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NAME

     ng_ipfw -- interface between netgraph and IP firewall

SYNOPSIS

     #include <netgraph/ng_ipfw.h>

DESCRIPTION

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

HOOKS

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

OPERATION

     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 ng_ipfw_tag.  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).

         struct ng_ipfw_tag {
                 struct m_tag    mt;             /* tag header */
                 struct ip_fw    *rule;          /* matching rule */
                 uint32_t        rule_id;        /* matching rule id */
                 uint32_t        chain_id;       /* ruleset id */
                 struct ifnet    *ifp;           /* interface, for ip_output */
                 int             dir;            /* packet direction */
         #define NG_IPFW_OUT     0
         #define NG_IPFW_IN      1
         };

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

CONTROL MESSAGES

     This node type supports only the generic control messages.

SHUTDOWN

     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.

SEE ALSO

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

HISTORY

     The ipfw node type was implemented in FreeBSD 6.0.

AUTHORS

     The ipfw node was written by Gleb Smirnoff <glebius@FreeBSD.org>.