In case of a monolithic kernel all the device drivers are part of it. The hardware is accessed (and also configured) through its device driver. In case of Linux, the kernel presents for each device driver a representation in form of a device file. All device files are found in the codice_1 directory, and traditionally the device files for Ethernet hardware have been named codice_2, codice_3, etc. Since systemd, they are named differently: codice_4, etc. (This abstraction is called the everything is a file concept.)