PPTP(8) 						      System Manager's Manual							   PPTP(8)

NAME

       pptp - PPTP driver

SYNOPSIS

       pptp <pptp-server-IP> <pptp-options> [ppp-options] ...

DESCRIPTION

       pptp  establishes  the client side of a Virtual Private Network (VPN) using the Point-to-Point Tunneling Protocol (PPTP).  Use this program
       to connect to an employer's PPTP based VPN, or to certain cable and ADSL service providers.

       By default, pptp establishes the PPTP call to the PPTP server, and then starts an instance of pppd to manage the data  transfer.   However,
       pptp can also be run as a connection manager within pppd.

OPTIONS

       The first non-option argument on the pptp command line must be the host name or IP address of the PPTP server.

       All long options (starting with "--") are interpreted as pptp options, and a fatal error occurs if an unrecognised option is used.

       All  command-line  arguments  which do not start with "-" are interpreted as ppp options, and passed as is to pppd unless --nolaunchpppd is
       given.

       --phone <number>
	      Pass <number> to remote host as phone number

       --nolaunchpppd
	      Do not launch pppd but use stdin as the network connection.  Use this flag when including pptp as a pppd	connection  process  using
	      the pty option.  See EXAMPLES.

       --quirks <quirk>
	      Work around a buggy PPTP implementation, adopts special case handling for particular PPTP servers and ADSL modems.  Currently recog-
	      nised values are BEZEQ_ISRAEL only

       --debug
	      Run in foreground (for debugging with gdb)

       --sync Enable Synchronous HDLC (pppd must use it too)

       --timeout <secs>
	      Time to wait for reordered packets (0.01 to 10 secs)

       --nobuffer
	      Completely disables buffering and reordering of packets.	Any --timeout specified will be ignored.

       --idle-wait <secs>
	      Time to wait before sending a control connection echo request.  The RFC2637 default is 60 seconds.

       --max-echo-wait <secs>
	      Time to wait for an echo reply before closing the control connection.  The RFC2637 default is 60 seconds.

       --logstring <name>
	      Use <name> instead of 'anon' in syslog messages

       --localbind <addr>
	      Bind to specified IP address instead of wildcard

       --rtmark <n>
	      Use specified policy routing mark for all packets.  This causes both the TCP control connection's packets as well as the GRE packets
	      to bear the given policy routing / netfilter mark. This can be used with ip rule (from iproute2) to use a separate routing table for
	      the pptp client.

	      (requires root privileges or the CAP_NET_ADMIN capability.)

       --nohostroute
	      Do not configure a host route pointing towards the PPTP server.  (cf. ROUTING below)

       --loglevel <level>
	      Sets the debugging level (0=low, 1=default, 2=high)

       --test-type <n>
	      Enable packet reordering tests that damage the integrity of the packet stream to the server.  Use this only  when  testing  servers.
	      Zero  is	the  default,  and  means that packets are sent in the correct order.  A value of one (1) causes a single swap between two
	      packets, such that the sequence numbers might be 1 2 3 4 6 5 7 8 9.  A value of two (2) causes ten packets to be buffered, then sent
	      out  of  order  but ascending, such that the sequence numbers might be 1 2 3 4 16 6 7 8 9 10 11 12 13 14 15 17 18 19 20.	A value of
	      three (3) causes ten packets to be buffered, then sent in the reverse order, like this; 1 2 3 4 16 15 14 13 12 11 10 9 8 7 6 5 17 18
	      19 20.

       --test-rate <n>
	      Sets  the  number  of  packets  to pass before causing a reordering test.  Default is 100.  Has no effect if test-type is zero.  The
	      result of test types 2 and 3 are undefined if this value is less than ten.

ROUTING

       When PPTP is used in conjunction with a default route on top of the tunnel (or just any route encompassing the PPTP server), the  mechanics
       of  routing  would  cause  the PPTP packets themselves to be routed over the tunnel. This would result in an encapsulation loop, destroying
       connectivity.

       pptp by default works around this by looking up the route towards the PPTP server at startup and configures a host route  with  that  data.
       This  essentially  "freezes"  routing  for  PPTP packets at the startup configuration. This behaviour can be disabled with --nohostroute if
       undesired (like when using --rtmark to implement policy routing).

       NB: the route added by pptp is currently not deleted at exit!

QUIRKS

       BEZEQ_ISRAEL
	      modifies packets to interoperate with Orckit ADSL modems on the BEZEQ network in Israel.

EXAMPLES

       Connection to a Microsoft Windows VPN Server

	pppd noauth nobsdcomp nodeflate require-mppe-128 name domain\\username remotename PPTP pty "pptp 10.0.0.5 --nolaunchpppd"

       Note that the chap-secrets file used by pppd must include an entry for domain\username

STATISTICS

       The pptp process collects statistics when sending and receiving GRE packets. They are intended to be useful for debugging poor PPTP perfor-
       mance and for general monitoring of link quality. The statistics are cumulative since the pptp process was started.

       The  statistics can be viewed by sending a SIGUSR1 signal to the "GRE-to-PPP Gateway" process, which will cause it to dump them to the sys-
       tem logs (at the LOG_NOTICE level). A better way to present the statistics to applications is being sought (e.g. SNMP?).

       The following statistics are collected at the time of writing (April 2003):

       rx accepted
	      the number of GRE packets successfully passed to PPP

       rx lost
	      the number of packets never received, and presumed lost in the network

       rx under win
	      the number of packets which were duplicates or had old sequence numbers (this might be caused by a packet-reordering network if your
	      reordering timeout is set too low)

       rx over win
	      the  number of packets which were too far ahead in the sequence to be reordered (might be caused by loss of more than 300 packets in
	      a row)

       rx buffered
	      the number of packets which were slightly ahead of sequence, and were either buffered for reordering, or if buffering  is  disabled,
	      accepted immediately (resulting in the intermediate packets being discarded).

       rx OS errors
	      the number of times where the operating system reported an error when we tried to read a packet

       rx truncated
	      the number of times we received a packet which was shorter than the length implied by the GRE header

       rx invalid
	      the number of times we received a packet which had invalid or unsupported flags set in the header, wrong version, or wrong protocol.

       rx acks
	      the  number  of pure acknowledgements received (without data). Too many of these will waste bandwidth, and might be solved by tuning
	      the remote host.

       tx sent
	      the number of GRE packets sent with data

       tx failed
	      the number of packets we tried to send, but the OS reported an error

       tx short
	      the number of times the OS would not let us write a complete packet

       tx acks
	      the number of times we sent a pure ack, without data

       tx oversize
	      the number of times we couldn't send a packet because it was over PACKET_MAX bytes long

       round trip
	      the estimated round-trip time in milliseconds

SEE ALSO

       pppd(8)

       Documentation in /usr/share/doc/pptp

AUTHOR

       This manual page was written by James Cameron <james.cameron@hp.com> from text contributed by Thomas Quinot  <thomas@debian.org>,  for  the
       Debian GNU/Linux system.  The description of the available statistics was written by Chris Wilson <chris@netservers.co.uk>. Updates for the
       Debian distribution by Ola Lundqvist <opal@debian.org>.

																	   PPTP(8)