ng_pptpgre(4) - Manual pages

NAME

ng_pptpgre — PPTP GRE protocol netgraph node type

SYNOPSIS

#include <netgraph/pptpgre/ng_pptpgre.h>

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, acknowledgement, 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.

This node type expects to receive complete IP packets, including the IP header, on the “lower” hook, but it transmits outgoing frames without any IP header. The typical use for this node type would be to connect the “upper” hook to one of the link hooks of a ng_ppp(4) node, and the “lower” hook to the “inet/raw/gre” hook of a ng_ksocket(4) 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_char      enableAlwaysAck;  /* always send ack with data */
    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 milliseconds), which is a useful optimization and should generally be turned on. enableAlwaysAck field enables sending acknowledgements with every data packet, which is probably helpful as well. The remaining fields are as supplied by the PPTP virtual call setup process.

NGM_PPTPGRE_GET_CONFIG