nghook(8)

NAME

nghook - connect to a netgraph(4) node

SYNOPSIS

nghook [-adlnSs] [-m msg] path [hookname]
nghook -e [-n] [-m msg] path hookname program [args ...]

DESCRIPTION

The nghook utility creates a ng_socket(4) socket type node

and connects
it to hook hookname of the node found at path. If hookname

is omitted,
``debug'' is assumed.

If the -e option is given, the third argument is interpreted

as the path
to a program, and this program is executed with the remain

ing arguments
as its arguments. Before executing, the program Netgraph

messages (specified by the -m option) are sent to the node. The program

is executed
with its standard input (unless closed by -n) and output

connected to the
hook.

If the -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 -m are sent to the node be

fore the loop
is entered. The nghook utility exits when EOF is detected

on standard
input in this case.

The options are as follows:

-a Output each packet read in human-readable decoded

ASCII form

instead of raw binary.

-d Increase the debugging verbosity level.

-e Execute the program specified by the third argument.

-l Loops all received data back to the hook in addition

to writing

it to standard output.

-m msg Before executing the program (in -e mode) send the

given ASCII

control message to the node. This option may be

given more than
once.

-n Do not attempt to read any data from standard input.

The nghook

utility will continue reading from the node until

stopped by a
signal.

-S Use file descriptor 0 for output instead of the de

fault 1.

-s Use file descriptor 1 for input instead of the de

fault 0.

SEE ALSO

netgraph(3), netgraph(4), ngctl(8)

HISTORY

The netgraph system was designed and first implemented at

Whistle Communications, Inc. in a version of FreeBSD 2.2 customized for

the Whistle
InterJet.

AUTHORS

Archie Cobbs <archie@whistle.com>

BUGS

Although all input is read in unbuffered mode, there is no

way to control
the packetization of the input.

If the node sends a response to a message (specified by -m),

this
response is lost.

BSD October 24, 2003

BSD