-.\" manual page [] for pppd 2.0
-.\" $Id: pppd.8,v 1.19 1996/07/01 01:19:01 paulus Exp $
+.\" manual page [] for pppd 2.3
+.\" $Id: pppd.8,v 1.38 1999/03/30 06:33:09 paulus Exp $
.\" SH section heading
.\" SS subsection heading
.\" LP paragraph
and configuring different network-layer protocols.
.LP
The encapsulation scheme is provided by driver code in the kernel.
-.B pppd
-provides the basic LCP, authentication support, and an
-NCP for establishing and configuring the Internet Protocol (IP)
-(called the IP Control Protocol, IPCP).
+Pppd provides the basic LCP, authentication support, and an NCP for
+establishing and configuring the Internet Protocol (IP) (called the IP
+Control Protocol, IPCP).
.SH FREQUENTLY USED OPTIONS
.TP
.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 controlling terminal is given,
-.I pppd
-will use the controlling terminal, and will not fork to put itself in
-the background.
+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. 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
(e.g. SunOS) allow only a limited set of speeds.
.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 line.
-.I pppd
-will ask the peer to send these characters as a 2-byte escape sequence.
-The argument is a 32 bit hex number
-with each bit representing a character to escape.
-Bit 0 (00000001) represents the character 0x00;
-bit 31 (80000000) represents the character 0x1f or ^_.
-If multiple \fBasyncmap\fR options are
-given, the values are ORed together.
-If no \fBasyncmap\fR option is given, no async character map will be
-negotiated for the receive direction; the peer should then escape
-\fIall\fR control characters.
+Set the async character map to <map>. This map describes which
+control characters cannot be successfully received over the serial
+line. Pppd will ask the peer to send these characters as a 2-byte
+escape sequence. The argument is a 32 bit hex number with each bit
+representing a character to escape. Bit 0 (00000001) represents the
+character 0x00; bit 31 (80000000) represents the character 0x1f or ^_.
+If multiple \fIasyncmap\fR options are given, the values are ORed
+together. If no \fIasyncmap\fR option is given, no async character
+map will be negotiated for the receive direction; the peer should then
+escape \fIall\fR control characters. To escape transmitted
+characters, use the \fIescape\fR option.
.TP
.B auth
Require the peer to authenticate itself before allowing network
-packets to be sent or received.
-.TP
-.B connect \fI<p>
-Use the executable or shell command specified by \fI<p>\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.
+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
+contain privileged options, such as \fInoauth\fR, even if pppd
+is not being run by root. The \fIname\fR string may not begin with /
+or include .. as a pathname component. The format of the options file
+is described below.
+.TP
+.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. 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 \fBcrtscts\fR nor the
-\fB\-crtscts\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 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 defaultroute
Add a default route to the system routing tables, using the peer as
the gateway, when IPCP negotiation is successfully completed.
-This entry is removed when the PPP connection is broken.
+This entry is removed when the PPP connection is broken. This option
+is privileged if the \fInodefaultroute\fR option has been specified.
.TP
-.B disconnect \fI<p>
-Run the executable or shell command specified by \fI<p>\fR after
-\fIpppd\fR 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.
+.B disconnect \fIscript
+Run the executable or shell command specified by \fIscript\fR after
+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. 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
(regardless of whether the peer requests them to be escaped with its
async control character map). The characters to be escaped are
specified as a list of hex numbers separated by commas. Note that
-almost any character can be specified for the \fBescape\fR option,
-unlike the \fBasyncmap\fR option which only allows control characters
+almost any character can be specified for the \fIescape\fR option,
+unlike the \fIasyncmap\fR option which only allows control characters
to be specified. The characters which may not be escaped are those
with hex values 0x20 - 0x3f or 0x5e.
.TP
-.B file \fI<f>
-Read options from file <f> (the format is described below).
+.B file \fIname
+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 lock
-Specifies that \fIpppd\fR should create a UUCP-style lock file for the
+Specifies that pppd should create a UUCP-style lock file for the
serial device to ensure exclusive access to the device.
.TP
-.B mru \fI<n>
-Set the MRU [Maximum Receive Unit] value to <n> for negotiation.
-.I pppd
-will ask the peer to send packets of no more than <n> bytes. The
+.B mru \fIn
+Set the MRU [Maximum Receive Unit] value to \fIn\fR. Pppd
+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).
