---
name: "ng_UI"
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_UI"
---

# ng\_UI(4)

UI netgraph node type

## NAME

**ng\_UI** – UI netgraph node type

## SYNOPSIS

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

## DESCRIPTION

The **UI** node type has two hooks, upstream and downstream. Packets received on downstream must have 0x03 (indicating unnumbered information) as their first byte; if not the packet is dropped. This byte is then stripped and the remainder of the packet sent out on upstream.

Conversely, packets received on upstream will have a 0x03 byte prepended to them before being forwarded out on the downstream hook.

## HOOKS

This node type supports the following hooks:

- downstream

  Downstream connection. Packets on this side of the node have a 0x03 as their first byte.

- upstream

  Upstream connection. Packets on this side of the node have the initial 0x03 byte stripped off.

## CONTROL MESSAGES

This node type supports only the generic control messages.

## SHUTDOWN

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

## SEE ALSO

[netgraph(4)](/netgraph/4.md), [ngctl(8)](/ngctl/8.md)

## HISTORY

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

## AUTHORS

Julian Elischer ⟨julian@FreeBSD.org⟩