NAME

ng_tee —

netgraph ``tee'' node type

SYNOPSIS

#include <sys/types.h>
#include <netgraph/ng_tee.h>

DESCRIPTION

The tee node type has a purpose similar to the tee(1) command. Tee nodes are useful for debugging or “snooping” on a connection between two netgraph nodes. Tee nodes have four hooks, right, left, right2left, and left2right. All data received on right is sent unmodified to both hooks left and right2left. Similarly, all data received on left is sent unmodified to both right and left2right.

Packets may also be received on right2left and left2right; if so, they are forwarded unchanged out hooks right and left, respectively.

HOOKS

This node type supports the following hooks:

right: The connection to the node on the right.
left: The connection to the node on the left.
right2left: Tap for right to left traffic.
left2right: Tap for left to right traffic.

CONTROL MESSAGES

This node type supports the generic control messages, plus the following.

NGM_TEE_GET_STATS (getstats): Get statistics, returned as a struct ng_tee_stats.
NGM_TEE_CLR_STATS (clrstats): Clear statistics.

SHUTDOWN

This node shuts down upon receipt of an NGM_SHUTDOWN control message, or when all hooks have been disconnected. If both right and left hooks are present, node removes itself from the chain gently, connecting right and left together.

HISTORY

The ng_tee node type was implemented in FreeBSD 4.0.

AUTHORS

Julian Elischer <julian@FreeBSD.org>