---
name: "ng_hole"
section: "4"
platform: "linux"
package: "freebsd-manpages"
version: "6.0-5"
release: "Debian 4.0 (Etch)"
platforms: ["linux", "freebsd"]
url: "https://new.carta.tech/ng_hole"
---

# ng\_hole(4)

netgraph discard node type

## NAME

**ng\_hole** – netgraph discard node type

## SYNOPSIS

**#include \<sys/types.h\>**

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

## DESCRIPTION

The **hole** node type silently discards all data and control messages it receives. This type is used for testing and debugging.

## HOOKS

A **ng\_hole** node accepts any request to connect, regardless of the hook name, as long as the name is unique.

## CONTROL MESSAGES

This node type supports the generic control messages, plus the following:

- NGM\_BPF\_GET\_STATS

  This command takes an ASCII string argument, the hook name, and returns the statistics associated with the hook as a *struct ng\_hole\_hookstat*.

- NGM\_BPF\_CLR\_STATS

  This command takes an ASCII string argument, the hook name, and clears the statistics associated with the hook.

- NGM\_BPF\_GETCLR\_STATS

  This command is identical to NGM\_BPF\_GET\_STATS, except that the statistics are also atomically cleared.

## SHUTDOWN

This node shuts down upon receipt of a NGM\_SHUTDOWN control message, or when all hooks have been disconnected.

## SEE ALSO

[netgraph(4)](/netgraph/4.md), [ng\_echo(4)](/ng_echo/4.md), [ngctl(8)](/ngctl/8.md)

## HISTORY

The **ng\_hole** node type was implemented in FreeBSD 4.0.

## AUTHORS

Julian Elischer ⟨julian@FreeBSD.org⟩