory, NetworkManager manages state dynamically.

Verify the service status:

systemctl status NetworkManager

Identify hardware bus info:

lshw -class net -businfo

Three interfaces exist for configuration:

1. GUI: nm-connection-editor (requires X11 forwarding or local GUI).
2. TUI: nmtui (terminal-based pseudo-graphical).
3. CLI: nmcli (command-line interface).

Device Management via nmcli

Check physical interface status:

nmcli dev status

Columns indicate device name, type, state, and associated connection profile. States include unmanaged (ignored by NM), disconnected (no profile), connected (active), or connecting.

Disconnect a specific interface:

nmcli dev disconnect eth0

Reconnect using the assigned profile:

nmcli dev connect eth0

View detailed device properties:

nmcli dev show eth0

Connection Profile Menagement

Profiles are stored internally and often correlate with files in /etc/sysconfig/network-scripts/ (legacy compatibility).

List existing profiles:

nmcli con show

Create a new Ethernet profile with static IP:

nmcli con add type ethernet ifname eth0 con-name "Corp-LAN" ipv4.method manual ipv4.addresses 192.168.10.5/24 ipv4.gateway 192.168.10.1

Modify an existing profile (e.g., set DNS and auto-connect):

nmcli con mod "Corp-LAN" ipv4.dns "8.8.8.8" connection.autoconnect yes

Activate the profile:

nmcli con up "Corp-LAN"

Deactivate the profile:

nmcli con down "Corp-LAN"

Reload configurations from disk:

nmcli con reload

Rename a profile:

nmcli con mod "Corp-LAN" connection.id "Office-Main"

Change the interface bound to a profile:

nmcli con mod "Office-Main" connection.interface-name ens192

Warning: Modifying the active management interface remotely risks loss of connectivity. Always test changes on console access or secondary interfaces when possible.