Pseudo-Devices

These are things that act like hardware, but have no actual hardware attached. Most are found on all architectures. If a number appears after a pseudo-device driver, that is the total number of the particular pseudo-device driver the system will support.

Disk-Like Pseudo-Devices

pseudo-device

vnd

4

This is a disk-like interface to files, for a variety of filesystem tricks. See Chapter 15.

pseudo-device

ccd

4

This allows you to combine multiple disks into one large concatenated disk. See ccd(4).

pseudo-device

raid

4

This is the RAIDframe software RAID system. See raid(4).

Networking Pseudo-Devices

These pseudo-devices provide different methods of accessing the network.

pseudo-device

pf

1

This is OpenBSD's integrated packet filter, and is discussed in Chapters 17 through 19.

pseudo-device

pflog

1

This device lets pf log what it does, and is also discussed in Chapters 17 through 19.

pseudo-device

loop

2

This is the loopback device. If you remove it, many programs will break in an entertaining way. See lo(4) for details.

pseudo-device

bpfilter

8

This supports the Berkeley Packet Filter, the standard packet sniffer.

pseudo-device

sl

2

This supports SLIP, the popular pre-PPP dialup protocol.

pseudo-device

ppp

2

This lets you connect to the Internet with dialup connections using pppd(8). I recommend using user-mode ppp, which requires tun devices instead of this. See Chapter 9.

pseudo-device

sppp

1

This supports Synchronous PPP. Most people have no need of it, but see sppp(4) if you're curious.

pseudo-device

tun

2

This is a tunneling network device, used by user-mode ppp and a variety of VPN tools. We discuss using tun with ppp in Chapter 9.

pseudo-device

bridge

2

man: brconfig(8)

Bridging is where two separate Ethernet segments are connected transparently.

pseudo-device

vlan

2

This lets you divide a single Ethernet into two segments, or virtual lans. See vlan(4).

pseudo-device

gre

1

This supports Cisco Generic Routing Encapsulation, a common VPN protocol. See gre(4).

pseudo-device

pty

64

Pseudo-terminals are software terminals. Every remote shell connection needs a pseudo-terminal. See pty(4).

pseudo-device

tb

1

This supports many popular serial digitizers. See tb(4).

pseudo-device

ksyms

1

This lets a programmer pull symbol names from a running kernel. It's very useful for kernel developers; see ksyms(4).

IPv6 Pseudo-Devices

While we're not covering IPv6 in this book, the following IPv6 devices are included in the GENERIC kernel and so should be mentioned.

pseudo-device

gif

4

This is a generic IP tunnel, allowing you to tunnel either IPv4 or IPv6 over IPv4 or IPv6. See gif(4).

pseudo-device

faith

1

This pseudo-device can capture IPv6 traffic and relay it to a userland program. See faith(4).

pseudo-device

enc

1

The encapsulation interface allows the system to send IPv6 traffic through pf(4). See enc(4).

Miscellaneous Pseudo-Devices

The following pseudo-devices really don't fit anywhere else.

pseudo-device

pctr

1

This adds hooks for performance counters, discussed in pctr(1).

pseudo-device

mtrr

1

This pseudo-device provides access to the memory range attributes supported on Pentium CPUs. See mtrr(4).

pseudo-device

sequencer

1

This supports MIDI sequencers.

pseudo-device

wsmux

2

This is a virtual multiplexor for the wscons virtual console framework.

pseudo-device

crypto

1

This provides userland programs a generic interface to hardware cryptographic support through the kernel. See crypto(4).