ppp, pppoe, pptp, pptpd - point-to-point protocol
ip/ppp [ -CPSacdfu ] [ -b baud ] [ -k keyspec ] [ -m mtu ] [ -M chat‐
file ] [ -p dev ] [ -x netmntpt ] [ -t modemcmd ] [ local [ remote ] ]
ip/pppoe [ -Pd ] [ -A acname ] [ -S srvname ] [ -k keyspec ] [ -m mtu ]
[ -x pppnetmntpt ] [ ether ]
ip/pptp [ -dP ] [ -k keyspec ] [ -w window ] [ -x pppnetmntpt ] server
ip/pptpd [ -d ] [ -p pppnetmtpt ] [ -w window ] [ -D fraction ] tcp-dir
The Point-to-Point Protocol is used to encapsulate Internet Protocol
packets in IPv4 packets for transfer over serial lines or other proto‐
col connections. Ppp can run either as a client or, with the -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 authentica‐
tion of the client.
With no option, ppp communicates with the remote system via standard
input and output. This is useful if a program wants to use ppp in a
communications stream. However, the normal mode is to specify a commu‐
nications device, usually a serial line with a modem.
Ppp supports the following options:
a as server, don't request authentication from the client
b set the baud rate on the communications device
c disallow packet compression
C disallow IP header compression
f make PPP add HDLC framing. This is necessary when using PPP over a
serial line or a TCP connection
k add keyspec to the factotum(4) key pattern when looking for a user
name and password for authentication; the default key pattern is
m set the maximum transfer unit (default 1450)
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')
P use this as the primary IP interface; set the default route through
this interface and write its configuration to /net/ndb
p communicate over dev instead of standard I/O
S run as a server
t before starting the PPP protocol, write modemcmd to the device
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 ppp and then type commands at a modem
before ppp takes over
x use the IP stack mounted at netmntpt
If both the local and 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.
Pppoe is a PPP over ethernet (PPPoE) client. It invokes ppp to start a
PPP conversation which is tunneled in PPPoE packets on the ethernet
device mounted at etherdir (default /net/ether0). The pppoe-specific
A insist on an access concentrator named acname during PPPoE discovery
d write debugging output to standard error, and pass -d to ppp
S insist on a service named srvname during PPPoE discovery
The other options are relayed to ppp.
Pptp is a client for a PPTP encrypted tunnel. Server is the name of
the server to dial. Pptp takes the same options as pppoe, except for
the lack of a -m option and the addition of a -w option. The -w option
specifies the local send window size (default 16) in packets.
Pptpd is the server side of a PPTP encrypted tunnel. 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:
d write debugging output to standard error.
D drop fraction of the received packets. This is used for testing.
p use the IP stack mounted at pppnetmtpt to terminate the PPP connec‐
w set the receive window to window.
gre in ip(3)BUGS
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.