.TP
-.B mtu \fI<n>
-Set the MTU [Maximum Transmit Unit] value to \fI<n>\fR. Unless the
-peer requests a smaller value via MRU negotiation, \fIpppd\fR will
+.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.
.TP
.B passive
-Enables the "passive" option in the LCP. With this option,
-.I pppd
-will attempt to initiate a connection; if no reply is received from
-the peer,
-.I pppd
-will then just wait passively for a valid LCP packet from the peer
-(instead of exiting, as it does without this option).
+Enables the "passive" option in the LCP. With this option, pppd will
+attempt to initiate a connection; if no reply is received from the
+peer, pppd will then just wait passively for a valid LCP packet from
+the peer, instead of exiting, as it would without this option.
.SH OPTIONS
.TP
.I <local_IP_address>\fB:\fI<remote_IP_address>
omitted. The IP addresses can be specified with a host name or in
decimal dot notation (e.g. 150.234.56.78). The default local
address is the (first) IP address of the system (unless the
-.B noipdefault
+\fInoipdefault\fR
option is given). The remote address will be obtained from the peer
if not specified in any option. Thus, in simple cases, this option is
not required. If a local and/or remote IP address is specified with
-this option,
-.I pppd
+this option, pppd
will not accept a different value from the peer in the IPCP
-negotiation, unless the
-.B ipcp-accept-local
-and/or
-.B ipcp-accept-remote
-options are given, respectively.
+negotiation, unless the \fIipcp-accept-local\fR and/or
+\fIipcp-accept-remote\fR options are given, respectively.
.TP
.B active-filter \fIfilter-expression
Specifies a packet filter to be applied to data packets to determine
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.
+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 bsdcomp \fInr,nt
Request that the peer compress packets that it sends, using the
\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
-compression in the corresponding direction.
+compression in the corresponding direction. Use \fInobsdcomp\fR or
+\fIbsdcomp 0\fR to disable BSD-Compress compression entirely.
.TP
-.B chap-interval \fI<n>
-If this option is given,
-.I pppd
-will rechallenge the peer every <n> seconds.
+.B chap-interval \fIn
+If this option is given, pppd will rechallenge the peer every \fIn\fR
+seconds.
.TP
-.B chap-max-challenge \fI<n>
-Set the maximum number of CHAP challenge transmissions to <n> (default
-10).
+.B chap-max-challenge \fIn
+Set the maximum number of CHAP challenge transmissions to \fIn\fR
+(default 10).
.TP
-.B chap-restart \fI<n>
+.B chap-restart \fIn
Set the CHAP restart interval (retransmission timeout for challenges)
-to <n> seconds (default 3).
+to \fIn\fR seconds (default 3).
.TP
.B debug
-Increase debugging level.
-If this option is given, \fIpppd\fR will log the contents of all
+Enables connection debugging facilities.
+If this option is given, pppd will log the contents of all
control packets sent or received in a readable form. The packets are
logged through syslog with facility \fIdaemon\fR and level
\fIdebug\fR. This information can be directed to a file by setting up
.TP
.B default-mru
Disable MRU [Maximum Receive Unit] negotiation. With this option,
-\fIpppd\fR will use the default MRU value of 1500 bytes for both the
+pppd will use the default MRU value of 1500 bytes for both the
transmit and receive direction.
.TP
.B deflate \fInr,nt
Request that the peer compress packets that it sends, using the
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 for
-\fInr\fR and \fInt\fR; larger values give better compression but
+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
+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
-compression in the corresponding direction. (Note: \fBpppd\fR
-requests Deflate compression in preference to BSD-Compress
-if the peer can do either.)
+compression in the corresponding direction. Use \fInodeflate\fR or
+\fIdeflate 0\fR to disable Deflate compression entirely. (Note: pppd
+requests Deflate compression in preference to BSD-Compress if the peer
+can do either.)
.TP
.B demand
Initiate the link only on demand, i.e. when data traffic is present.
-With this option, the remote IP address must be specific by the user
-on the command line or in an options file. \fBpppd\fR will initially
+With this option, the remote IP address must be specified by the user
+on the command line or in an options file. Pppd will initially
configure the interface and enable it for IP traffic without
-connecting to the peer. When traffic is available, \fBpppd\fR will
+connecting to the peer. When traffic is available, pppd will
connect to the peer and perform negotiation, authentication, etc.
-When this is completed, \fBpppd\fR will commence passing data packets
-(i.e., IP packets) across the link. The persist, idle and holdoff
-options are often useful in conjuction with this option.
