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.
SEE ALSO¶
tee(1),
netgraph(4),
ngctl(8)
HISTORY¶
The
ng_tee node type was implemented in
FreeBSD 4.0.
AUTHORS¶
Julian Elischer
⟨julian@FreeBSD.org⟩
