NG_IPFW(4) BSD Kernel Interfaces Manual NG_IPFW(4)NAMEng_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) sub‐
systems.
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 dis‐
carded. 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 ALSOipfw(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⟩.
BSD June 10, 2009 BSD