-.TP
-.B domain \fI<d>
-Append the domain name <d> to the local host name for authentication
-purposes. For example, if gethostname() returns the name porsche, but the
-fully qualified domain name is porsche.Quotron.COM, you would use the
-domain option to set the domain name to Quotron.COM.
-.TP
-.B holdoff \fI<n>
+When this is completed, pppd will commence passing data packets
+(i.e., IP packets) across the link.
+
+The \fIdemand\fR option implies the \fIpersist\fR option. If this
+behaviour is not desired, use the \fInopersist\fR option after the
+\fIdemand\fR option. The \fIidle\fR and \fIholdoff\fR
+options are also useful in conjuction with the \fIdemand\fR option.
+.TP
+.B domain \fId
+Append the domain name \fId\fR to the local host name for authentication
+purposes. For example, if gethostname() returns the name porsche, but
+the fully qualified domain name is porsche.Quotron.COM, you could
+specify \fIdomain Quotron.COM\fR. Pppd would then use the name
+\fIporsche.Quotron.COM\fR for looking up secrets in the secrets file,
+and as the default name to send to the peer when authenticating itself
+to the peer. This option is privileged.
+.TP
+.B hide-password
+When logging the contents of PAP packets, this option causes pppd to
+exclude the password string from the log.
+.TP
+.B holdoff \fIn
Specifies how many seconds to wait before re-initiating the link after
-it terminates. This option only has effect if the persist option is
-used.
-.TP
-.B idle \fI<n>
-Specifies that \fBpppd\fR should disconnect if it is idle for
-\fI<n>\fR seconds. The link is idle when no data packets (i.e. IP
-packets) are being sent or received. If the \fBactive-filter\fR
+it terminates. This option only has any effect if the \fIpersist\fR
+or \fIdemand\fR option is used. The holdoff period is not applied if
+the link was terminated because it was idle.
+.TP
+.B idle \fIn
+Specifies that pppd should disconnect if the link is idle for \fIn\fR
+seconds. The link is idle when no data packets (i.e. IP packets) are
+being sent or received. Note: it is not advisable to use this option
+with the \fIpersist\fR option without the \fIdemand\fR option.
+If the \fBactive-filter\fR
option is given, data packets which are rejected by the specified
activity filter also count as the link being idle.
.TP
-.B ipx
-Enable the IPXCP and IPX protocols. Under Linux, this is the default
-condition if your kernel supports IPX. This option is presently only
-supported under Linux.
-.TP
.B ipcp-accept-local
-With this option,
-.I pppd
-will accept the peer's idea of our local IP address, even if the
-local IP address was specified in an option.
+With this option, pppd will accept the peer's idea of our local IP
+address, even if the local IP address was specified in an option.
.TP
.B ipcp-accept-remote
-With this option,
-.I pppd
-will accept the peer's idea of its (remote) IP address, even if the
-remote IP address was specified in an option.
+With this option, pppd will accept the peer's idea of its (remote) IP
+address, even if the remote IP address was specified in an option.
.TP
-.B ipcp-max-configure \fI<n>
-Set the maximum number of IPCP configure-request transmissions to <n>
-(default 10).
+.B ipcp-max-configure \fIn
+Set the maximum number of IPCP configure-request transmissions to
+\fIn\fR (default 10).
.TP
-.B ipcp-max-failure \fI<n>
+.B ipcp-max-failure \fIn
Set the maximum number of IPCP configure-NAKs returned before starting
-to send configure-Rejects instead to <n> (default 10).
+to send configure-Rejects instead to \fIn\fR (default 10).
.TP
-.B ipcp-max-terminate \fI<n>
-Set the maximum number of IPCP terminate-request transmissions to <n>
-(default 3).
+.B ipcp-max-terminate \fIn
+Set the maximum number of IPCP terminate-request transmissions to
+\fIn\fR (default 3).
.TP
-.B ipcp-restart \fI<n>
-Set the IPCP restart interval (retransmission timeout) to <n> seconds
-(default 3).
+.B ipcp-restart \fIn
+Set the IPCP restart interval (retransmission timeout) to \fIn\fR
+seconds (default 3).
.TP
.B ipparam \fIstring
Provides an extra parameter to the ip-up and ip-down scripts. If this
option is given, the \fIstring\fR supplied is given as the 6th
parameter to those scripts.
.TP
-.B ipx-network \fI<n>
+.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
+include IPX support.
