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: = "192.168.1.1"; = [ "8.8.8.8" ]; Statically configured interfaces are set up by the systemd service interface-name-cfg.service. The default gateway and name server configuration is performed by network-setup.service. The host name is set using : = "cartman"; The default host name is nixos. Set it to the empty string ("") to allow the DHCP server to provide the host name.