NG_TEE(4) |
FreeBSD Kernel Interfaces Manual |
NG_TEE(4) |
NAME
ng_tee —
netgraph ``tee'' node type
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>