Ubuntu - Networking - Netplan - Configure networking with Netplan

Netplan is based on YAML based configuration system that makes configuration process very simple.

Netplan has replaced the old configuration file /etc/network/interfaces that we previously used for configuring network interfaces in Ubuntu.

Configuration Files

Netplan configuration files are at /etc/netplan/*.yaml.

Ubuntu server defaults to using system-networkd with the configuration file named 01-netcfg.yaml,
Ubuntu desktop generates a configuration file for Network-Manager named 01-network-manager-all.yaml.

NOTE: If you have multiple interfaces, use 02-network-manager-all.yaml for the second interface.

Netplan applies the configuration in the numerical order; i.e. the 01 file will be applied before the 02 file.

Find the name of the active network interfaces that you want to configure

ip a

returns:

...
enp3s0
...

NOTE: Note the interface name that you want to configure using Netplan.

In this case, enp3s0.

Edit the netplan file.

/etc/netplan/01-network-manager-all.yaml

# Let NetworkManager manage all devices on this system
#network:
#  version: 2
#  renderer: NetworkManager

network:
  version: 2
  #renderer: NetworkManager
  renderer: networkd
  ethernets:
    enp3s0:
      dhcp4: no
      # disable existing configuration for ethernet
      #addresses: [192.168.1.69/24]
      #gateway4: 192.168.1.1
      #nameservers:
        #addresses: [192.168.1.1]
      dhcp6: no
 
  # add configuration for bridge interface
  bridges:
    br0:
      interfaces: [enp3s0]
      dhcp4: no
      addresses: [192.168.1.69/24]
      gateway4: 192.168.1.1
      nameservers:
        addresses: [192.168.1.1]
        #addresses: [192.168.1.26,192.168.1.2,192.168.1.25,192.168.1.1,1.1.1.1]
      parameters:
        # stp: false
        stp: true
        forward-delay: 4
      dhcp6: no

NOTE:

renderer: Either networkd or NetworkManager.
- networkd uses the settings in the Netplan config file. This is preferred.
- NetworkManager uses the settings in the Ubuntu Network GUI settings.

stp: Defines whether the bridge should use Spanning Tree Protocol
forward-delay: Specifies the period of time the bridge will remain in the Listening and Learning states before getting to the Forwarding state.

Test

Before applying any changes, test the configuration file:

sudo netplan try

Apply Configuration

sudo netplan apply

NOTE: In case you see any error, try debugging to investigate the problem.

To run debug:

sudo netplan –d apply

Restart the network service

On Ubuntu Desktop

sudo systemctl restart network-manager

On Ubuntu Server

sudo systemctl restart system-networkd

Verify IP Address

ip a

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