Skip to content

Ethernet Configuration

Basic Configuration

DHCP (Dynamic IP)

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

Static IP

network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses:
          - 1.1.1.1
          - 8.8.8.8

Dual Stack (IPv4 + IPv6)

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      dhcp6: true

Static Dual Stack

network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - 192.168.1.100/24
        - "2001:db8::100/64"
      routes:
        - to: default
          via: 192.168.1.1
        - to: default
          via: "2001:db8::1"
      nameservers:
        addresses:
          - 1.1.1.1
          - "2001:4860:4860::8888"

Interface Identification

By Device Name

Most common, uses predictable naming:

ethernets:
  enp5s0:           # PCI bus 5, slot 0
    dhcp4: true

  eno1:             # Onboard port 1
    dhcp4: true

  ens192:           # VMware interface
    dhcp4: true

By MAC Address

Identify specific hardware:

ethernets:
  server-nic:
    match:
      macaddress: "aa:bb:cc:dd:ee:ff"
    dhcp4: true

By Driver

Match all interfaces using a driver:

ethernets:
  intel-nics:
    match:
      driver: "e1000*"
    dhcp4: true

Rename Interface

ethernets:
  main:
    match:
      macaddress: "aa:bb:cc:dd:ee:ff"
    set-name: eth0       # Rename to eth0
    dhcp4: true

Multiple Addresses

Primary and Secondary

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24    # Primary
      - 192.168.1.101/24    # Secondary
      - 192.168.1.102/24    # Another secondary

Different Subnets

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24
      - 10.0.0.100/24
    routes:
      - to: default
        via: 192.168.1.1

With Labels

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24:
          label: "eth0:0"
      - 192.168.1.101/24:
          label: "eth0:1"

DHCP Options

Basic DHCP Customization

ethernets:
  eth0:
    dhcp4: true
    dhcp4-overrides:
      use-dns: true         # Use DHCP DNS
      use-ntp: true         # Use DHCP NTP
      use-hostname: true    # Set hostname from DHCP
      use-mtu: true         # Use DHCP MTU
      use-routes: true      # Use DHCP routes
      use-domains: true     # Use DHCP search domains
      send-hostname: true   # Send hostname to server

Route Metric

Control route priority:

ethernets:
  eth0:
    dhcp4: true
    dhcp4-overrides:
      route-metric: 100      # Lower = higher priority

  eth1:
    dhcp4: true
    dhcp4-overrides:
      route-metric: 200      # Backup route

Custom Hostname

ethernets:
  eth0:
    dhcp4: true
    dhcp4-overrides:
      send-hostname: true
      hostname: myserver     # Send this hostname

Ignore DHCP Options

ethernets:
  eth0:
    dhcp4: true
    dhcp4-overrides:
      use-dns: false        # Use static DNS instead
      use-routes: false     # Use static routes instead
    nameservers:
      addresses: [1.1.1.1]
    routes:
      - to: default
        via: 192.168.1.1

DNS Configuration

Static DNS Servers

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24
    nameservers:
      addresses:
        - 192.168.1.1       # Local
        - 1.1.1.1           # Cloudflare
        - 8.8.8.8           # Google

Search Domains

ethernets:
  eth0:
    dhcp4: true
    nameservers:
      search:
        - example.com
        - internal.example.com
      addresses:
        - 192.168.1.1

DHCP with DNS Override

ethernets:
  eth0:
    dhcp4: true
    dhcp4-overrides:
      use-dns: false        # Ignore DHCP DNS
    nameservers:
      addresses:
        - 1.1.1.1           # Use Cloudflare instead

Routing

Default Gateway

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24
    routes:
      - to: default
        via: 192.168.1.1

Multiple Routes

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24
    routes:
      - to: default
        via: 192.168.1.1
      - to: 10.0.0.0/8
        via: 192.168.1.254
      - to: 172.16.0.0/12
        via: 192.168.1.253

Route Options

ethernets:
  eth0:
    addresses:
      - 192.168.1.100/24
    routes:
      - to: 10.0.0.0/8
        via: 192.168.1.254
        metric: 100          # Priority
        on-link: true        # Gateway is on-link
        table: 100           # Routing table

MTU

ethernets:
  eth0:
    dhcp4: true
    mtu: 1500            # Standard

  eth1:
    dhcp4: true
    mtu: 9000            # Jumbo frames

MAC Address Override

ethernets:
  eth0:
    macaddress: "aa:bb:cc:dd:ee:ff"
    dhcp4: true

Wake-on-LAN

ethernets:
  eth0:
    wakeonlan: true
    dhcp4: true

ethernets:
  eth0:
    dhcp4: true
    link-local: [ipv4, ipv6]   # Enable both

  eth1:
    dhcp4: true
    link-local: []              # Disable link-local

Boot Behavior

Optional Interface

Don't wait for this interface at boot:

ethernets:
  eth0:
    dhcp4: true
    optional: true       # Boot continues without this

Critical Interface

Default behavior - wait for interface:

ethernets:
  eth0:
    dhcp4: true
    optional: false      # Wait for this (default)

Activation Mode

ethernets:
  eth0:
    dhcp4: true
    activation-mode: manual  # Don't auto-bring-up

Hardware Settings

Offloading

ethernets:
  eth0:
    dhcp4: true
    receive-checksum-offload: true
    transmit-checksum-offload: true
    tcp-segmentation-offload: true
    generic-segmentation-offload: true
    generic-receive-offload: true
    large-receive-offload: true

Ring Buffers

ethernets:
  eth0:
    dhcp4: true
    ring:
      rx: 4096
      tx: 4096

Multiple NICs

Different Roles

network:
  version: 2
  ethernets:
    # Management network
    eno1:
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        addresses: [192.168.1.1]

    # Storage network
    enp5s0:
      addresses:
        - 10.0.0.100/24
      mtu: 9000
      routes:
        - to: 10.0.0.0/8
          via: 10.0.0.1

    # VM network (no IP on host)
    enp6s0:
      dhcp4: false
      dhcp6: false

Failover with Metrics

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      dhcp4-overrides:
        route-metric: 100      # Primary

    eth1:
      dhcp4: true
      dhcp4-overrides:
        route-metric: 200      # Failover

Server Examples

Basic Server

network:
  version: 2
  renderer: networkd
  ethernets:
    enp5s0:
      addresses:
        - 192.168.1.100/24
      routes:
        - to: default
          via: 192.168.1.1
      nameservers:
        search: [home.local]
        addresses: [192.168.1.1, 1.1.1.1]

Multi-Homed Server

network:
  version: 2
  renderer: networkd
  ethernets:
    # Public interface
    enp1s0:
      addresses:
        - 203.0.113.100/24
      routes:
        - to: default
          via: 203.0.113.1
      nameservers:
        addresses: [1.1.1.1]

    # Private interface
    enp2s0:
      addresses:
        - 10.0.0.100/24
      routes:
        - to: 10.0.0.0/8
          via: 10.0.0.1
          metric: 100

DHCP Fallback to Static

network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      addresses:
        - 192.168.1.100/24    # Used if DHCP fails