Langue: en

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Version: 361731 (ubuntu - 24/10/10)

Section: 4 (Pilotes et protocoles réseau)

BSD mandoc


ng_ipfw - interface between netgraph and IP firewall


In 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 characters.


Once the 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 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 Vt 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 Vt struct ng_ipfw_tag 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 module.


ipfw(4), netgraph(4), ipfw(8), mbuf_tags9


The ipfw node type was implemented in Fx 6.0 .


The ipfw node was written by An Gleb Smirnoff Aq .