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.\" $FreeBSD$
.\" $Whistle: nghook.8,v 1.4 1999/01/20 03:19:45 archie Exp $
.\"
.Dd October 24, 2003
.Dt NGHOOK 8
.Os
.Sh NAME
.Nm nghook
.Nd connect to a
.Xr netgraph 4
node
.Sh SYNOPSIS
.Nm
.Op Fl adlnSs
.Op Fl m Ar msg
.Ar path
.Op Ar hookname
.Nm
.Fl e
.Op Fl n
.Op Fl m Ar msg
.Ar path
.Ar hookname
.Ar program
.Op Ar args ...
.Sh DESCRIPTION
The
.Nm
utility creates a
.Xr ng_socket 4
socket type node and connects it to hook
.Ar hookname
of the node found at
.Ar path .
If
.Ar hookname
is omitted,
.Dq Li debug
is assumed.
.Pp
If the
.Fl e
option is given, the third argument is interpreted as the path to a program,
and this program is executed with the remaining arguments as its arguments.
Before executing, the program Netgraph messages (specified by the
.Fl m
option) are sent to the node.
The program is executed with its standard input (unless closed by
.Fl n )
and output connected to the hook.
.Pp
If the
.Fl e
option is not given, all data written to standard input is sent
to the node, and all data received from the node is relayed
to standard output.
Messages specified with
.Fl m
are sent to the node before the loop is entered.
The
.Nm
utility exits when
.Dv EOF
is detected on standard input in this case.
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl a
Output each packet read in human-readable decoded
.Tn ASCII
form instead of raw binary.
.It Fl d
Increase the debugging verbosity level.
.It Fl e
Execute the program specified by the third argument.
.It Fl l
Loops all received data back to the hook in addition to writing it
to standard output.
.It Fl m Ar msg
Before executing the program (in
.Fl e
mode) send the given ASCII control message to the node.
This option may be given more than once.
.It Fl n
Do not attempt to read any data from standard input.
The
.Nm
utility will continue reading from the node until stopped by a signal.
.It Fl S
Use file descriptor 0 for output instead of the default 1.
.It Fl s
Use file descriptor 1 for input instead of the default 0.
.El
.Sh SEE ALSO
.Xr netgraph 3 ,
.Xr netgraph 4 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm netgraph
system was designed and first implemented at Whistle Communications, Inc.\&
in a version of
.Fx 2.2
customized for the Whistle InterJet.
.Sh AUTHORS
.An Archie Cobbs Aq archie@whistle.com
.Sh BUGS
Although all input is read in unbuffered mode,
there is no way to control the packetization of the input.
.Pp
If the node sends a response to a message (specified by
.Fl m ) ,
this response is lost.