====== 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.

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===== 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**.

<WRAP info>
**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.

</WRAP>

----

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

<code bash>
ip a
</code>

returns:

<code bash>
...
enp3s0
...
</code>

<WRAP info>
**NOTE:**  Note the interface name that you want to configure using Netplan.

  * In this case, **enp3s0**.
</WRAP>


----

Edit the netplan file.

<file yaml /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
</file>

<WRAP info>
**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.

</WRAP>

----

===== Test =====

Before applying any changes, test the configuration file:

<code bash>
sudo netplan try
</code>

----

===== Apply Configuration =====

<code bash>
sudo netplan apply
</code>

<WRAP info>
**NOTE:**  In case you see any error, try debugging to investigate the problem.

To run debug:

<code bash>
sudo netplan –d apply
</code>

</WRAP>

----

===== Restart the network service =====

==== On Ubuntu Desktop ====

<code bash>
sudo systemctl restart network-manager
</code>

==== On Ubuntu Server ====

<code bash>
sudo systemctl restart system-networkd
</code>

----

===== Verify IP Address =====

<code bash>
ip a
</code>

----