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NG_PPTPGRE(4) FreeBSD Kernel Interfaces Manual NG_PPTPGRE(4) NAME ng_pptpgre -- PPTP GRE protocol netgraph node type SYNOPSIS #include <sys/types.h> #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, acknowledgement, and an adaptive timeout slid- ing window mechanism. This node type does not handle any of the TCP con- trol 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: session_hhhh Session 0xhhhh data packets to the upper protocol layers upper Same as session_hhhh, but for single session with config- urable cid (legacy) 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 hook for a session. If corre- sponding session_hhhh hook is not connected, upper hook will be configured. 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_char enableWindowing; /* enable windowing algorithm */ 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 gen- erally be turned on. enableAlwaysAck field enables sending acknowledgements with every data packet, which is probably help- ful as well. enableWindowing enables the PPTP packet windowing mechanism spec- ified by the protocol. Disabling this will cause the node to violate the protocol, possibly confusing other PPTP peers, but often results in better performance. The windowing mechanism is a design error in the PPTP protocol; L2TP, the successor to PPTP, removes it. The remaining fields are as supplied by the PPTP virtual call setup process. NGM_PPTPGRE_GET_CONFIG Takes two byte argument as cid and returns the current configura- tion as a struct ng_pptpgre_conf. NGM_PPTPGRE_GET_STATS This command returns a struct ng_pptpgre_stats containing various node statistics. NGM_PPTPGRE_CLR_STATS This command resets the node statistics. NGM_PPTPGRE_GETCLR_STATS This command atomically gets and resets the node statistics, returning a struct ng_pptpgre_stats. 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(4), ng_ppp(4), ngctl(8) K. Hamzeh, G. Pall, W. Verthein, J. Taarud, W. Little, and G. Zorn, Point-to-Point Tunneling Protocol (PPTP), RFC 2637. S. Hanks, T. Li, D. Farinacci, and 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@FreeBSD.org> BUGS The node should not expect incoming GRE packets to have an IP header. This behavior is inherited from the (converse) behavior of raw IP sock- ets. An intermediate node that strips IP headers in one direction should be used instead. FreeBSD 11.1 March 29, 2008 FreeBSD 11.1
NAME | SYNOPSIS | DESCRIPTION | HOOKS | CONTROL MESSAGES | SHUTDOWN | SEE ALSO | HISTORY | AUTHORS | BUGS
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