-.\" manual page [] for pppd 2.3
-.\" $Id: pppd.8,v 1.26 1997/04/30 05:56:22 paulus Exp $
+.\" manual page [] for pppd 2.4
+.\" $Id: pppd.8,v 1.60 2002/03/01 14:39:18 dfs Exp $
.\" SH section heading
.\" SS subsection heading
.\" LP paragraph
.I <tty_name>
Communicate over the named device. The string "/dev/" is prepended if
necessary. If no device name is given, or if the name of the terminal
-connected to the standard input is given, pppd
-will use that terminal, and will not fork to put itself in the
-background. This option is privileged if the \fInoauth\fR option is
-used.
+connected to the standard input is given, pppd will use that terminal,
+and will not fork to put itself in the background. A value for this
+option from a privileged source cannot be overridden by a
+non-privileged user.
.TP
.I <speed>
Set the baud rate to <speed> (a decimal number). On systems such as
4.4BSD and NetBSD, any speed can be specified. Other systems
(e.g. SunOS) allow only a limited set of speeds.
.TP
-.B active-filter \fIfilter-expression
-Specifies a packet filter to be applied to data packets to determine
-which packets are to be regarded as link activity, and therefore reset
-the idle timer, or cause the link to be brought up in demand-dialling
-mode. This option is useful in conjunction with the
-\fBidle\fR option if there are packets being sent or received
-regularly over the link (for example, routing information packets)
-which would otherwise prevent the link from ever appearing to be idle.
-The \fIfilter-expression\fR syntax is as described for tcpdump(1),
-except that qualifiers which are inappropriate for a PPP link, such as
-\fBether\fR and \fBarp\fR, are not permitted. Generally the filter
-expression should be enclosed in single-quotes to prevent whitespace
-in the expression from being interpreted by the shell. This option
-is currently only available under NetBSD, and then only
-if both the kernel and pppd were compiled with PPP_FILTER defined.
-.TP
.B asyncmap \fI<map>
Set the async character map to <map>. This map describes which
control characters cannot be successfully received over the serial
.TP
.B auth
Require the peer to authenticate itself before allowing network
-packets to be sent or received.
+packets to be sent or received. This option is the default if the
+system has a default route. If neither this option nor the
+\fInoauth\fR option is specified, pppd will only allow the peer to use
+IP addresses to which the system does not already have a route.
.TP
.B call \fIname
Read options from the file /etc/ppp/peers/\fIname\fR. This file may
.B connect \fIscript
Use the executable or shell command specified by \fIscript\fR to set
up the serial line. This script would typically use the chat(8)
-program to dial the modem and start the remote ppp session. This
-option is privileged if the \fInoauth\fR option is used.
+program to dial the modem and start the remote ppp session. A value
+for this option from a privileged source cannot be overridden by a
+non-privileged user.
.TP
.B crtscts
-Use hardware flow control (i.e. RTS/CTS) to control the flow of data
-on the serial port. If neither the \fIcrtscts\fR nor the
-\fInocrtscts\fR option is given, the hardware flow control setting
-for the serial port is left unchanged.
+Use hardware flow control (i.e. RTS/CTS) to control the flow of
+data on the serial port. If neither the \fIcrtscts\fR, the
+\fInocrtscts\fR, the \fIcdtrcts\fR nor the \fInocdtrcts\fR option
+is given, the hardware flow control setting for the serial port is
+left unchanged.
+Some serial ports (such as Macintosh serial ports) lack a true
+RTS output. Such serial ports use this mode to implement
+unidirectional flow control. The serial port will
+suspend transmission when requested by the modem (via CTS)
+but will be unable to request the modem stop sending to the
+computer. This mode retains the ability to use DTR as
+a modem control line.
.TP
.B defaultroute
Add a default route to the system routing tables, using the peer as
pppd has terminated the link. This script could, for example, issue
commands to the modem to cause it to hang up if hardware modem control
signals were not available. The disconnect script is not run if the
-modem has already hung up. This option is privileged if the
-\fInoauth\fR option is used.
+modem has already hung up. A value for this option from a privileged
+source cannot be overridden by a non-privileged user.
.TP
.B escape \fIxx,yy,...
Specifies that certain characters should be escaped on transmission
Read options from file \fIname\fR (the format is described below).
The file must be readable by the user who has invoked pppd.
.TP
+.B init \fIscript
+Run the executable or shell command specified by \fIscript\fR to
+initialize the serial line. This script would typically use the
+chat(8) program to configure the modem to enable auto answer. A value
+for this option from a privileged source cannot be overridden by a
+non-privileged user.
+.TP
.B lock
Specifies that pppd should create a UUCP-style lock file for the
serial device to ensure exclusive access to the device.
will ask the peer to send packets of no more than \fIn\fR bytes. The
minimum MRU value is 128. The default MRU value is 1500. A value of
296 is recommended for slow links (40 bytes for TCP/IP header + 256
-bytes of data).
+bytes of data). (Note that for IPv6 MRU must be at least 1280)
.TP
.B mtu \fIn
Set the MTU [Maximum Transmit Unit] value to \fIn\fR. Unless the
peer requests a smaller value via MRU negotiation, pppd will
request that the kernel networking code send data packets of no more
-than \fIn\fR bytes through the PPP network interface.
