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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
          Get statistics, returned as a struct ng_tee_stats.

     NGM_TEE_CLR_STATS
          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