+.TP
+.B ipx-network \fIn
Set the IPX network number in the IPXCP configure request frame to
-<n>. There is no valid default. If this option is not specified then
-the network number is obtained from the peer. If the peer does not
-have the network number, the IPX protocol will not be started. This is
-a hexadecimal number and is entered without any leading sequence such
-as 0x. It is related to the \fIipxcp-accept-network\fR option.
+\fIn\fR, a hexadecimal number (without a leading 0x). There is no
+valid default. If this option is not specified, the network number is
+obtained from the peer. If the peer does not have the network number,
+the IPX protocol will not be started.
.TP
-.B ipx-node \fI<n>:<m>
+.B ipx-node \fIn\fB:\fIm
Set the IPX node numbers. The two node numbers are separated from each
-other with a colon character. The first number <n> is the local node
-number. The second number <m> is the peer's node number. Each node number
-is a hexadecimal number, to the maximum of ten significant digits. The
-node numbers on the ipx-network must be unique. There is no valid
-default. If this option is not specified then the node number is
-obtained from the peer. This option is a related to the
-\fIipxcp-accept-local\fR and \fIipxcp-accept-remote\fR options.
+other with a colon character. The first number \fIn\fR is the local
+node number. The second number \fIm\fR is the peer's node number. Each
+node number is a hexadecimal number, at most 10 digits long. The node
+numbers on the ipx-network must be unique. There is no valid
+default. If this option is not specified then the node numbers are
+obtained from the peer.
.TP
.B ipx-router-name \fI<string>
Set the name of the router. This is a string and is sent to the peer
as information data.
.TP
-.B ipx-routing \fI<n>
+.B ipx-routing \fIn
Set the routing protocol to be received by this option. More than one
instance of \fIipx-routing\fR may be specified. The '\fInone\fR'
option (0) may be specified as the only instance of ipx-routing. The
not specified, the peer will be forced to use the value which you have
specified.
.TP
-.B ipxcp-max-configure \fI<n>
+.B ipxcp-max-configure \fIn
Set the maximum number of IPXCP configure request frames which the
-system will send to <n>. The default is 10.
+system will send to \fIn\fR. The default is 10.
.TP
-.B ipxcp-max-failure \fI<n>
+.B ipxcp-max-failure \fIn
Set the maximum number of IPXCP NAK frames which the local system will
send before it rejects the options. The default value is 3.
.TP
-.B ipxcp-max-terminate \fI<n>
+.B ipxcp-max-terminate \fIn
Set the maximum nuber of IPXCP terminate request frames before the
local system considers that the peer is not listening to them. The
default value is 3.
\fIn\fR is a number which is the sum of the following values: 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.
+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 lcp-echo-failure \fI<n>
-If this option is given, \fIpppd\fR will presume the peer to be dead
+.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
-echo-reply. If this happens, \fIpppd\fR will terminate the
+echo-reply. If this happens, pppd will terminate the
connection. Use of this option requires a non-zero value for the
\fIlcp-echo-interval\fR parameter. This option can be used to enable
-\fIpppd\fR to terminate after the physical connection has been broken
+pppd to terminate after the physical connection has been broken
(e.g., the modem has hung up) in situations where no hardware modem
control lines are available.
.TP
-.B lcp-echo-interval \fI<n>
-If this option is given, \fIpppd\fR will send an LCP echo-request
-frame to the peer every \fIn\fR seconds. Under Linux, the
-echo-request is sent when no packets have been received from the peer
-for \fIn\fR seconds. Normally the peer should respond to the
-echo-request by sending an echo-reply. This option can be used with
-the \fIlcp-echo-failure\fR option to detect that the peer is no longer
-connected.
-.TP
-.B lcp-max-configure \fI<n>
-Set the maximum number of LCP configure-request transmissions to <n>
-(default 10).
+.B lcp-echo-interval \fIn
+If this option is given, pppd will send an LCP echo-request frame to
+the peer every \fIn\fR seconds. Normally the peer should respond to
+the echo-request by sending an echo-reply. This option can be used
+with the \fIlcp-echo-failure\fR option to detect that the peer is no
+longer connected.
.TP
-.B lcp-max-failure \fI<n>
+.B lcp-max-configure \fIn
+Set the maximum number of LCP configure-request transmissions to
+\fIn\fR (default 10).
+.TP
+.B lcp-max-failure \fIn
Set the maximum number of LCP configure-NAKs returned before starting
-to send configure-Rejects instead to <n> (default 10).
