Systemd/systemd-networkd

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Not to be confused with systemd.

Not to be confused with systemd/systemd-resolved.

systemd-networkd provides simple configuration of wired network interfaces. It is disabled by default on Gentoo systems, but can be quickly enabled as necessary enable connectivity.

Configuration

To configure systemd-networkd, create a .network file under the /etc/systemd/network directory. Files are written in INI style syntax. See the systemd.network(5) man page for reference.

DHCP

A simple DHCP configuration is given below:

FILE /etc/systemd/network/50-dhcp.network

[Match]
Name=en*
 
[Network]
DHCP=yes

Static IP address

Wired connection with static IP address (uses CIDR notation for subnetting):

FILE /etc/systemd/network/50-static.network

[Match]
Name=enp1s0
 
[Network]
Address=192.168.1.10/24
Gateway=192.168.1.1
DNS=192.168.1.1

Wireless card

A simple DHCP configuration for the wireless card wlan0 is given below:

FILE /etc/systemd/network/50-wireless.network

[Match]
Name=wlan0
 
[Network]
DHCP=yes
IgnoreCarrierLoss=3s

Connecting to a wireless access point can be achieved using Iwd or Wpa supplicant.

DNS (systemd-resolved)

Note that systemd-networkd does not update the resolv.conf file or provide DNS service by default. See the systemd/systemd-resolved article for details on how to setup address name resolution (DNS) on systemd systems.

Usage

Service

To enable and start the service now:

root #systemctl enable --now systemd-networkd.service

networkctl

A networkctl user space utility exists to query and control the networking subsystem for systems running systemd-networkd.

user $networkctl --help

networkctl [OPTIONS...] COMMAND

Query and control the networking subsystem.

Commands:
  list [PATTERN...]      List links
  status [PATTERN...]    Show link status
  lldp [PATTERN...]      Show LLDP neighbors
  label                  Show current address label entries in the kernel
  delete DEVICES...      Delete virtual netdevs
  up DEVICES...          Bring devices up
  down DEVICES...        Bring devices down
  renew DEVICES...       Renew dynamic configurations
  forcerenew DEVICES...  Trigger DHCP reconfiguration of all connected clients
  reconfigure DEVICES... Reconfigure interfaces
  reload                 Reload .network and .netdev files

Options:
  -h --help              Show this help
     --version           Show package version
     --no-pager          Do not pipe output into a pager
     --no-legend         Do not show the headers and footers
  -a --all               Show status for all links
  -s --stats             Show detailed link statistics
  -l --full              Do not ellipsize output
  -n --lines=INTEGER     Number of journal entries to show
     --json=pretty|short|off
                         Generate JSON output

See the networkctl(1) man page for details.

Troubleshooting

Hangs

Users may encounter a situation where the built-in systemd-networkd-wait-online service may try to confirm network connectivity for all links it is aware of and which are managed by systemd-networkd, but there aren't any configured by the system administrator. This will result in the default two-minute timeout to occur, preventing any depending service from accessing the network. The following examples of problems may follow:

• A Samba share failing to automount on boot
• A WireGuard interface failing being brought up on boot

The list of affected services can be obtained via

root #systemctl list-dependencies systemd-networkd-wait-online.service --all --reverse

The system administrator can use several approaches to fix any such problem.

If a specific network interface is known to be required for network connectivity (e.g., eth0), run

root #systemctl disable systemd-networkd-wait-online.service

root #systemctl enable systemd-networkd-wait-online@eth0.service

Alternatively, create an override for the service via

root #systemctl edit systemd-networkd-wait-online.service

and add the lines

FILE /etc/systemd/system/systemd-networkd-wait-online.service.d/override.conf

[Match]
[Service]
ExecStart=
ExecStart=/usr/lib/systemd/systemd-networkd-wait-online --interface=eth0

where the first ExecStart= clears any existing entries, and eth0 should be replaced with name of the interface that is primary/relevant for the behavior that is desired. One could also write

FILE /etc/systemd/system/systemd-networkd-wait-online.service.d/override.conf

[Match]
[Service]
ExecStart=
ExecStart=/usr/lib/systemd/systemd-networkd-wait-online --interface=any

to accept connectivity with any interface, or

FILE /etc/systemd/system/systemd-networkd-wait-online.service.d/override.conf

[Match]
[Service]
ExecStart=
ExecStart=/usr/lib/systemd/systemd-networkd-wait-online --ignore=eth0

to ignore a particular one.

See also

• systemd/systemd-resolved — a address name resolution (DNS) daemon which can be used in conjunction with systemd-networkd.
• systemd — a modern SysV-style init and rc replacement for Linux systems.
• Network management — describes possibilities for managing the network stack.

External resources

• systemd.network — Network configuration