how to configure network with nmcli command in Linux

nmcli is a command-line client for NetworkManager, which is a system network service that manages network devices and connections, primarily for Linux-based operating systems.

nmcli provides a way to display network status, manage network connections, and control the NetworkManager daemon, all from the command line.

Here’s a brief overview of nmcli and how to use it:

General Syntax

nmcli [OPTIONS] OBJECT { COMMAND | help }

• OPTIONS: Global options for nmcli (e.g., -p for pretty output).
• OBJECT: The type of object you want to manage (e.g., connection, device).
• COMMAND: The action you want to perform on the object.

 

A “device” refers to a network interface on your system. This can be an Ethernet interface, a Wi-Fi interface, a Bluetooth interface, a VPN virtual interface, and more.

The term “connection” refers to a set of configuration settings that describe how to connect to a network. Essentially, a connection is a named profile that contains all the details needed to connect to a specific network.

Each connection has:

• A unique name.
• A type (e.g., Wi-Fi, Ethernet, VPN, bridge, etc.).
• Various settings appropriate for that type. For instance, a Wi-Fi connection would have SSID, security type, and password, while an Ethernet connection might have details about IP configuration (static or DHCP).

 

Common Usages

Display General Status:

nmcli general status

List All Network Devices:

nmcli device

Show Details of a Specific Device:
Replace devicename with the name of your device (e.g., eth0, wlan0).

nmcli device show devicename

List All Network Connections:

nmcli connection show

Activate/Deactivate a Connection:
Replace connectionname with the name of the connection you want to activate or deactivate.

nmcli connection up connectionname
nmcli connection down connectionname

Add a New Connection:
For example, to add a new Wi-Fi connection:

nmcli connection add con-name "MyWiFi" type wifi ifname wlan0 ssid "SSID_NAME"

Delete a Connection:
Replace connectionname with the name of the connection you want to delete.

nmcli connection delete connectionname

Modify a Connection:
For example, to change the IPv4 method of a connection to manual and set an IP address:

nmcli connection modify connectionname ipv4.method manual ipv4.addresses "192.168.1.10/24"

3. Tips:

Help Command: If you’re unsure about how to use a specific command, you can always append help to get more information. For example:

nmcli device help

Remember, while nmcli is a powerful tool, making changes to your network settings can disrupt your connection. Always double-check commands, especially when modifying or deleting connections.

configure network in Linux with nmcli command

Configuring a network using the nmcli command in Linux involves a series of steps. Below is a basic guide on how to do this for a wired (ethernet) and wireless (Wi-Fi) connection.

 Wired (Ethernet) Connection:
a. List Available Devices:

nmcli device

b. Add a New Connection:
Replace eth0 with your device name, and my-ethernet with your desired connection name.

nmcli connection add type ethernet con-name my-ethernet ifname eth0

c. Set Static IP (Optional):

If you want to set a static IP, netmask, and gateway:

nmcli connection modify my-ethernet ipv4.addresses "192.168.1.10/24" ipv4.gateway "192.168.1.1" ipv4.method manual

d. Set DNS (Optional):

nmcli connection modify my-ethernet ipv4.dns "8.8.8.8,8.8.4.4"

e. Activate the Connection:

nmcli connection up my-ethernet

create bonding with nmcli command

Bonding is a method of aggregating multiple network interfaces into a single logical “bonded” interface, typically to provide redundancy or increased throughput. Using `nmcli`, you can easily set up bonding in Linux.

Here’s a step-by-step guide on how to create a bond using nmcli:

1. Install Necessary Packages:
First, ensure that the NetworkManager package is installed and running.

sudo apt install network-manager

2. Create the Bond:
Use the following command to create a bond. In this example, the bond is named bond0 and uses the mode 802.3ad (LACP).

nmcli con add type bond con-name bond0 ifname bond0 mode 802.3ad primary eth0

3. Add Slave Interfaces to the Bond:
Now, add the required Ethernet interfaces to the bond. In this example, eth0 and eth1 are added as slaves to bond0.

nmcli con add type ethernet con-name bond0-slave1 ifname eth0 master bond0
nmcli con add type ethernet con-name bond0-slave2 ifname eth1 master bond0

4. Configure IP Details for the Bond:
You can assign an IP address to the bonded interface like so:

nmcli con mod bond0 ipv4.addresses "192.168.1.10/24" ipv4.gateway "192.168.1.1" ipv4.method manual

5. Activate the Bond:
Bring up the bond and its slave interfaces:

nmcli con up bond0
nmcli con up bond0-slave1
nmcli con up bond0-slave2

6. Verify the Bond Configuration:
To check the status of the bond and its slaves:

nmcli con show
nmcli -p con show bond0
cat /proc/net/bonding/bond0

7. Optional Settings:
There are several bonding options that you can configure depending on your needs, such as setting the bonding mode (balance-rr, active-backup, 802.3ad, etc.), configuring ARP monitoring, and setting the bonding interval. For example, to change the bonding mode:

nmcli con mod bond0 bond.options "mode=active-backup"

Note: Always refer to the official documentation or the nmcli man page for a comprehensive list of options and capabilities. Also, make sure that your switch or router supports the bonding mode you’re using (especially for modes like 802.3ad).