.TH PPP 8
.SH NAME
ppp, pppoe, pptp, pptpd \- point to point protocol
.SH SYNOPSIS
.B ip/ppp
[
.B -CPScdfu
] [
.B -b
.I baud
] [
.B -k
.I keyspec
] [
.B -m
.I mtu
] [
.B -M
.I chatfile
] [
.B -p
.I dev
] [
.B -x
.I netmntpt
] [
.B -t
.I modemcmd
] [
.I local
[
.I remote
] ]
.PP
.B ip/pppoe
[
.B -Pd
]
[
.B -A
.I acname
]
[
.B -S
.I srvname
]
[
.B -k
.I keyspec
]
[
.B -m
.I mtu
]
[
.B -x
.I pppnetmntpt
]
[
.I ether
]
.PP
.B ip/pptp
[
.B -dP
]
[
.B -k
.I keyspec
]
[
.B -w
.I window
]
[
.B -x
.I pppnetmntpt
]
.I server
.PP
.B ip/pptpd
[
.B -d
] [
.B -p
.I pppnetmtpt
] [
.B -w
.I window
] [
.B -D
.I fraction
]
.I tcp-dir
.SH DESCRIPTION
The Point to Point Protocol is used to encapsulate Internet Protocol packets
for transfer over serial lines or other protocol connections.
.I Ppp
can run either as a client or, with the
.I \-S
option, as a server.  The only differences between a client and a server is
that the server will not believe any local address the client tries to
supply it and that the server always initiates the authentication of the
client.
.PP
With no option,
.I ppp
communicates with the remote system via standard input and output.
This is useful if a program wants to use
.I ppp
in a communications stream.  However, the normal mode is to
specify a communications device, usually a serial line with a modem.
.PP
PPP supports the following options:
.TP
.B b
set the baud rate on the communications device
.TP
.B f
make PPP add HDLC framing.  This is necessary when using
PPP over a serial line or a TCP connection
.TP
.B k
add
.I keyspec
to the
.IR factotum (4)
key pattern when looking for a user name and password
for authentication; the default key pattern is
.B "proto=pass" "service=ppp"
.TP
.B m
set the maximum transfer unit (default 1450)
.TP
.B P
use this as the primary IP interface; set the default
route through this interface and write its configuration
to
.B /net/ndb
.TP
.B p
communicate over
.I dev
instead of standard I/O
.TP
.B u
before starting the PPP protocol with the remote end, shuttle
bytes between the device and standard I/O until an EOF on standard
input.  This allows a user to start
.I ppp
and then type commands at a modem before
.I ppp
takes over
.TP
.B S
run as a server
.TP
.B t
before starting the PPP protocol, write
.I modemcmd
to the device
.TP
.B x
use the IP stack mounted at
.I netmntpt
.TP
.B M
chat with the modem as specified in the chat file.  Each line in
the chat file contains a string that is transmitted to the modem
and the response expected (e.g. 'AT' 'OK')
.TP
.B c
disallow packet compression
.TP
.B C
disallow ip header compression
.PD
.PP
If both the
.I local
and
.I remote
addresses are specified, don't ask the other end for either
or believe it if it supplies one.  If either is missing, get
it from the remote end.
.PP
.I Pppoe
is a PPP over ethernet (PPPoE) client.
It invokes
.I ppp
to start a PPP conversation which is
tunneled in PPPoE packets on 
the ethernet device mounted at 
.I etherdir
(default
.BR /net/ether0 ).
The 
.I pppoe -specific
options are:
.TP
.B A
insist on an access concentrator named
.I acname
during PPPoE discovery
.TP
.B S
insist on a service named
.I srvname
during PPPoE discovery
.TP
.B d
write debugging output to standard error,
and pass
.B -d
to 
.I ppp
.PD
.PP
The other options are relayed to 
.IR ppp .
.PP
.I Pptp
is a client for a PPTP encrypted tunnel.
.I Server
is the name of the server to dial.
.I Pptp
takes the same options as
.IR pppoe ,
except for the lack of a
.B -m
option and the addition of a
.B -w
option.
The
.B -w
option specifies the local send window size
(default 16) in packets.
.PP
.I Pptpd
is the server side of a PPTP encrypted tunnel.
.I Tcpdir
is the directory of a TCP connection to the client.
The TCP connection is used to control the tunnel while
packets are sent back and forth using PPP inside of
GRE packets.
The options are:
.TP
.B d
write debugging output to standard error.
.TP
.B p
use the IP stack mounted at
.I pppnetmtpt
to terminate the PPP connection.
.TP
.B w
set the receive window to
.IR window .
.TP
.B D
drop
.I fraction
of the received packets.  This is used for testing.
.PD
.SH SOURCE
.B /sys/src/cmd/ip/ppp
.br
.B /sys/src/cmd/ip/pptpd.c
.br
.B /sys/src/cmd/ip/pppoe.c
.SH BUGS
.I Ppp
should use factotum to execute
the client side of the challenge-reponse
protocol, but instead it reads a password
from factotum and runs the protocol itself.