Network devices are low-level drivers that make it easier for applications and interfaces to work closely with network hardware.
ChorusOS systems provide two important types of network devices, Berkeley Packet Filters (BPF) and Teletype (tty, ptyp, ttyp) devices. Each network device described below requires both a device structure and a special file in order to function.
Refers to either a block or a raw device. All special files used for networking are raw (character) devices.
Has a major number. Major numbers are used by the system to select the corresponding device driver when several devices are configured.
Has a minor number. Minor numbers are not used directly by the system, but by the selected device driver.
By convention, special files are located in the /dev directory. Special files are created, usually during system initialization, using the mknod(1M) command.
A Berkeley Packet Filter is a special character device that allows applications to access all network packets directly, independently of network protocols. It is used in ChorusOS systems by networking utilities such as dhclient(1M) and rarp(1M).
The BPF device name is built from bpf concatenated with a unit number, N.
The BPF special file name takes the form /dev/bpfN.
Teletype character devices date from the time when systems actually wrote output on teletypewriters. ChorusOS systems use tty character devices for serial line communications. The two pseudo-tty devices, ptyp (master) and ttyp(slave), are used by PPP interfaces to detect when IP traffic occurs in order to configure tty devices for dial-up on demand.
The tty device name is built from tty concatenated with a unit number, N.
The tty special file names takes the form /dev/tty0M, /dev/ptyp0M, or /dev/ttyp0M, where M is 1, 2, 3....