---
name: "ng_ipfw"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/ng_ipfw"
---

# ng\_ipfw(4)

IP firewall netgraph node

## NAME

**ng\_ipfw** – IP firewall netgraph node

## SYNOPSIS

**#include \<netinet/ip\_var.h\>**

**#include \<netgraph/ng\_ipfw.h\>**

## DESCRIPTION

The **ipfw** node implements interface between [ipfw(4)](/ipfw/4.md) and [netgraph(4)](/netgraph/4.md) 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)](/netgraph/4.md) using either the **netgraph** or **ngtee** commands of the [ipfw(8)](/ipfw/8.md) 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 ipfw\_rule\_ref*. This tag contains information that helps the packet to re-enter [ipfw(4)](/ipfw/4.md) processing, should the packet come back from [netgraph(4)](/netgraph/4.md) to [ipfw(4)](/ipfw/4.md).

Packets received by a node from [netgraph(4)](/netgraph/4.md) subsystem must be tagged with *struct ipfw\_rule\_ref* 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)](/ipfw/4.md), [netgraph(4)](/netgraph/4.md), [ipfw(8)](/ipfw/8.md), [mbuf\_tags(9)](/mbuf_tags/9.md)

## HISTORY

The **ipfw** node type was implemented in FreeBSD 6.0.

## AUTHORS

The **ipfw** node was written by Gleb Smirnoff ⟨*glebius@FreeBSD.org*⟩.