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     ng_ipfw — interface between netgraph and IP firewall


     #include <netinet/ip_var.h>
     #include <netgraph/ng_ipfw.h>


     The ipfw node implements interface between ipfw(4) and netgraph(4) subsystems.


     The ipfw node supports an arbitrary number of hooks, which must be named using only numeric


     Once the ng_ipfw module is loaded into the kernel, a single node named ipfw is automatically
     created.  No more ipfw nodes can be created.  Once destroyed, the only way to recreate the
     node is to reload the ng_ipfw module.

     Packets can be injected into netgraph(4) using either the netgraph or ngtee commands of the
     ipfw(8) utility.  These commands require a numeric cookie to be supplied as an argument.
     Packets are sent out of the hook whose name equals the cookie value.  If no hook matches,
     packets are discarded.  Packets injected via the netgraph command are tagged with struct
     ipfw_rule_ref.  This tag contains information that helps the packet to re-enter ipfw(4)
     processing, should the packet come back from netgraph(4) to ipfw(4).

     Packets received by a node from netgraph(4) subsystem must be tagged with struct
     ipfw_rule_ref tag.  Packets re-enter IP firewall processing at the next rule.  If no tag is
     supplied, packets are discarded.


     This node type supports only the generic control messages.


     This node shuts down upon receipt of a NGM_SHUTDOWN control message.  Do not do this, since
     the new ipfw node can only be created by reloading the ng_ipfw module.


     ipfw(4), netgraph(4), ipfw(8), mbuf_tags(9)


     The ipfw node type was implemented in FreeBSD 6.0.


     The ipfw node was written by Gleb Smirnoff <>.