+than \fIn\fR bytes through the PPP network interface. (Note that for
+IPv6 MTU must be at least 1280)
.TP
.B passive
Enables the "passive" option in the LCP. With this option, pppd will
negotiation, unless the \fIipcp-accept-local\fR and/or
\fIipcp-accept-remote\fR options are given, respectively.
.TP
+.B ipv6 \fI<local_interface_identifier>\fR,\fI<remote_interface_identifier>
+Set the local and/or remote 64-bit interface identifier. Either one may be
+omitted. The identifier must be specified in standard ascii notation of
+IPv6 addresses (e.g. ::dead:beef). If the
+\fIipv6cp-use-ipaddr\fR
+option is given, the local identifier is the local IPv4 address (see above).
+On systems which supports a unique persistent id, such as EUI-48 derived
+from the Ethernet MAC address, \fIipv6cp-use-persistent\fR option can be
+used to replace the \fIipv6 <local>,<remote>\fR option. Otherwise the
+identifier is randomized.
+.TP
+.B active-filter \fIfilter-expression
+Specifies a packet filter to be applied to data packets to determine
+which packets are to be regarded as link activity, and therefore reset
+the idle timer, or cause the link to be brought up in demand-dialling
+mode. This option is useful in conjunction with the
+\fBidle\fR option if there are packets being sent or received
+regularly over the link (for example, routing information packets)
+which would otherwise prevent the link from ever appearing to be idle.
+The \fIfilter-expression\fR syntax is as described for tcpdump(1),
+except that qualifiers which are inappropriate for a PPP link, such as
+\fBether\fR and \fBarp\fR, are not permitted. Generally the filter
+expression should be enclosed in single-quotes to prevent whitespace
+in the expression from being interpreted by the shell. This option
+is currently only available under NetBSD, and then only
+if both the kernel and pppd were compiled with PPP_FILTER defined.
+.TP
+.B allow-ip \fIaddress(es)
+Allow peers to use the given IP address or subnet without
+authenticating themselves. The parameter is parsed as for each
+element of the list of allowed IP addresses in the secrets files (see
+the AUTHENTICATION section below).
+.TP
.B bsdcomp \fInr,nt
Request that the peer compress packets that it sends, using the
BSD-Compress scheme, with a maximum code size of \fInr\fR bits, and
compression in the corresponding direction. Use \fInobsdcomp\fR or
\fIbsdcomp 0\fR to disable BSD-Compress compression entirely.
.TP
+.B cdtrcts
+Use a non-standard hardware flow control (i.e. DTR/CTS) to control
+the flow of data on the serial port. If neither the \fIcrtscts\fR,
+the \fInocrtscts\fR, the \fIcdtrcts\fR nor the \fInocdtrcts\fR
+option is given, the hardware flow control setting for the serial
+port is left unchanged.
+Some serial ports (such as Macintosh serial ports) lack a true
+RTS output. Such serial ports use this mode to implement true
+bi-directional flow control. The sacrifice is that this flow
+control mode does not permit using DTR as a modem control line.
+.TP
.B chap-interval \fIn
If this option is given, pppd will rechallenge the peer every \fIn\fR
seconds.
Set the CHAP restart interval (retransmission timeout for challenges)
to \fIn\fR seconds (default 3).
.TP
+.B connect-delay \fIn
+Wait for up \fIn\fR milliseconds after the connect script finishes for
+a valid PPP packet from the peer. At the end of this time, or when a
+valid PPP packet is received from the peer, pppd will commence
+negotiation by sending its first LCP packet. The default value is
+1000 (1 second). This wait period only applies if the \fBconnect\fR
+or \fBpty\fR option is used.
+.TP
.B debug
Enables connection debugging facilities.
If this option is given, pppd will log the contents of all
Deflate scheme, with a maximum window size of \fI2**nr\fR bytes, and
agree to compress packets sent to the peer with a maximum window size
of \fI2**nt\fR bytes. If \fInt\fR is not specified, it defaults to
-the value given for \fInr\fR. Values in the range 8 to 15 may be used
+the value given for \fInr\fR. Values in the range 9 to 15 may be used
for \fInr\fR and \fInt\fR; larger values give better compression but
consume more kernel memory for compression dictionaries.
Alternatively, a value of 0 for \fInr\fR or \fInt\fR disables
and as the default name to send to the peer when authenticating itself
to the peer. This option is privileged.
.TP
+.B dryrun
+With the \fBdryrun\fR option, pppd will print out all the option
+values which have been set and then exit, after parsing the command
+line and options files and checking the option values, but before
+initiating the link. The option values are logged at level info, and
+also printed to standard output unless the device on standard output
+is the device that pppd would be using to communicate with the peer.
+.TP
+.B dump
+With the \fBdump\fR option, pppd will print out all the option values
+which have been set. This option is like the \fBdryrun\fR option
+except that pppd proceeds as normal rather than exiting.
