1.\" Copyright (c) 1996-1999 Whistle Communications, Inc. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, use and 5.\" redistribution of this software, in source or object code forms, with or 6.\" without modifications are expressly permitted by Whistle Communications; 7.\" provided, however, that: 8.\" 1. Any and all reproductions of the source or object code must include the 9.\" copyright notice above and the following disclaimer of warranties; and 10.\" 2. No rights are granted, in any manner or form, to use Whistle 11.\" Communications, Inc. trademarks, including the mark "WHISTLE 12.\" COMMUNICATIONS" on advertising, endorsements, or otherwise except as 13.\" such appears in the above copyright notice or in the software. 14.\" 15.\" THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 16.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 17.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 18.\" INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 19.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 20.\" WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 21.\" REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 22.\" SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 23.\" IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 24.\" RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 25.\" WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 26.\" PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 27.\" SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 28.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30.\" THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 31.\" OF SUCH DAMAGE. 32.\" 33.\" Author: Archie Cobbs <archie@FreeBSD.org> 34.\" 35.\" $FreeBSD$ 36.\" $Whistle: ng_pptpgre.8,v 1.2 1999/12/08 00:20:53 archie Exp $ 37.\" 38.Dd December 7, 2001 39.Dt NG_PPTPGRE 4 40.Os 41.Sh NAME 42.Nm ng_pptpgre 43.Nd PPTP GRE protocol netgraph node type 44.Sh SYNOPSIS 45.In sys/types.h 46.In netgraph/ng_pptpgre.h 47.Sh DESCRIPTION 48The 49.Nm pptpgre 50node type performs Generic Routing Encapsulation (GRE) over IP 51for the PPTP protocol as specified by RFC 2637. 52This involves packet 53encapsulation, sequencing, acknowledgement, and an adaptive timeout 54sliding window mechanism. 55This node type does not handle any of 56the TCP control protocol or call negotiation defined by PPTP. 57.Pp 58This node type expects to receive complete IP packets, 59including the IP header, on the 60.Dq Li lower 61hook, but it transmits outgoing frames without any IP header. 62The typical use for this node type would be to connect the 63.Dq Li upper 64hook to one of the link hooks of a 65.Xr ng_ppp 4 66node, and the 67.Dq Li lower 68hook to the 69.Dq Li "inet/raw/gre" 70hook of a 71.Xr ng_ksocket 4 72node. 73.Sh HOOKS 74This node type supports the following hooks: 75.Pp 76.Bl -tag -compact -width ".Li upper" 77.It Li upper 78Connection to the upper protocol layers 79.It Li lower 80Connection to the lower protocol layers 81.El 82.Sh CONTROL MESSAGES 83This node type supports the generic control messages, plus the following: 84.Bl -tag -width indent 85.It Dv NGM_PPTPGRE_SET_CONFIG 86This command resets and configures the node for a session. 87This command takes a 88.Vt "struct ng_pptpgre_conf" 89as an argument: 90.Bd -literal 91/* Configuration for a session */ 92struct ng_pptpgre_conf { 93 u_char enabled; /* enables traffic flow */ 94 u_char enableDelayedAck; /* enables delayed acks */ 95 u_char enableAlwaysAck; /* always send ack with data */ 96 u_char enableWindowing; /* enable windowing algorithm */ 97 u_int16_t cid; /* my call id */ 98 u_int16_t peerCid; /* peer call id */ 99 u_int16_t recvWin; /* peer recv window size */ 100 u_int16_t peerPpd; /* peer packet processing delay 101 (in 1/10 of a second) */ 102}; 103.Ed 104.Pp 105The 106.Va enabled 107field enables traffic flow through the node. 108The 109.Va enableDelayedAck 110field enables delayed acknowledgement (maximum 250 milliseconds), which 111is a useful optimization and should generally be turned on. 112.Va enableAlwaysAck 113field enables sending acknowledgements with every data packet, which 114is probably helpful as well. 115.Pp 116.Va enableWindowing 117enables the PPTP packet windowing mechanism specified by the protocol. 118Disabling this will cause the node to violate the protocol, possibly 119confusing other PPTP peers, but often results in better performance. 120The windowing mechanism is a design error in the PPTP protocol; 121L2TP, the successor to PPTP, removes it. 122.Pp 123The remaining fields are as supplied by the PPTP virtual call setup process. 124.It Dv NGM_PPTPGRE_GET_CONFIG 125Returns the current configuration as a 126.Vt "struct ng_pptpgre_conf" . 127.It Dv NGM_PPTPGRE_GET_STATS 128This command returns a 129.Vt "struct ng_pptpgre_stats" 130containing various node statistics. 131.It Dv NGM_PPTPGRE_CLR_STATS 132This command resets the node statistics. 133.It Dv NGM_PPTPGRE_GETCLR_STATS 134This command atomically gets and resets the node statistics, returning a 135.Vt "struct ng_pptpgre_stats" . 136.El 137.Sh SHUTDOWN 138This node shuts down upon receipt of a 139.Dv NGM_SHUTDOWN 140control message, or when both hooks have been disconnected. 141.Sh SEE ALSO 142.Xr netgraph 4 , 143.Xr ng_ksocket 4 , 144.Xr ng_ppp 4 , 145.Xr ngctl 8 146.Rs 147.%A K. Hamzeh 148.%A G. Pall 149.%A W. Verthein 150.%A J. Taarud 151.%A W. Little 152.%A G. Zorn 153.%T "Point-to-Point Tunneling Protocol (PPTP)" 154.%O RFC 2637 155.Re 156.Rs 157.%A S. Hanks 158.%A T. \&Li 159.%A D. Farinacci 160.%A P. Traina 161.%T "Generic Routing Encapsulation over IPv4 networks" 162.%O RFC 1702 163.Re 164.Sh HISTORY 165The 166.Nm 167node type was implemented in 168.Fx 4.0 . 169.Sh AUTHORS 170.An Archie Cobbs Aq archie@FreeBSD.org 171.Sh BUGS 172The node should not expect incoming GRE packets to have an IP header. 173This behavior is inherited from the (converse) behavior of raw IP sockets. 174An intermediate node that strips IP headers in one direction 175should be used instead. 176