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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>