Netplan Basics¶

Configuration Files¶

Location¶

Netplan configuration files are stored in:

/etc/netplan/
├── 00-installer-config.yaml    # Created by Ubuntu installer
├── 01-netcfg.yaml              # Custom configuration
└── 99-custom.yaml              # Override file

Processing Order¶

Files are processed in lexicographical order: - 00-* files process first - 99-* files process last - Later files can override earlier settings

Naming Convention¶

/etc/netplan/
├── 00-installer-config.yaml    # Base from installer
├── 50-cloud-init.yaml          # Cloud-init generated
├── 60-bridge.yaml              # Custom bridge config
└── 90-local.yaml               # Local overrides

Basic Structure¶

Minimal Configuration¶

network:
  version: 2
  renderer: networkd
  ethernets:
    eth0:
      dhcp4: true

Structure Breakdown¶

network:                    # Root key (required)
  version: 2                # Schema version (required)
  renderer: networkd        # Backend (optional, has default)

  ethernets:                # Ethernet devices
    eth0:                   # Interface name or match pattern
      dhcp4: true           # Configuration options

  bridges:                  # Bridge devices
    br0:
      interfaces: [eth0]

  bonds:                    # Bond devices
    bond0:
      interfaces: [eth0, eth1]

  vlans:                    # VLAN devices
    vlan100:
      id: 100
      link: eth0

  wifis:                    # Wireless devices
    wlan0:
      access-points:
        "MyNetwork":
          password: "secret"

Commands¶

netplan generate¶

Generates backend configuration without applying:

sudo netplan generate

# Files created in:
# /run/systemd/network/   (for networkd)
# /run/NetworkManager/    (for NetworkManager)

netplan apply¶

Applies configuration immediately:

sudo netplan apply

Remote Access Risk

netplan apply can disconnect you if configuration is wrong. Use netplan try for remote administration.

netplan try¶

Applies configuration with automatic rollback:

# Default 120 second timeout
sudo netplan try

# Custom timeout
sudo netplan try --timeout 60

Press ENTER to confirm changes. If you don't (or can't because you lost connectivity), configuration reverts automatically.

netplan get¶

Show current configuration:

# All configuration
sudo netplan get

# Specific interface
sudo netplan get ethernets.eth0

# Output as YAML
sudo netplan get --root-dir=/

netplan set¶

Modify configuration from command line:

# Set DHCP
sudo netplan set ethernets.eth0.dhcp4=true

# Set static IP
sudo netplan set ethernets.eth0.addresses='[192.168.1.100/24]'

# Then apply
sudo netplan apply

netplan status¶

Show current network status (Ubuntu 23.04+):

sudo netplan status
sudo netplan status eth0

netplan info¶

Show Netplan version and features:

netplan info

Interface Identification¶

By Name¶

Direct interface name:

ethernets:
  enp5s0:
    dhcp4: true

By Match¶

Match multiple interfaces:

ethernets:
  ethernet-dhcp:
    match:
      driver: e1000
    dhcp4: true

Match Options¶

ethernets:
  matched:
    match:
      name: "enp*"           # Glob pattern
      macaddress: "aa:bb:cc:dd:ee:ff"
      driver: "virtio*"
    set-name: eth0           # Rename matched interface

Common Interface Names¶

Predictable Names (Default)¶

Pattern	Meaning
`enp5s0`	Ethernet, PCI bus 5, slot 0
`ens3`	Ethernet, slot 3
`eno1`	Onboard Ethernet 1
`enx...`	Ethernet by MAC address
`wlp2s0`	Wireless, PCI bus 2, slot 0

Finding Your Interface¶

# List all interfaces
ip link show

# Show detailed info
networkctl list

# Show status
networkctl status enp5s0

Configuration Validation¶

Syntax Check¶

# Check YAML syntax
sudo netplan generate

# Debug output
sudo netplan --debug generate

Common Errors¶

Invalid YAML:

# WRONG - tabs instead of spaces
network:
    version: 2    # Tab character!

# CORRECT - spaces only
network:
  version: 2      # Two spaces

Missing Required Fields:

# WRONG - missing version
network:
  ethernets:
    eth0:
      dhcp4: true

# CORRECT
network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true

Invalid IP Format:

# WRONG - missing CIDR notation
addresses:
  - 192.168.1.100

# CORRECT
addresses:
  - 192.168.1.100/24

Backend Files¶

systemd-networkd Files¶

Generated in /run/systemd/network/:

ls -la /run/systemd/network/

# Example files:
# 10-netplan-eth0.network
# 10-netplan-br0.netdev
# 10-netplan-br0.network

NetworkManager Files¶

Generated in /run/NetworkManager/system-connections/:

ls -la /run/NetworkManager/system-connections/

Persistence¶

Configuration Persistence¶

YAML files in /etc/netplan/ persist across reboots
Generated files in /run/ are recreated at boot

When Changes Take Effect¶

Action	Effect
Edit YAML	No immediate effect
`netplan generate`	Creates backend files
`netplan apply`	Applies to running system
Reboot	Re-generates and applies

Minimal vs Full Configuration¶

Minimal (DHCP)¶

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true

Complete (Static)¶

network:
  version: 2
  renderer: networkd

  ethernets:
    eth0:
      addresses:
        - 192.168.1.100/24
        - 192.168.1.101/24
      routes:
        - to: default
          via: 192.168.1.1
        - to: 10.0.0.0/8
          via: 192.168.1.254
      nameservers:
        search: [example.com, local]
        addresses: [192.168.1.1, 1.1.1.1]
      mtu: 1500
      optional: false