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.\" Author: Archie Cobbs <archie@FreeBSD.org>
.\"
.\" $FreeBSD: src/share/man/man4/ng_hole.4,v 1.13.2.1.6.1 2010/12/21 17:09:25 kensmith Exp $
.\" $Whistle: ng_hole.8,v 1.4 1999/01/25 23:46:26 archie Exp $
.\"
.Dd May 19, 2004
.Dt NG_HOLE 4
.Os
.Sh NAME
.Nm ng_hole
.Nd netgraph discard node type
.Sh SYNOPSIS
.In sys/types.h
.In netgraph/ng_hole.h
.Sh DESCRIPTION
The
.Nm hole
node type silently discards all data and control messages it receives.
This type is used for testing and debugging.
.Sh HOOKS
A
.Nm
node accepts any request to connect, regardless of the hook name,
as long as the name is unique.
.Sh CONTROL MESSAGES
This node type supports the generic control messages, plus the
following:
.Bl -tag -width indent
.It Dv NGM_HOLE_GET_STATS
This command takes an
.Tn ASCII
string argument, the hook name, and returns the statistics
associated with the hook as a
.Vt "struct ng_hole_hookstat" .
.It Dv NGM_HOLE_CLR_STATS
This command takes an
.Tn ASCII
string argument, the hook name, and clears the statistics
associated with the hook.
.It Dv NGM_HOLE_GETCLR_STATS
This command is identical to
.Dv NGM_HOLE_GET_STATS ,
except that the statistics are also atomically cleared.
.El
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, or when all hooks have been disconnected.
.Sh SEE ALSO
.Xr netgraph 4 ,
.Xr ng_echo 4 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 4.0 .
.Sh AUTHORS
.An Julian Elischer Aq julian@FreeBSD.org