+to send configure-Rejects instead to \fIn\fR (default 10).
.TP
-.B lcp-max-terminate \fI<n>
-Set the maximum number of LCP terminate-request transmissions to <n>
-(default 3).
+.B lcp-max-terminate \fIn
+Set the maximum number of LCP terminate-request transmissions to
+\fIn\fR (default 3).
.TP
-.B lcp-restart \fI<n>
-Set the LCP restart interval (retransmission timeout) to <n> seconds
-(default 3).
+.B lcp-restart \fIn
+Set the LCP restart interval (retransmission timeout) to \fIn\fR
+seconds (default 3).
.TP
.B local
-Don't use the modem control lines. With this option,
-.B 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.
+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 login
Use the system password database for authenticating the peer using
-PAP, and record the user in the system wtmp file.
+PAP, and record the user in the system wtmp file. Note that the peer
+must have an entry in the /etc/ppp/pap-secrets file as well as the
+system password database to be allowed access.
+.TP
+.B maxconnect \fIn
+Terminate the connection when it has been available for network
+traffic for \fIn\fR seconds (i.e. \fIn\fR seconds after the first
+network control protocol comes up).
.TP
.B modem
Use the modem control lines. This option is the default. With this
-option,
-.B pppd
-will wait for the CD (Carrier Detect) signal from the modem to be asserted
-when opening the serial device
-(unless a connect script is specified), and it will drop the DTR (Data
-Terminal Ready) signal briefly when the connection is terminated and before
-executing the connect script.
-On Ultrix, this option implies hardware
-flow control, as for the \fBcrtscts\fR option.
+option, pppd will wait for the CD (Carrier Detect) signal from the
+modem to be asserted when opening the serial device (unless a connect
+script is specified), and it will drop the DTR (Data Terminal Ready)
+signal briefly when the connection is terminated and before executing
+the connect script. On Ultrix, this option implies hardware flow
+control, as for the \fIcrtscts\fR option.
.TP
.B ms-dns \fI<addr>
-If
-.I pppd
-is acting as a server for Microsoft Windows clients, this option
-allows
-.I pppd
-to supply one or two DNS (Domain Name Server) addresses to the
-clients. The first instance of this option specifies the primary DNS
-address; the second instance (if given) specifies the secondary DNS
-address.
-.TP
-.B name \fI<n>
-Set the name of the local system for authentication purposes to <n>.
-.TP
-.B netmask \fI<n>
-Set the interface netmask to <n>, a 32 bit netmask in "decimal dot"
+If pppd is acting as a server for Microsoft Windows clients, this
+option allows pppd to supply one or two DNS (Domain Name Server)
+addresses to the clients. The first instance of this option specifies
+the primary DNS address; the second instance (if given) specifies the
+secondary DNS address. (This option was present in some older
+versions of pppd under the name \fBdns-addr\fR.)
+.TP
+.B ms-wins \fI<addr>
+If pppd is acting as a server for Microsoft Windows or "Samba"
+clients, this option allows pppd to supply one or two WINS (Windows
+Internet Name Services) server addresses to the clients. The first
+instance of this option specifies the primary WINS address; the second
+instance (if given) specifies the secondary WINS address.
+.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
+use lines in the secrets files which have \fIname\fR as the second
+field when looking for a secret to use in authenticating the peer. In
+addition, unless overridden with the \fIuser\fR option, \fIname\fR
+will be used as the name to send to the peer when authenticating the
+local system to the peer. (Note that pppd does not append the domain
+name to \fIname\fR.)
+.TP
+.B netmask \fIn
+Set the interface netmask to \fIn\fR, a 32 bit netmask in "decimal dot"
notation (e.g. 255.255.255.0). If this option is given, the value
specified is ORed with the default netmask. The default netmask is
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
receive).
.TP
+.B noauth
+Do not require the peer to authenticate itself. This option is
+privileged.
+.TP
.B nobsdcomp
Disables BSD-Compress compression; \fBpppd\fR will not request or
agree to compress packets using the BSD-Compress scheme.
.B noccp
Disable CCP (Compression Control Protocol) negotiation. This option
should only be required if the peer is buggy and gets confused by
-requests from
-.I pppd
-for CCP negotiation.
+requests from pppd for CCP negotiation.
.TP
.B nocrtscts
-Disable hardware flow control (i.e. RTS/CTS) on the serial port. If
-neither the \fBcrtscts\fR nor the \fB\-crtscts\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 \fInodtrcts\fR option is given, the hardware
+flow control setting for the serial port is left unchanged.
