In many Unix operating systems, the network devices have appearances in the /dev directory. This is not so in Linux. In Linux, the network devices are created dynamically in software, and they do not require device files to be present.
In the majority of cases, the network device is automatically created by the device driver (while it is initializing and locating your hardware). For example, the Ethernet device driver creates eth[0..n] interfaces sequentially as it locates your Ethernet hardware. The first Ethernet card found becomes eth0, the second eth1 etc.
In some cases though, notably with slip and ppp, the network devices are created through the action of some user program. The same sequential device numbering applies, but the devices are not created automatically at boot time. The reason for this is that unlike Ethernet devices, the number of active slip or ppp devices may vary during the uptime of the machine. These cases will be covered in more detail in later sections. Was this section helpful? Why not Donate $2.50?