For system administrators, their daily work revolves around the configuration (configuration), maintenance, troubleshooting, monitoring, protection, and management of servers in the data center. This guide answers questions about how to manage Ubuntu / Debian network interfaces using some default tools. Network administrator It is a tool designed to manage the network on the machine. It has many tools that can be used to manage the network configuration on all Linux distributions. This tool is the default network management tool on Ubuntu systems. It provides the following network management tools:
- Nmtui – This tool runs on a Linux terminal window. It is a text-based network manager tool that can be changed on the network by entering data and menu selections. It is used to perform basic network management tasks, and it has many missing features available in NMCLI.
- Gnome settings – From the Gnome desktop, you can use the Gnome web application to manage the network. It provides basic network management and is easy to perform configuration.
- Nano Connect Editor -This is a graph-based network manager tool that allows access to NetworkManager configuration options
- NMCLI – normally called as Network command line interface Is a network tool used to manage NetworkManager and display the status of network connections.It is useful when you cannot access a graphical environment or run a server version and make network configuration changes
The network manager is preferred due to the following features:
- Flexible network visualization
- Comprehensive network management
- Built-in root cause analysis function
- Fully customizable content
- Built-in device and interface polling function
- Click Network Troubleshooting
- Extensive reporting functions
- Multiple integration options
- Growing network discovery
At the end of this guide, you should be able to install and use NetworkManager NMCLI On Ubuntu / Debian system.
prerequisites
For this guide, please make sure that your Ubuntu|Debian system is updated and upgraded as follows.
sudo apt-get update && sudo apt-get upgrade
Step 1-Install NetworkManager on Ubuntu|Debian system
By default, NetworkManager exists on the Ubuntu|Debian system, but if you need to install it, I will demonstrate two methods to install NetworkManager on your Ubuntu|Debian system.
- Use APT
- Use snap
1a) Use APT to install NetworkManager on Ubuntu|Debian system
NetworkManager is available in the APT repository of the default ubuntu|Debian system and can be installed as follows.
sudo apt-get install network-manager
Start and enable the network manager as shown below.
sudo systemctl start NetworkManager.service
sudo systemctl enable NetworkManager.service
1b) Use Snap to install NetworkManager on Ubuntu|Debian system.
NetworkManager can also be found in the Snap store and can be installed on Ubuntu|Debian systems Break off Installation and activation are as follows.
sudo apt install snapd
sudo systemctl enable --now snapd.socket
sudo ln -s /var/lib/snapd/snap /snap
Then install NetworkManager using the following command:
snap install network-manager
After the installation is complete, all required plugs and sockets will be automatically connected, as verified below.
snap connections network-manager
Sample output:
Interface
Plug
Slot
Notes
dbus network-manager:wpa - -
firewall-control network-manager:firewall-control :firewall-control -
hardware-observe network-manager:hardware-observe :hardware-observe -
login-session-observe network-manager:login-session-observe :login-session-observe -
modem-manager network-manager:modem-manager :modem-manager -
network network-manager:network :network -
network-manager - network-manager:service -
network-manager network-manager:nmcli - -
network-observe network-manager:network-observe :network-observe -
network-setup-control network-manager:network-setup-control :network-setup-control -
network-setup-observe network-manager:network-setup-observe :network-setup-observe -
ppp network-manager:ppp :ppp -
After the installation is complete, the network manager will automatically start and run in the background, use the command to check its status:
$ sudo systemctl status NetworkManager.service
● NetworkManager.service - Network Manager
Loaded: loaded (/lib/systemd/system/NetworkManager.service; enabled; vendor preset: enabled)
Active:
active (running)
since Tue 2021-09-28 14:50:00 EAT; 1min ago
Docs: man:NetworkManager(8)
Main PID: 423 (NetworkManager)
Tasks: 3 (limit: 2404)
Memory: 13.6M
CPU: 303ms
CGroup: /system.slice/NetworkManager.service
└─423 /usr/sbin/NetworkManager --no-daemon
Sep 28 14:50:16 debian NetworkManager[423]: <info> [1632829816.7357] manager: NetworkManager state is now CONNECTED_LOCAL
Sep 28 14:50:16 debian NetworkManager[423]: <info> [1632829816.7434] manager: NetworkManager state is now CONNECTED_SITE
Sep 28 14:50:16 debian NetworkManager[423]: <info> [1632829816.7468] policy: set 'Wired connection 1' (enp0s3) as default for IPv4 routing and DNS
Step 2-Use NetworkManager NMCLI on Ubuntu|Debian system.
NMCLI is a network utility tool that allows us to manage the network configuration. There are several commands that can be used to manage the network.
