svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
ng_pptpgre(4)
NG_PPTPGRE(4) BSD 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 (setconfig)
This command resets and configures hook for a session. If corre‐
sponding session_hhhh hook is not connected, upper hook will be con‐
figured. This command takes a struct ng_pptpgre_conf as an argu‐
ment:
/* Configuration for a session */
struct ng_pptpgre_conf {
u_char enabled; /* enables traffic flow */
u_char enableDelayedAck; /* enables delayed acks */
u_char enableAlwaysAck; /* always include ack with data */
u_char enableWindowing; /* enable windowing algorithm */
uint16_t cid; /* my call id */
uint16_t peerCid; /* peer call id */
uint16_t recvWin; /* peer recv window size */
uint16_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 acknowledge‐
ments with every data packet, which is probably helpful as well.
enableWindowing enables the PPTP packet windowing mechanism speci‐
fied 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 (getconfig)
Takes two byte argument as cid and returns the current configuration
as a struct ng_pptpgre_conf.
NGM_PPTPGRE_GET_STATS (getstats)
This command returns a struct ng_pptpgre_stats containing various
node statistics.
NGM_PPTPGRE_CLR_STATS (clrstats)
This command resets the node statistics.
NGM_PPTPGRE_GETCLR_STATS (getclrstats)
This command atomically gets and resets the node statistics, return‐
ing 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.
BSD November 13, 2012 BSD