List multiple connections with the same name using nmcli NetworkManager under CentOS

When using the NetworkManager it is possible to create multiple connections with the same name, which may result in confusion how to list them all and how to delete the unneeded ones.

main menu
List network connections

It is simple to create a connection with a certain name, activate it and then deactivate it:

[root@srv ~]# nmcli con add type ethernet con-name eno2 ifname eno2 ipv4.method manual ipv4.addresses
Warning: There are 3 other connections with the name 'eno2'. Reference the connection by its uuid '47488136-83bf-4394-b2aa-3123886ca9a5'
Connection 'eno2' (47488136-83bf-4394-b2aa-3123886ca9a5) successfully added.
[root@srv ~]# nmcli con down eno2
Connection 'eno2' successfully deactivated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/6)

So after deactivating the “eno2” connection (the real network interface is with the same name) it is possible to create another connection with the name “eno2” using the same (or even other network interface).
If there are multiple connections with the same name, when creating a new one, there is a warning as it is shown above. There is also a line in the nmcli output, which indicates how many connections there are with this name:

[root@srv ~]# nmcli
br0: connected to br0
        bridge, AC:1F:6B:F6:F6:3C, sw, mtu 1500
        ip4 default
        route4 default via metric 425
        route4 metric 425
        inet6 fe80::c1d5:b200:7259:7e4d/64
        route6 fe80::/64 metric 1024

eno1: connected to bridge-slave-eno1
        "Intel I210"
        ethernet (igb), AC:1F:6B:F6:F6:3C, hw, mtu 1500
        master br0

eno2: disconnected
        "Intel I210"
        3 connections available
        ethernet (igb), AC:1F:6B:F6:F6:3D, hw, mtu 1500

lo: unmanaged
        loopback (unknown), 00:00:00:00:00:00, sw, mtu 65536

DNS configuration:
        interface: br0

Use "nmcli device show" to get complete information about known devices and
"nmcli connection show" to get an overview on active connection profiles.

Consult nmcli(1) and nmcli-examples(7) manual pages for complete usage details.

Under the disconnected connection name “eno2”, there is a line informing there are 3 connections available under this section.

To list all network connections use the short syntax, which will show all the connections identified by their unique identifier (UUID):

main menu
3 connections with the same name

Keep on reading!

Replace current interface configuration with a bridge device using nmcli (NetworkManager)

This article shows how the primary network interface could be replaced by a bridge device and the network interface becomes a part of the bridge as a slave device without reboot or restart of the server. Using nmcli under CentOS 8 (and probably any other Linux distribution like Ubuntu, which uses NetworkManager to configure network devices).
The main steps are:

  1. Create a connection profile of a bridge device.
  2. Set the same network configuration as the primary network to the bridge device.
  3. Create a connection profile for the primary interface device as a slave network device to the newly created bridge.
  4. Delete the current primary connection, which is using the primary network device and configuration.
  5. Reload the bridge connection profile to take effect. The bridge device will actually begin to work.

The main goal is not to reboot the server or lose the connection to the server. The primary network interface is the only connection on the server and losing it the server is going to be unreachable. So the last two steps should be performed in the background or a script or a detached terminal (like screen).
Here are all the commands in one place:

nmcli connection add type bridge ifname br0 con-name br0 ipv4.method manual ipv4.addresses "" ipv4.gateway "" ipv4.dns ""
nmcli con add type bridge-slave ifname enp0s3 master br0
nmcli con del "enp0s3"; nmcli con reload "br0" &

Here is the detailed information for the above commands:
Keep on reading!