+.TP
+.B endpoint \fI<epdisc>
+Sets the endpoint discriminator sent by the local machine to the peer
+during multilink negotiation to \fI<epdisc>\fR. The default is to use
+the MAC address of the first ethernet interface on the system, if any,
+otherwise the IPv4 address corresponding to the hostname, if any,
+provided it is not in the multicast or locally-assigned IP address
+ranges, or the localhost address. The endpoint discriminator can be
+the string \fBnull\fR or of the form \fItype\fR:\fIvalue\fR, where
+type is a decimal number or one of the strings \fBlocal\fR, \fBIP\fR,
+\fBMAC\fR, \fBmagic\fR, or \fBphone\fR. The value is an IP address in
+dotted-decimal notation for the \fBIP\fR type, or a string of bytes in
+hexadecimal, separated by periods or colons for the other types. For
+the MAC type, the value may also be the name of an ethernet or similar
+network interface. This option is currently only available under
+Linux.
+.TP
+.B hide-password
+When logging the contents of PAP packets, this option causes pppd to
+exclude the password string from the log. This is the default.
+.TP
.B holdoff \fIn
Specifies how many seconds to wait before re-initiating the link after
it terminates. This option only has any effect if the \fIpersist\fR
option is given, the \fIstring\fR supplied is given as the 6th
parameter to those scripts.
.TP
+.B ipv6cp-max-configure \fIn
+Set the maximum number of IPv6CP configure-request transmissions to
+\fIn\fR (default 10).
+.TP
+.B ipv6cp-max-failure \fIn
+Set the maximum number of IPv6CP configure-NAKs returned before starting
+to send configure-Rejects instead to \fIn\fR (default 10).
+.TP
+.B ipv6cp-max-terminate \fIn
+Set the maximum number of IPv6CP terminate-request transmissions to
+\fIn\fR (default 3).
+.TP
+.B ipv6cp-restart \fIn
+Set the IPv6CP restart interval (retransmission timeout) to \fIn\fR
+seconds (default 3).
+.TP
.B ipx
Enable the IPXCP and IPX protocols. This option is presently only
supported under Linux, and only if your kernel has been configured to
.TP
.B kdebug \fIn
Enable debugging code in the kernel-level PPP driver. The argument
-\fIn\fR is a number which is the sum of the following values: 1 to
+values depend on the specific kernel driver, but in general a value of
+1 will enable general kernel debug messages. (Note that these
+messages are usually only useful for debugging the kernel driver
+itself.) For the Linux 2.2.x kernel driver, the value is a sum of
+bits: 1 to
enable general debug messages, 2 to request that the contents of
received packets be printed, and 4 to request that the contents of
transmitted packets be printed. On most systems, messages printed by
the kernel are logged by syslog(1) to a file as directed in the
/etc/syslog.conf configuration file.
.TP
+.B ktune
+Enables pppd to alter kernel settings as appropriate. Under Linux,
+pppd will enable IP forwarding (i.e. set /proc/sys/net/ipv4/ip_forward
+to 1) if the \fIproxyarp\fR option is used, and will enable the
+dynamic IP address option (i.e. set /proc/sys/net/ipv4/ip_dynaddr to
+1) in demand mode if the local address changes.
+.TP
.B lcp-echo-failure \fIn
If this option is given, pppd will presume the peer to be dead
if \fIn\fR LCP echo-requests are sent without receiving a valid LCP
Set the LCP restart interval (retransmission timeout) to \fIn\fR
seconds (default 3).
.TP
+.B linkname \fIname\fR
+Sets the logical name of the link to \fIname\fR. Pppd will create a
+file named \fBppp-\fIname\fB.pid\fR in /var/run (or /etc/ppp on some
+systems) containing its process ID. This can be useful in determining
+which instance of pppd is responsible for the link to a given peer
+system. This is a privileged option.
+.TP
.B local
Don't use the modem control lines. With this option, pppd will ignore
the state of the CD (Carrier Detect) signal from the modem and will
not change the state of the DTR (Data Terminal Ready) signal.
.TP
+.B logfd \fIn
+Send log messages to file descriptor \fIn\fR. Pppd will send log
+messages to at most one file or file descriptor (as well as sending
+the log messages to syslog), so this option and the \fBlogfile\fR
+option are mutually exclusive. The default is for pppd to send log
+messages to stdout (file descriptor 1), unless the serial port is
+already open on stdout.
+.TP
+.B logfile \fIfilename
+Append log messages to the file \fIfilename\fR (as well as sending the
+log messages to syslog). The file is opened with the privileges of
+the user who invoked pppd, in append mode.
+.TP
.B login
Use the system password database for authenticating the peer using
PAP, and record the user in the system wtmp file. Note that the peer
traffic for \fIn\fR seconds (i.e. \fIn\fR seconds after the first
network control protocol comes up).
.TP
+.B maxfail \fIn
+Terminate after \fIn\fR consecutive failed connection attempts. A
+value of 0 means no limit. The default value is 10.
+.TP
.B modem
Use the modem control lines. This option is the default. With this
option, pppd will wait for the CD (Carrier Detect) signal from the
the connect script. On Ultrix, this option implies hardware flow
control, as for the \fIcrtscts\fR option.
.TP
+.B mp
+Enables the use of PPP multilink; this is an alias for the `multilink'
+option. This option is currently only available under Linux.
+.TP
+.B mpshortseq
+Enables the use of short (12-bit) sequence numbers in multilink
+headers, as opposed to 24-bit sequence numbers. This option is only
+available under Linux, and only has any effect if multilink is
+enabled (see the multilink option).
