<section xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="sec-ipv4">

<title>IPv4 Configuration</title>

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

<programlisting>
networking.interfaces.eth0.ip4 = [ { address = "192.168.1.2"; prefixLength = 24; } ];
</programlisting>

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

<programlisting>
networking.defaultGateway = "192.168.1.1";
networking.nameservers = [ "8.8.8.8" ];
</programlisting>

</para>

<note><para>Statically configured interfaces are set up by the systemd
service
<replaceable>interface-name</replaceable><literal>-cfg.service</literal>.
The default gateway and name server configuration is performed by
<literal>network-setup.service</literal>.</para></note>

<para>The host name is set using <option>networking.hostName</option>:

<programlisting>
networking.hostName = "cartman";
</programlisting>

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

</section>