.\" Copyright (c) 2002 Mark Santcroos <marks@ripe.net>
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.\" $FreeBSD$
.\"
.Dd October 19, 2004
.Dt NG_DEVICE 4
.Os
.Sh NAME
.Nm ng_device
.Nd device netgraph node type
.Sh SYNOPSIS
.In netgraph/ng_device.h
.Sh DESCRIPTION
A
.Nm device
node is both a netgraph node and a system device interface.
When a
.Nm device
node is created, a new device entry appears which is accessible via the
regular file operators such as
.Xr open 2 ,
.Xr close 2 ,
.Xr read 2 ,
.Xr write 2 ,
etc.
.Pp
The first node is created as
.Pa /dev/ngd0 ,
all subsequent nodes
.Pa /dev/ngd1 , /dev/ngd2 ,
etc.
.Sh HOOKS
A
.Nm device
node has a single hook with an arbitrary name.
All data coming in over the hook will be presented to the device
for
.Xr read 2 .
All data coming in from the device entry by
.Xr write 2
will be forwarded to the hook.
.Sh CONTROL MESSAGES
The
.Nm device
node supports one non-generic control message:
.Bl -tag -width 3n
.It Dv NGM_DEVICE_GET_DEVNAME
Returns device name corresponding to a node.
.El
.\" Additionally, the node accepts
.\" .Xr ioctl 2 Ns s
.\" from the device entry.
.\" These will be encapsulated into
.\" .Xr netgraph 4
.\" messages and send out to the hook.
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, or upon hook disconnection.
The associated device entry is removed and becomes available
for use by future
.Nm device
nodes.
.Sh SEE ALSO
.Xr netgraph 4 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm device
node type was first implemented in
.Fx 5.0 .
.Sh AUTHORS
.An Mark Santcroos Aq Mt marks@ripe.net
.An Gleb Smirnoff Aq Mt glebius@FreeBSD.org