Modify network connection
Using NMCLI to modify the network connection requires us to start by listing the network connection, using the command:
nmcli connection show
Sample output:
AME UUID TYPE DEVICE
Wired connection 1 ac98eab7-1ad3-4cf0-93a0-210bfe3bb7e2 ethernet enp0s3
Show active connections
The above command shows all connections, but if you want to see active or upward connections, you will add --active Mark the above command;
nmcli connection show --active
Sample output:
NAME UUID TYPE DEVICE
Wired connection 1 ac98eab7-1ad3-4cf0-93a0-210bfe3bb7e2 ethernet enp0s3
Using the connection profile name, you can view the following additional information.
nmcli connection show "Wired connection 1"
Sample output:
Use NMCLI to add and modify network connections
Use NMCLI to add a network connection
Using NMCLI, you can use the following syntax to add a new connection to the Ubuntu|Debian system.
sudo nmcli connection add type <network-type> ifname <connection-name>
Use NMCLI to modify an existing network connection
Using NMCLI, the following syntax can be used to adjust and configure existing network connections, such as switching between static and DHCP configuration.
sudo nmcli connection modify <
connection-id
> <
parameter
> <
value
>
Now let’s see what configuration we can do Add to with Adjustment Connect using NMCLI. We will first add a NetworkManager connection profile for our connection.For me, it is an Ethernet connection, I will add a connection profile named My new connection
nmcli connection add con-name
My-New-Connection
ifname
enp0s3
type
ethernet
Sample output:
Connection 'My-New-Connection' (a6b26540-4c06-4a80-a0fa-a2868e4006e5) successfully added.
After adding the connection profile, we will make the following adjustments. Please remember to use a syntax similar to the one I gave to set your own IP address, gateway, DNS server, etc.
To set up automatic startup of the network connection, use:
nmcli connection modify
My-New-Connection
connection.autoconnect yes
1. Set a static IPv4 address, the subnet mask is /24
for example, We modify the existing connection to a static IP_Address and change the subnet /twenty four Without this specification, it will assign an IP with a default mask, which may cause problems in the future.
sudo nmcli connection modify
My-New-Connection
ipv4.address 192.168.100.157/24
2 . Use /64 subnet mask to set a static IPv6 address
nmcli connection modify
My-New-Connection
ipv6.addresses 2001:db8:1::1/64
3. Set IPv4/IPv6 default gateway
##For IPv4
nmcli connection modify
My-New-Connection
ipv4.gateway 192.168.100.1
##For IPv6
nmcli connection modify
My-New-Connection
ipv6.gateway 2001:db8:1::fffe
4 . Set up IPv4/IPv6 DNS server
##For IPv4
nmcli connection modify
My-New-Connection
ipv4.dns "192.168.100.200"
##For IPv6
nmcli connection modify
My-New-Connection
ipv6.dns "2001:db8:1::ffbb"
5. Set the IPv4 and IPv6 connection mode to automatic
##For IPv4
nmcli connection modify
My-New-Connection
ipv4.method
auto
##For IPv6
nmcli connection modify
My-New-Connection
ipv6.method
auto
For the changes to take effect, you need to activate the configuration file.
$ nmcli connection up
My-New-Connection
connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)
Now check the active connection.
nmcli connection show --active
Verify the set IP_Address.
hostname -I
192.168.100.120
192.168.100.157
From the output, I have two IP addresses, one primary IP and one Minor intellectual property Added by the new connection profile My-New-Connection.you can use it ip a The command is as follows. 
Use NMCLI to manage devices
The NMCLI utility can also be used to manage devices, such as:
Display device status
sudo nmcli -p dev status
Sample output: 
Modify device configuration
Before modifying the device configuration, you first need to obtain the device information.
sudo nmcli device show
Sample output: 
With the device information, you can use the following syntax to modify the device settings.
$ sudo nmcli device modify <interface-name> <parameter> <value>
###OR
$ sudo nmcli dev mod <interface-name> <parameter> <value>
Please keep in mind that the above changes are temporary and can be reset to the default settings with the following command:
sudo nmcli dev reapply interface-name
If you encounter problems when using NMCLI Device Manager, please use the following command to find help:
sudo nmcli device help
in conclusion.
now it’s right! We have learned how to install and use NetworkManager NMCLI on Ubuntu / Debian systems. I hope this guide is important to you. I assume you can now use NetworkManager NMCLI to manage your network connections and network devices.
see more:
- How to create an internal network in Xen | XCP-ng
- Add secondary IP address to CentOS / RHEL network interface
- Configure BIND slave DNS server on Debian