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 recognised 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.

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

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

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

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 mppe-40 mppe-128 mppe-stateless name domain\\\\username remotename PPTP require-chapms-v2 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 performance 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 system 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-linux

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>.