Editing Linux router with WAN, LAN and DMZ (section)

== Interfaces with systemd-networkd ==
One file per interface in <code>/etc/systemd/network/</code>. The numeric prefix
only controls the order the files are read.

WAN — <code>/etc/systemd/network/10-wan.network</code>:
<syntaxhighlight lang="ini">
[Match]
Name=eth0

[Network]
DHCP=ipv4
# Static instead? Drop DHCP= and use:
# Address=203.0.113.10/24
# Gateway=203.0.113.1
# DNS=1.1.1.1

[DHCPv4]
UseDNS=yes
UseNTP=yes
</syntaxhighlight>

LAN — <code>/etc/systemd/network/20-lan.network</code>:
<syntaxhighlight lang="ini">
[Match]
Name=eth1

[Network]
Address=10.0.1.1/24
ConfigureWithoutCarrier=yes
</syntaxhighlight>

DMZ — <code>/etc/systemd/network/30-dmz.network</code>:
<syntaxhighlight lang="ini">
[Match]
Name=eth2

[Network]
Address=10.0.0.1/24
ConfigureWithoutCarrier=yes
</syntaxhighlight>

Apply and inspect:
<syntaxhighlight lang="bash">
systemctl enable --now systemd-networkd
networkctl reload
networkctl status eth1
</syntaxhighlight>

Handing out addresses on the LAN is a separate job — see
[[DHCP and NTP for the LAN with systemd-networkd]].