NG_PPTPGRE(8)

NAME
ng_pptpgre - PPTP GRE protocol netgraph node type

SYNOPSIS
#include <netgraph/ng_pptpgre.h>

DESCRIPTION
The pptpgre node type performs Generic Routing Encapsulation (GRE) over IP for the PPTP protocol as specified by RFC 2637. This involves packet encapsulation, sequencing, acknowlegement, and an adaptive timeout sliding window mechanism. This node type does not handle any of the TCP control protocol or call negotiation defined by PPTP.

The typical use for this node type would be to connect the upper hook to one of the link hooks of a ng_ppp(8) node, and the lower hook to the inet/raw/gre hook of a ng_ksocket(8) node.

HOOKS
This node type supports the following hooks:

upper
    Connection to the upper protocol layers
lower
    Connection to the lower protocol layers

CONTROL MESSAGES
This node type supports the generic control messages, plus the following:

NGM_PPTPGRE_SET_CONFIG
    This command resets and configures the node for a session. This command takes a struct ng_pptpgre_conf as an argument:

        /* Configuration for a session */
        struct ng_pptpgre_conf {
            u_char      enabled;          /* enables traffic flow */
            u_char      enableDelayedAck; /* enables delayed acks */
            u_int16_t   cid;              /* my call id */
            u_int16_t   peerCid;          /* peer call id */
            u_int16_t   recvWin;          /* peer recv window size */
            u_int16_t   peerPpd;          /* peer packet processing delay
                                             (in 1/10 of a second) */
        };

    The enabled field enables traffic flow through the node. The enableDelayedAck field enables delayed acknowledgement (maximum 250 miliseconds), which is a useful optimization and should generally be turned on. The remaining fields are as supplied by the PPTP virtual call setup process.

NGM_PPTPGRE_GET_CONFIG
    Returns the current configuration as a struct ng_pptpgre_conf.

SHUTDOWN
This node shuts down upon receipt of a NGM_SHUTDOWN control message, or when both hooks have been disconnected.

SEE ALSO
netgraph(4), ng_ksocket(8), ng_ppp(8), ngctl(8). K. Hamzeh, G. Pall, W. Verthein, J. Taarud, W. Little, G. Zorn, Point-to-Point Tunneling Protocol (PPTP), RFC 2637. S. Hanks, T. Li, D. Farinacci, P. Traina, Generic Routing Encapsulation over IPv4 networks, RFC 1702.

HISTORY
The ng_pptpgre node type was implemented in FreeBSD 4.0.

AUTHORS
Archie Cobbs <archie@whistle.com>