+.TP
+.B mrru \fIn
+Sets the Maximum Reconstructed Receive Unit to \fIn\fR. The MRRU is
+the maximum size for a received packet on a multilink bundle, and is
+analogous to the MRU for the individual links. This option is
+currently only available under Linux, and only has any effect if
+multilink is enabled (see the multilink option).
+.TP
.B ms-dns \fI<addr>
If pppd is acting as a server for Microsoft Windows clients, this
option allows pppd to supply one or two DNS (Domain Name Server)
instance of this option specifies the primary WINS address; the second
instance (if given) specifies the secondary WINS address.
.TP
+.B multilink
+Enables the use of the PPP multilink protocol. If the peer also
+supports multilink, then this link can become part of a bundle between
+the local system and the peer. If there is an existing bundle to the
+peer, pppd will join this link to that bundle, otherwise pppd will
+create a new bundle. See the MULTILINK section below. This option is
+currently only available under Linux.
+.TP
.B name \fIname
Set the name of the local system for authentication purposes to
\fIname\fR. This is a privileged option. With this option, pppd will
chosen based on the negotiated remote IP address; it is the
appropriate network mask for the class of the remote IP address, ORed
with the netmasks for any non point-to-point network interfaces in the
-system which are on the same network.
+system which are on the same network. (Note: on some platforms, pppd
+will always use 255.255.255.255 for the netmask, if that is the only
+appropriate value for a point-to-point interface.)
.TP
.B noaccomp
Disable Address/Control compression in both directions (send and
.TP
.B noauth
Do not require the peer to authenticate itself. This option is
-privileged if the \fIauth\fR option is specified in /etc/ppp/options.
+privileged.
.TP
.B nobsdcomp
Disables BSD-Compress compression; \fBpppd\fR will not request or
requests from pppd for CCP negotiation.
.TP
.B nocrtscts
-Disable hardware flow control (i.e. RTS/CTS) on the serial port. If
-neither the \fIcrtscts\fR nor the \fInocrtscts\fR option is given,
-the hardware flow control setting for the serial port is left
-unchanged.
+Disable hardware flow control (i.e. RTS/CTS) on the serial port.
+If neither the \fIcrtscts\fR nor the \fInocrtscts\fR nor the
+\fIcdtrcts\fR nor the \fInocdtrcts\fR option is given, the hardware
+flow control setting for the serial port is left unchanged.
+.TP
+.B nocdtrcts
+This option is a synonym for \fInocrtscts\fR. Either of these options will
+disable both forms of hardware flow control.
.TP
.B nodefaultroute
Disable the \fIdefaultroute\fR option. The system administrator who
serial device other than the terminal on the standard input is
specified, pppd will fork to become a background process.
.TP
+.B noendpoint
+Disables pppd from sending an endpoint discriminator to the peer or
+accepting one from the peer (see the MULTILINK section below). This
+option should only be required if the peer is buggy.
+.TP
.B noip
Disable IPCP negotiation and IP communication. This option should
only be required if the peer is buggy and gets confused by requests
from pppd for IPCP negotiation.
.TP
+.B noipv6
+Disable IPv6CP negotiation and IPv6 communication. This option should
+only be required if the peer is buggy and gets confused by requests
+from pppd for IPv6CP negotiation.
+.TP
.B noipdefault
Disables the default behaviour when no local IP address is specified,
which is to determine (if possible) the local IP address from the
required if the peer is buggy and gets confused by requests from pppd
for IPXCP negotiation.
.TP
+.B noktune
+Opposite of the \fIktune\fR option; disables pppd from changing system
+settings.
+.TP
+.B nolog
+Do not send log messages to a file or file descriptor. This option
+cancels the \fBlogfd\fR and \fBlogfile\fR options.
+.TP
.B nomagic
Disable magic number negotiation. With this option, pppd cannot
detect a looped-back line. This option should only be needed if the
peer is buggy.
.TP
+.B nomp
+Disables the use of PPP multilink. This option is currently only
+available under Linux.
+.TP
+.B nompshortseq
+Disables the use of short (12-bit) sequence numbers in the PPP
+multilink protocol, forcing the use of 24-bit sequence numbers. This
+option is currently only available under Linux, and only has any
+effect if multilink is enabled.
+.TP
+.B nomultilink
+Disables the use of PPP multilink. This option is currently only
+available under Linux.
+.TP
.B nopcomp
Disable protocol field compression negotiation in both the receive and
the transmit direction.
specified.
.TP
.B nopredictor1
-Do not accept or agree to Predictor-1 comprssion.
+Do not accept or agree to Predictor-1 compression.
.TP
.B noproxyarp
Disable the \fIproxyarp\fR option. The system administrator who
wishes to prevent users from creating proxy ARP entries with pppd can
do so by placing this option in the /etc/ppp/options file.
.TP
+.B notty
+Normally, pppd requires a terminal device. With this option, pppd
+will allocate itself a pseudo-tty master/slave pair and use the slave
+as its terminal device. Pppd will create a child process to act as a
+`character shunt' to transfer characters between the pseudo-tty master
+and its standard input and output. Thus pppd will transmit characters
+on its standard output and receive characters on its standard input
+even if they are not terminal devices. This option increases the
+latency and CPU overhead of transferring data over the ppp interface
+as all of the characters sent and received must flow through the
+character shunt process. An explicit device name may not be given if
+this option is used.
