NG_IPFW(4) MidnightBSD Kernel Interfaces Manual NG_IPFW(4)

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 */

struct ifnet

*ifp;

/* interface, for ip_output */

int

dir;

/* packet direction */

#define

NG_IPFW_OUT

0

#define

NG_IPFW_IN

1

int

flags;

/* flags, for ip_output() */

};

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〉.

MidnightBSD 0.3 February 5, 2005 MidnightBSD 0.3