179 lines
6.3 KiB
Groff
179 lines
6.3 KiB
Groff
.\" Copyright (c) 1996-1999 Whistle Communications, Inc.
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.\" All rights reserved.
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.\"
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.\" Subject to the following obligations and disclaimer of warranty, use and
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.\" redistribution of this software, in source or object code forms, with or
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.\" without modifications are expressly permitted by Whistle Communications;
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.\" provided, however, that:
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.\" 1. Any and all reproductions of the source or object code must include the
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.\" copyright notice above and the following disclaimer of warranties; and
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.\" 2. No rights are granted, in any manner or form, to use Whistle
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.\" Communications, Inc. trademarks, including the mark "WHISTLE
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.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as
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.\" such appears in the above copyright notice or in the software.
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.\"
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.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
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.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
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.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
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.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
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.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
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.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
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.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
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.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
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.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
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.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
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.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
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.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
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.\" OF SUCH DAMAGE.
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.\"
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.\" Author: Archie Cobbs <archie@FreeBSD.org>
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.\"
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.\" $FreeBSD$
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.\" $Whistle: ng_pptpgre.8,v 1.2 1999/12/08 00:20:53 archie Exp $
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.\"
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.Dd March 29, 2008
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.Dt NG_PPTPGRE 4
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.Os
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.Sh NAME
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.Nm ng_pptpgre
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.Nd PPTP GRE protocol netgraph node type
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.Sh SYNOPSIS
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.In sys/types.h
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.In netgraph/ng_pptpgre.h
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.Sh DESCRIPTION
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The
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.Nm pptpgre
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node type performs Generic Routing Encapsulation (GRE) over IP
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for the PPTP protocol as specified by RFC 2637.
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This involves packet
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encapsulation, sequencing, acknowledgement, and an adaptive timeout
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sliding window mechanism.
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This node type does not handle any of
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the TCP control protocol or call negotiation defined by PPTP.
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.Pp
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This node type expects to receive complete IP packets,
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including the IP header, on the
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.Dq Li lower
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hook, but it transmits outgoing frames without any IP header.
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The typical use for this node type would be to connect the
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.Dq Li upper
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hook to one of the link hooks of a
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.Xr ng_ppp 4
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node, and the
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.Dq Li lower
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hook to the
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.Dq Li "inet/raw/gre"
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hook of a
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.Xr ng_ksocket 4
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node.
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.Sh HOOKS
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This node type supports the following hooks:
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.Pp
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.Bl -tag -compact -width ".Li session_hhhh"
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.It Li session_hhhh
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Session 0xhhhh data packets to the upper protocol layers
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.It Li upper
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Same as session_hhhh, but for single session with configurable cid (legacy)
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.It Li lower
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Connection to the lower protocol layers
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.El
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.Sh CONTROL MESSAGES
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This node type supports the generic control messages, plus the following:
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.Bl -tag -width indent
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.It Dv NGM_PPTPGRE_SET_CONFIG
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This command resets and configures hook for a session. If corresponding
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session_hhhh hook is not connected, upper hook will be configured.
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This command takes a
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.Vt "struct ng_pptpgre_conf"
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as an argument:
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.Bd -literal
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/* Configuration for a session */
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struct ng_pptpgre_conf {
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u_char enabled; /* enables traffic flow */
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u_char enableDelayedAck; /* enables delayed acks */
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u_char enableAlwaysAck; /* always send ack with data */
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u_char enableWindowing; /* enable windowing algorithm */
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u_int16_t cid; /* my call id */
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u_int16_t peerCid; /* peer call id */
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u_int16_t recvWin; /* peer recv window size */
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u_int16_t peerPpd; /* peer packet processing delay
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(in 1/10 of a second) */
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};
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.Ed
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.Pp
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The
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.Va enabled
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field enables traffic flow through the node.
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The
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.Va enableDelayedAck
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field enables delayed acknowledgement (maximum 250 milliseconds), which
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is a useful optimization and should generally be turned on.
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.Va enableAlwaysAck
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field enables sending acknowledgements with every data packet, which
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is probably helpful as well.
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.Pp
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.Va enableWindowing
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enables the PPTP packet windowing mechanism specified by the protocol.
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Disabling this will cause the node to violate the protocol, possibly
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confusing other PPTP peers, but often results in better performance.
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The windowing mechanism is a design error in the PPTP protocol;
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L2TP, the successor to PPTP, removes it.
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.Pp
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The remaining fields are as supplied by the PPTP virtual call setup process.
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.It Dv NGM_PPTPGRE_GET_CONFIG
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Takes two byte argument as cid and returns the current configuration as a
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.Vt "struct ng_pptpgre_conf" .
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.It Dv NGM_PPTPGRE_GET_STATS
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This command returns a
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.Vt "struct ng_pptpgre_stats"
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containing various node statistics.
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.It Dv NGM_PPTPGRE_CLR_STATS
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This command resets the node statistics.
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.It Dv NGM_PPTPGRE_GETCLR_STATS
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This command atomically gets and resets the node statistics, returning a
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.Vt "struct ng_pptpgre_stats" .
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.El
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.Sh SHUTDOWN
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This node shuts down upon receipt of a
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.Dv NGM_SHUTDOWN
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control message, or when both hooks have been disconnected.
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.Sh SEE ALSO
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.Xr netgraph 4 ,
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.Xr ng_ksocket 4 ,
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.Xr ng_ppp 4 ,
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.Xr ngctl 8
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.Rs
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.%A K. Hamzeh
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.%A G. Pall
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.%A W. Verthein
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.%A J. Taarud
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.%A W. Little
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.%A G. Zorn
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.%T "Point-to-Point Tunneling Protocol (PPTP)"
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.%O RFC 2637
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.Re
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.Rs
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.%A S. Hanks
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.%A T. \&Li
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.%A D. Farinacci
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.%A P. Traina
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.%T "Generic Routing Encapsulation over IPv4 networks"
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.%O RFC 1702
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.Re
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.Sh HISTORY
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The
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.Nm
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node type was implemented in
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.Fx 4.0 .
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.Sh AUTHORS
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.An Archie Cobbs Aq archie@FreeBSD.org
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.Sh BUGS
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The node should not expect incoming GRE packets to have an IP header.
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This behavior is inherited from the (converse) behavior of raw IP sockets.
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An intermediate node that strips IP headers in one direction
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should be used instead.
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