+.TP
.B novj
Disable Van Jacobson style TCP/IP header compression in both the
transmit and the receive direction.
.TP
.B persist
Do not exit after a connection is terminated; instead try to reopen
-the connection.
+the connection. The \fBmaxfail\fR option still has an effect on
+persistent connections.
+.TP
+.B plugin \fIfilename
+Load the shared library object file \fIfilename\fR as a plugin. This
+is a privileged option. If \fIfilename\fR does not contain a slash
+(/), pppd will look in the \fB/usr/lib/pppd/\fIversion\fR directory
+for the plugin, where
+\fIversion\fR is the version number of pppd (for example, 2.4.2).
.TP
.B predictor1
Request that the peer compress frames that it sends using Predictor-1
if requested. This option has no effect unless the kernel driver
supports Predictor-1 compression.
.TP
+.B privgroup \fIgroup-name
+Allows members of group \fIgroup-name\fR to use privileged options.
+This is a privileged option. Use of this option requires care as
+there is no guarantee that members of \fIgroup-name\fR cannot use pppd
+to become root themselves. Consider it equivalent to putting the
+members of \fIgroup-name\fR in the kmem or disk group.
+.TP
.B proxyarp
Add an entry to this system's ARP [Address Resolution Protocol] table
with the IP address of the peer and the Ethernet address of this
system. This will have the effect of making the peer appear to other
systems to be on the local ethernet.
.TP
+.B pty \fIscript
+Specifies that the command \fIscript\fR is to be used to communicate
+rather than a specific terminal device. Pppd will allocate itself a
+pseudo-tty master/slave pair and use the slave as its terminal
+device. The \fIscript\fR will be run in a child process with the
+pseudo-tty master as its standard input and output. An explicit
+device name may not be given if this option is used. (Note: if the
+\fIrecord\fR option is used in conjuction with the \fIpty\fR option,
+the child process will have pipes on its standard input and output.)
+.TP
+.B receive-all
+With this option, pppd will accept all control characters from the
+peer, including those marked in the receive asyncmap. Without this
+option, pppd will discard those characters as specified in RFC1662.
+This option should only be needed if the peer is buggy.
+.TP
+.B record \fIfilename
+Specifies that pppd should record all characters sent and received to
+a file named \fIfilename\fR. This file is opened in append mode,
+using the user's user-ID and permissions. This option is implemented
+using a pseudo-tty and a process to transfer characters between the
+pseudo-tty and the real serial device, so it will increase the latency
+and CPU overhead of transferring data over the ppp interface. The
+characters are stored in a tagged format with timestamps, which can be
+displayed in readable form using the pppdump(8) program.
+.TP
.B remotename \fIname
Set the assumed name of the remote system for authentication purposes
to \fIname\fR.
With this option, pppd will not agree to authenticate itself to the
peer using CHAP.
.TP
+.B refuse-mschap
+With this option, pppd will not agree to authenticate itself to the
+peer using MS-CHAP.
+.TP
.B refuse-pap
With this option, pppd will not agree to authenticate itself to the
peer using PAP.
Require the peer to authenticate itself using CHAP [Challenge
Handshake Authentication Protocol] authentication.
.TP
+.B require-mschap
+Require the peer to authenticate itself using MS-CHAP [Microsft Challenge
+Handshake Authentication Protocol] authentication.
+.TP
.B require-pap
Require the peer to authenticate itself using PAP [Password
Authentication Protocol] authentication.
.TP
+.B show-password
+When logging the contents of PAP packets, this option causes pppd to
+show the password string in the log message.
+.TP
.B silent
With this option, pppd will not transmit LCP packets to initiate a
connection until a valid LCP packet is received from the peer (as for
the `passive' option with ancient versions of pppd).
.TP
+.B sync
+Use synchronous HDLC serial encoding instead of asynchronous.
+The device used by pppd with this option must have sync support.
+Currently supports Microgate SyncLink adapters
+under Linux and FreeBSD 2.2.8 and later.
+.TP
+.B updetach
+With this option, pppd will detach from its controlling terminal once
+it has successfully established the ppp connection (to the point where
+the first network control protocol, usually the IP control protocol,
+has come up).
+.TP
.B usehostname
Enforce the use of the hostname (with domain name appended, if given)
as the name of the local system for authentication purposes (overrides
-the \fIname\fR option).
+the \fIname\fR option). This option is not normally needed since the
+\fIname\fR option is privileged.
+.TP
+.B usepeerdns
+Ask the peer for up to 2 DNS server addresses. The addresses supplied
+by the peer (if any) are passed to the /etc/ppp/ip-up script in the
+environment variables DNS1 and DNS2. In addition, pppd will create an
+/etc/ppp/resolv.conf file containing one or two nameserver lines with
+the address(es) supplied by the peer.
.TP
.B user \fIname
Sets the name used for authenticating the local system to the peer to
.B welcome \fIscript
Run the executable or shell command specified by \fIscript\fR before
initiating PPP negotiation, after the connect script (if any) has
-completed. This option is privileged if the \fInoauth\fR option is
-used.
+completed. A value for this option from a privileged source cannot be
+overridden by a non-privileged user.
