IPv4 Configuration {#sec-ipv4}

By default, NixOS uses DHCP (specifically, dhcpcd) to automatically configure network interfaces. However, you can configure an interface manually as follows:

{
  networking.interfaces.eth0.ipv4.addresses = [
    {
      address = "192.168.1.2";
      prefixLength = 24;
    }
  ];
}

Typically you'll also want to set a default gateway and set of name servers:

{
  networking.defaultGateway = "192.168.1.1";
  networking.nameservers = [ "8.8.8.8" ];
}

::: {.note} Addresses and routes for statically configured interfaces and the default gateway are set up by systemd services named network-addresses-<interface>.service. The name servers configuration, instead, is performed by network-local-commands.service using resolvconf. :::

::: {.note} If needed, for example if addresses/routes were added/removed, you can reset the network configuration by running systemctl restart networking-scripted.target :::

The host name is set using :

{ networking.hostName = "cartman"; }

The default host name is nixos. Set it to the empty string ("") to allow the DHCP server to provide the host name.