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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>.