.TP
.B xonxoff
Use software flow control (i.e. XON/XOFF) to control the flow of data on
.PP
An options file is parsed into a series of words, delimited by
whitespace. Whitespace can be included in a word by enclosing the
-word in quotes ("). A backslash (\\) quotes the following character.
+word in double-quotes ("). A backslash (\\) quotes the following character.
A hash (#) starts a comment, which continues until the end of the
line. There is no restriction on using the \fIfile\fR or \fIcall\fR
options within an options file.
provides system administrators with sufficient access control that PPP
access to a server machine can be provided to legitimate users without
fear of compromising the security of the server or the network it's
-on. In part this is provided by the /etc/ppp/options file, where the
-administrator can place options to restrict the ways in which pppd can
-be used, and in part by the PAP and CHAP secrets files, where the
-administrator can restrict the set of IP addresses which individual
-users may use.
+on. This control is provided through restrictions on which IP
+addresses the peer may use, based on its authenticated identity (if
+any), and through restrictions on which options a non-privileged user
+may use. Several of pppd's options are privileged, in particular
+those which permit potentially insecure configurations; these options
+are only accepted in files which are under the control of the system
+administrator, or if pppd is being run by root.
.PP
-The normal way that pppd should be set up is to have the \fIauth\fR
-option in the /etc/ppp/options file. (This may become the default in
-later releases.) If users wish to use pppd to dial out to a peer
-which will refuse to authenticate itself (such as an internet service
-provider), the system administrator should create an options file
-under /etc/ppp/peers containing the \fInoauth\fR option, the name of
-the serial port to use, and the \fIconnect\fR option (if required),
-plus any other appropriate options. In this way, pppd can be set up
-to allow non-privileged users to make unauthenticated connections only
-to trusted peers.
+The default behaviour of pppd is to allow an unauthenticated peer to
+use a given IP address only if the system does not already have a
+route to that IP address. For example, a system with a
+permanent connection to the wider internet will normally have a
+default route, and thus all peers will have to authenticate themselves
+in order to set up a connection. On such a system, the \fIauth\fR
+option is the default. On the other hand, a system where the
+PPP link is the only connection to the internet will not normally have
+a default route, so the peer will be able to use almost any IP address
+without authenticating itself.
.PP
As indicated above, some security-sensitive options are privileged,
which means that they may not be used by an ordinary non-privileged
an options file read using the \fIcall\fR option. If pppd is being
run by the root user, privileged options can be used without
restriction.
+.PP
+When opening the device, pppd uses either the invoking user's user ID
+or the root UID (that is, 0), depending on whether the device name was
+specified by the user or the system administrator. If the device name
+comes from a privileged source, that is, /etc/ppp/options or an
+options file read using the \fIcall\fR option, pppd uses full root
+privileges when opening the device. Thus, by creating an appropriate
+file under /etc/ppp/peers, the system administrator can allow users to
+establish a ppp connection via a device which they would not normally
+have permission to access. Otherwise pppd uses the invoking user's
+real UID when opening the device.
.SH AUTHENTICATION
Authentication is the process whereby one peer convinces the other of
its identity. This involves the first peer sending its name to the
if it has no secrets which could be used to do so.
.LP
Pppd stores secrets for use in authentication in secrets
-files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP).
+files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP/MS-CHAP).
Both secrets files have the same format. The secrets files can
contain secrets for pppd to use in authenticating itself to other
systems, as well as secrets for pppd to use when authenticating other
A secrets file is parsed into words as for a options file, so the
client name, server name and secrets fields must each be one word,
with any embedded spaces or other special characters quoted or
-escaped. Any following words on the same line are taken to be a list
-of acceptable IP addresses for that client. If there are only 3 words
-on the line, or if the first word is "-", then all IP addresses are
-disallowed. To allow any address, use "*".
-A word starting with "!" indicates that the
-specified address is \fInot\fR acceptable. An address may be followed
-by "/" and a number \fIn\fR, to indicate a whole subnet, i.e. all
-addresses which have the same value in the most significant \fIn\fR
-bits. Note that case is significant in the client and server names
+escaped. Note that case is significant in the client and server names
and in the secret.
.LP
If the secret starts with an `@', what follows is assumed to be the
server name matches any name. When selecting a secret, pppd takes the
best match, i.e. the match with the fewest wildcards.
.LP
+Any following words on the same line are taken to be a list of
+acceptable IP addresses for that client. If there are only 3 words on
+the line, or if the first word is "-", then all IP addresses are
+disallowed. To allow any address, use "*". A word starting with "!"
+indicates that the specified address is \fInot\fR acceptable. An
+address may be followed by "/" and a number \fIn\fR, to indicate a
+whole subnet, i.e. all addresses which have the same value in the most
+significant \fIn\fR bits. In this form, the address may be followed
+by a plus sign ("+") to indicate that one address from the subnet is
+authorized, based on the ppp network interface unit number in use.
+In this case, the host part of the address will be set to the unit
+number plus one.
+.LP
Thus a secrets file contains both secrets for use in authenticating
other hosts, plus secrets which we use for authenticating ourselves to
others. When pppd is authenticating the peer (checking the peer's
to the negotiated addresses. This may disrupt existing connections,
and the use of demand dialling with peers that do dynamic IP address
assignment is not recommended.
