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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 November 4, 2018 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.Bl -tag -width ".Va session_hhhh" 76.It Va session_hhhh 77Session 0xhhhh data packets to the upper protocol layers 78.It Va upper 79Same as session_hhhh, but for single session with configurable cid (legacy) 80.It Va lower 81Connection to the lower protocol layers 82.El 83.Sh CONTROL MESSAGES 84This node type supports the generic control messages, plus the following: 85.Bl -tag -width foo 86.It Dv NGM_PPTPGRE_SET_CONFIG Pq Ic setconfig 87This command resets and configures hook for a session. 88If corresponding 89session_hhhh hook is not connected, upper hook will be configured. 90This command takes a 91.Vt "struct ng_pptpgre_conf" 92as an argument: 93.Bd -literal 94/* Configuration for a session */ 95struct ng_pptpgre_conf { 96 u_char enabled; /* enables traffic flow */ 97 u_char enableDelayedAck; /* enables delayed acks */ 98 u_char enableAlwaysAck; /* always include ack with data */ 99 u_char enableWindowing; /* enable windowing algorithm */ 100 uint16_t cid; /* my call id */ 101 uint16_t peerCid; /* peer call id */ 102 uint16_t recvWin; /* peer recv window size */ 103 uint16_t peerPpd; /* peer packet processing delay 104 (in 1/10 of a second) */ 105}; 106.Ed 107.Pp 108The 109.Va enabled 110field enables traffic flow through the node. 111The 112.Va enableDelayedAck 113field enables delayed acknowledgement (maximum 250 milliseconds), which 114is a useful optimization and should generally be turned on. 115.Va enableAlwaysAck 116field enables sending acknowledgements with every data packet, which 117is probably helpful as well. 118.Pp 119.Va enableWindowing 120enables the PPTP packet windowing mechanism specified by the protocol. 121Disabling this will cause the node to violate the protocol, possibly 122confusing other PPTP peers, but often results in better performance. 123The windowing mechanism is a design error in the PPTP protocol; 124L2TP, the successor to PPTP, removes it. 125.Pp 126The remaining fields are as supplied by the PPTP virtual call setup process. 127.It Dv NGM_PPTPGRE_GET_CONFIG Pq Ic getconfig 128Takes two byte argument as cid and returns the current configuration as a 129.Vt "struct ng_pptpgre_conf" . 130.It Dv NGM_PPTPGRE_GET_STATS Pq Ic getstats 131This command returns a 132.Vt "struct ng_pptpgre_stats" 133containing various node statistics. 134.It Dv NGM_PPTPGRE_CLR_STATS Pq Ic clrstats 135This command resets the node statistics. 136.It Dv NGM_PPTPGRE_GETCLR_STATS Pq Ic getclrstats 137This command atomically gets and resets the node statistics, returning a 138.Vt "struct ng_pptpgre_stats" . 139.El 140.Sh SHUTDOWN 141This node shuts down upon receipt of a 142.Dv NGM_SHUTDOWN 143control message, or when both hooks have been disconnected. 144.Sh SYSCTL VARIABLES 145A set of 146.Xr sysctl 8 147variables controls ability of this node to deal with some 148amount of packet reorder that sometimes happens in transit. 149Packet reorder results in packet drops (unless the order is restored) 150as PPP protocol can not deliver reordered data. 151These variables are shown below together 152with their default value and meaning: 153.Bl -tag -width indent 154.It Va net.graph.pptpgre.reorder_max: 1 155Defines maximum length of node's private reorder queue 156used to keep data waiting for late packets. 157Zero value disables reordering. 158Default value allows the node to restore the order for two packets swapped 159in transit. 160Greater values allow the node to deliver packets being late after more 161packets in sequence at cost of increased kernel memory usage. 162.It Va net.graph.pptpgre.reorder_timeout: 1 163Defines time value in miliseconds used to wait for late packets. 164.El 165.Sh SEE ALSO 166.Xr netgraph 4 , 167.Xr ng_ksocket 4 , 168.Xr ng_ppp 4 , 169.Xr ngctl 8 , 170.Xr sysctl 8 171.Rs 172.%A K. Hamzeh 173.%A G. Pall 174.%A W. Verthein 175.%A J. Taarud 176.%A W. Little 177.%A G. Zorn 178.%T "Point-to-Point Tunneling Protocol (PPTP)" 179.%O RFC 2637 180.Re 181.Rs 182.%A S. Hanks 183.%A T. \&Li 184.%A D. Farinacci 185.%A P. Traina 186.%T "Generic Routing Encapsulation over IPv4 networks" 187.%O RFC 1702 188.Re 189.Sh HISTORY 190The 191.Nm 192node type was implemented in 193.Fx 4.0 . 194.Sh AUTHORS 195.An Archie Cobbs Aq Mt archie@FreeBSD.org 196.Sh BUGS 197The node should not expect incoming GRE packets to have an IP header. 198This behavior is inherited from the (converse) behavior of raw IP sockets. 199An intermediate node that strips IP headers in one direction 200should be used instead. 201