|| FreeBSD Kernel Interfaces Manual
netgraph echo node type
echo node type reflects all data and control messages back to the sender. This node type is used for testing and debugging.
echo node accepts any request to connect, regardless of the hook name, as long as the name is unique.
CONTROL MESSAGES This node type supports only the generic control messages. Any other control messages are reflected back to the sender.
SHUTDOWN This node shuts down upon receipt of a
NGM_SHUTDOWN control message, or when all hooks have been disconnected.
ng_echo node type was implemented in