+.SH MULTILINK
+Multilink PPP provides the capability to combine two or more PPP links
+between a pair of machines into a single `bundle', which appears as a
+single virtual PPP link which has the combined bandwidth of the
+individual links. Currently, multilink PPP is only supported under
+Linux.
+.LP
+Pppd detects that the link it is controlling is connected to the same
+peer as another link using the peer's endpoint discriminator and the
+authenticated identity of the peer (if it authenticates itself). The
+endpoint discriminator is a block of data which is hopefully unique
+for each peer. Several types of data can be used, including
+locally-assigned strings of bytes, IP addresses, MAC addresses,
+randomly strings of bytes, or E-164 phone numbers. The endpoint
+discriminator sent to the peer by pppd can be set using the endpoint
+option.
+.LP
+In circumstances the peer may send no endpoint discriminator or a
+non-unique value. The optional bundle option adds an extra string
+which is added to the peer's endpoint discriminator and authenticated
+identity when matching up links to be joined together in a bundle.
+The bundle option can also be used to allow the establishment of
+multiple bundles between the local system and the peer. Pppd uses a
+TDB database in /var/run/pppd.tdb to match up links.
+.LP
+Assuming that multilink is enabled and the peer is willing to
+negotiate multilink, then when pppd is invoked to bring up the first
+link to the peer, it will detect that no other link is connected to
+the peer and create a new bundle, that is, another ppp network
+interface unit. When another pppd is invoked to bring up another link
+to the peer, it will detect the existing bundle and join its link to
+it. Currently, if the first pppd terminates (for example, because of
+a hangup or a received signal) the bundle is destroyed.
.SH EXAMPLES
.LP
The following examples assume that the /etc/ppp/options file contains
.LP
Debugging can also be enabled or disabled by sending a SIGUSR1 signal
to the pppd process. This signal acts as a toggle.
-.SH FILES
+.SH EXIT STATUS
+The exit status of pppd is set to indicate whether any error was
+detected, or the reason for the link being terminated. The values
+used are:
+.TP
+.B 0
+Pppd has detached, or otherwise the connection was successfully
+established and terminated at the peer's request.
.TP
-.B /var/run/ppp\fIn\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp\fIn\fB.pid \fR(others)
-Process-ID for pppd process on ppp interface unit \fIn\fR.
+.B 1
+An immediately fatal error of some kind occurred, such as an essential
+system call failing, or running out of virtual memory.
+.TP
+.B 2
+An error was detected in processing the options given, such as two
+mutually exclusive options being used.
+.TP
+.B 3
+Pppd is not setuid-root and the invoking user is not root.
+.TP
+.B 4
+The kernel does not support PPP, for example, the PPP kernel driver is
+not included or cannot be loaded.
+.TP
+.B 5
+Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP
+signal.
+.TP
+.B 6
+The serial port could not be locked.
+.TP
+.B 7
+The serial port could not be opened.
+.TP
+.B 8
+The connect script failed (returned a non-zero exit status).
+.TP
+.B 9
+The command specified as the argument to the \fIpty\fR option could
+not be run.
+.TP
+.B 10
+The PPP negotiation failed, that is, it didn't reach the point where
+at least one network protocol (e.g. IP) was running.
+.TP
+.B 11
+The peer system failed (or refused) to authenticate itself.
+.TP
+.B 12
+The link was established successfully and terminated because it was
+idle.
+.TP
+.B 13
+The link was established successfully and terminated because the
+connect time limit was reached.
+.TP
+.B 14
+Callback was negotiated and an incoming call should arrive shortly.
+.TP
+.B 15
+The link was terminated because the peer is not responding to echo
+requests.
+.TP
+.B 16
+The link was terminated by the modem hanging up.
+.TP
+.B 17
+The PPP negotiation failed because serial loopback was detected.
+.TP
+.B 18
+The init script failed (returned a non-zero exit status).
+.TP
+.B 19
+We failed to authenticate ourselves to the peer.
+.SH SCRIPTS
+Pppd invokes scripts at various stages in its processing which can be
+used to perform site-specific ancillary processing. These scripts are
+usually shell scripts, but could be executable code files instead.
+Pppd does not wait for the scripts to finish. The scripts are
+executed as root (with the real and effective user-id set to 0), so
+that they can do things such as update routing tables or run
+privileged daemons. Be careful that the contents of these scripts do
+not compromise your system's security. Pppd runs the scripts with
+standard input, output and error redirected to /dev/null, and with an
+environment that is empty except for some environment variables that
+give information about the link. The environment variables that pppd
+sets are:
+.TP
+.B DEVICE
+The name of the serial tty device being used.
+.TP
+.B IFNAME
+The name of the network interface being used.
+.TP
+.B IPLOCAL
+The IP address for the local end of the link. This is only set when
+IPCP has come up.
+.TP
+.B IPREMOTE
+The IP address for the remote end of the link. This is only set when
+IPCP has come up.
+.TP
+.B PEERNAME
+The authenticated name of the peer. This is only set if the peer
+authenticates itself.
+.TP
+.B SPEED
+The baud rate of the tty device.
+.TP
+.B ORIG_UID
+The real user-id of the user who invoked pppd.
