.\" Copyright (c) 1996-1999 Whistle Communications, Inc.
.\" All rights reserved.
.\"
.\" Subject to the following obligations and disclaimer of warranty, use and
.\" redistribution of this software, in source or object code forms, with or
.\" without modifications are expressly permitted by Whistle Communications;
.\" provided, however, that:
.\" 1. Any and all reproductions of the source or object code must include the
.\"    copyright notice above and the following disclaimer of warranties; and
.\" 2. No rights are granted, in any manner or form, to use Whistle
.\"    Communications, Inc. trademarks, including the mark "WHISTLE
.\"    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
.\"    such appears in the above copyright notice or in the software.
.\"
.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
.\" OF SUCH DAMAGE.
.\"
.\" Author: Archie Cobbs <archie@FreeBSD.org>
.\"
.\" $FreeBSD: releng/12.2/share/man/man4/ng_UI.4 267938 2014-06-26 21:46:14Z bapt $
.\" $Whistle: ng_UI.8,v 1.4 1999/01/25 02:37:56 archie Exp $
.\"
.Dd January 19, 1999
.Dt NG_UI 4
.Os
.Sh NAME
.Nm ng_UI
.Nd UI netgraph node type
.Sh SYNOPSIS
.In netgraph/ng_UI.h
.Sh DESCRIPTION
The
.Nm UI
node type has two hooks,
.Dv upstream
and
.Dv downstream .
Packets received on
.Dv 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
.Dv upstream .
.Pp
Conversely, packets received on
.Dv upstream
will have a 0x03 byte prepended to them before being forwarded out on the
.Dv downstream
hook.
.Sh HOOKS
This node type supports the following hooks:
.Bl -tag -width ".Va downstream"
.It Va downstream
Downstream connection.
Packets on this side of the node have a 0x03 as
their first byte.
.It Va upstream
Upstream connection.
Packets on this side of the node have the
initial 0x03 byte stripped off.
.El
.Sh CONTROL MESSAGES
This node type supports only the generic control messages.
.Sh SHUTDOWN
This node shuts down upon receipt of a
.Dv NGM_SHUTDOWN
control message, or when both hooks have been disconnected.
.Sh SEE ALSO
.Xr netgraph 4 ,
.Xr ngctl 8
.Sh HISTORY
The
.Nm
node type was implemented in
.Fx 4.0 .
.Sh AUTHORS
.An Julian Elischer Aq Mt julian@FreeBSD.org