+.TP
+.B PPPLOGNAME
+The username of the real user-id that invoked pppd. This is always set.
+.P
+For the ip-down and auth-down scripts, pppd also sets the following
+variables giving statistics for the connection:
+.TP
+.B CONNECT_TIME
+The number of seconds from when the PPP negotiation started until the
+connection was terminated.
+.TP
+.B BYTES_SENT
+The number of bytes sent (at the level of the serial port) during the
+connection.
+.TP
+.B BYTES_RCVD
+The number of bytes received (at the level of the serial port) during
+the connection.
+.TP
+.B LINKNAME
+The logical name of the link, set with the \fIlinkname\fR option.
+.P
+Pppd invokes the following scripts, if they exist. It is not an error
+if they don't exist.
.TP
.B /etc/ppp/auth-up
A program or script which is executed after the remote system
.IP
\fIinterface-name peer-name user-name tty-device speed\fR
.IP
-and with its standard input, output and error redirected to
-/dev/null. This program or script is executed with the real and
-effective user-IDs set to root, and with an empty environment. (Note
-that this script is not executed if the peer doesn't authenticate
-itself, for example when the \fInoauth\fR option is used.)
+Note that this script is not executed if the peer doesn't authenticate
+itself, for example when the \fInoauth\fR option is used.
.TP
.B /etc/ppp/auth-down
A program or script which is executed when the link goes down, if
.IP
\fIinterface-name tty-device speed local-IP-address
remote-IP-address ipparam\fR
-.IP
-and with its standard input,
-output and error streams redirected to /dev/null.
-.IP
-This program or script is executed with the real and effective
-user-IDs set to root. This is so that it can be used to manipulate
-routes, run privileged daemons (e.g. \fIsendmail\fR), etc. Be
-careful that the contents of the /etc/ppp/ip-up and /etc/ppp/ip-down
-scripts do not compromise your system's security.
-.IP
-This program or script is executed with an empty environment, so you
-must either specify a PATH or use full pathnames.
.TP
.B /etc/ppp/ip-down
A program or script which is executed when the link is no longer
available for sending and receiving IP packets. This script can be
used for undoing the effects of the /etc/ppp/ip-up script. It is
invoked in the same manner and with the same parameters as the ip-up
-script, and the same security considerations apply.
+script.
+.TP
+.B /etc/ppp/ipv6-up
+Like /etc/ppp/ip-up, except that it is executed when the link is available
+for sending and receiving IPv6 packets. It is executed with the parameters
+.IP
+\fIinterface-name tty-device speed local-link-local-address
+remote-link-local-address ipparam\fR
+.TP
+.B /etc/ppp/ipv6-down
+Similar to /etc/ppp/ip-down, but it is executed when IPv6 packets can no
+longer be transmitted on the link. It is executed with the same parameters
+as the ipv6-up script.
.TP
.B /etc/ppp/ipx-up
A program or script which is executed when the link is available for
remote-IPX-node-address local-IPX-routing-protocol remote-IPX-routing-protocol
local-IPX-router-name remote-IPX-router-name ipparam pppd-pid\fR
.IP
-and with its standard input,
-output and error streams redirected to /dev/null.
-.br
-.IP
The local-IPX-routing-protocol and remote-IPX-routing-protocol field
may be one of the following:
.IP
NLSP to indicate that Novell NLSP should be used
.br
RIP NLSP to indicate that both RIP/SAP and NLSP should be used
-.br
-.IP
-This program or script is executed with the real and effective
-user-IDs set to root, and with an empty environment. This is so
-that it can be used to manipulate routes, run privileged daemons (e.g.
-\fIripd\fR), etc. Be careful that the contents of the /etc/ppp/ipx-up
-and /etc/ppp/ipx-down scripts do not compromise your system's
-security.
.TP
.B /etc/ppp/ipx-down
A program or script which is executed when the link is no longer
available for sending and receiving IPX packets. This script can be
used for undoing the effects of the /etc/ppp/ipx-up script. It is
invoked in the same manner and with the same parameters as the ipx-up
-script, and the same security considerations apply.
+script.
+.SH FILES
+.TP
+.B /var/run/ppp\fIn\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp\fIn\fB.pid \fR(others)
+Process-ID for pppd process on ppp interface unit \fIn\fR.
+.TP
+.B /var/run/ppp-\fIname\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp-\fIname\fB.pid \fR(others)
+Process-ID for pppd process for logical link \fIname\fR (see the
+\fIlinkname\fR option).
.TP
.B /etc/ppp/pap-secrets
Usernames, passwords and IP addresses for PAP authentication. This
user. Pppd will log a warning if this is not the case.
.TP
.B /etc/ppp/chap-secrets
-Names, secrets and IP addresses for CHAP authentication. As for
+Names, secrets and IP addresses for CHAP/MS-CHAP authentication. As for
/etc/ppp/pap-secrets, this file should be owned by root and not
readable or writable by any other user. Pppd will log a warning if
this is not the case.
Simpson, W.A.
.I PPP in HDLC-like Framing.
July 1994.
+.TP
+.B RFC2472
+Haskin, D.
+.I IP Version 6 over PPP
+December 1998.
.SH NOTES
The following signals have the specified effect when sent to pppd.
.TP
projects / ppp.git / blobdiff