+.TP
+.B nodtrcts
+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 \fBdefaultroute\fR option. The system administrator who
-wishes to prevent users from creating default routes with \fIpppd\fR
+Disable the \fIdefaultroute\fR option. The system administrator who
+wishes to prevent users from creating default routes with pppd
can do so by placing this option in the /etc/ppp/options file.
.TP
.B nodeflate
-Disables Deflate compression; \fBpppd\fR will not request or agree to
+Disables Deflate compression; pppd will not request or agree to
compress packets using the Deflate scheme.
.TP
.B nodetach
-Don't detach from the controlling terminal. Without this option,
-if a serial device other than its controlling terminal is specified,
-.I pppd
-will fork to become a background process.
+Don't detach from the controlling terminal. Without this option, if a
+serial device other than the terminal on the standard input is
+specified, pppd will fork to become a background process.
.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
-.I pppd
-for IPCP negotiation.
+from pppd for IPCP negotiation.
.TP
.B noipdefault
Disables the default behaviour when no local IP address is specified,
.TP
.B noipx
Disable the IPXCP and IPX protocols. This option should only be
-required if the peer is buggy and gets confused by requests from
-.I pppd
+required if the peer is buggy and gets confused by requests from pppd
for IPXCP negotiation.
.TP
.B nomagic
-Disable magic number negotiation. With this option,
-.I pppd
-cannot detect a looped-back line. This option should only be needed
-if the peer is buggy.
+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 nopcomp
Disable protocol field compression negotiation in both the receive and
the transmit direction.
.TP
+.B nopersist
+Exit once a connection has been made and terminated. This is the
+default unless the \fIpersist\fR or \fIdemand\fR option has been
+specified.
+.TP
.B nopredictor1
Do not accept or agree to Predictor-1 comprssion.
.TP
.B noproxyarp
-Disable the \fBproxyarp\fR option. The system administrator who
-wishes to prevent users from creating proxy ARP entries with
-\fIpppd\fR can do so by placing this option in the /etc/ppp/options
-file.
+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
.TP
.B novjccomp
Disable the connection-ID compression option in Van Jacobson style
-TCP/IP header compression. With this option, \fIpppd\fR will not omit
-the connection-ID byte from Van Jacobson compressed TCP/IP headers,
-nor ask the peer to do so.
+TCP/IP header compression. With this option, pppd will not omit the
+connection-ID byte from Van Jacobson compressed TCP/IP headers, nor
+ask the peer to do so.
.TP
.B papcrypt
-Indicates that all secrets in the /etc/ppp/pap-secrets file which
-are used for checking the identity of the peer are encrypted, and thus
-pppd should not accept a password which (before encryption) is
+Indicates that all secrets in the /etc/ppp/pap-secrets file which are
+used for checking the identity of the peer are encrypted, and thus
+pppd should not accept a password which, before encryption, is
identical to the secret from the /etc/ppp/pap-secrets file.
.TP
-.B pap-max-authreq \fI<n>
+.B pap-max-authreq \fIn
Set the maximum number of PAP authenticate-request transmissions to
-<n> (default 10).
+\fIn\fR (default 10).
.TP
-.B pap-restart \fI<n>
-Set the PAP restart interval (retransmission timeout) to <n> seconds
-(default 3).
+.B pap-restart \fIn
+Set the PAP restart interval (retransmission timeout) to \fIn\fR
+seconds (default 3).
.TP
-.B pap-timeout \fI<n>
-Set the maximum time that
-.I pppd
-will wait for the peer to authenticate itself with PAP to
-<n> seconds (0 means no limit).
+.B pap-timeout \fIn
+Set the maximum time that pppd will wait for the peer to authenticate
+itself with PAP to \fIn\fR seconds (0 means no limit).
.TP
.B pass-filter \fIfilter-expression
Specifies a packet filter to applied to data packets being sent or
received to determine which packets should be allowed to pass.
Packets which are rejected by the filter are silently discarded. This
-option can be used to provide protection against IP address spoofing
-and other attacks.
+option can be used to prevent specific network daemons (such as
+routed) using up link bandwidth, or to provide a basic firewall
+capability.
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. Note that it
is possible to apply different constraints to incoming and outgoing
-packets using the \fBinbound\fR and \fBoutbound\fR qualifiers.
+packets using the \fBinbound\fR and \fBoutbound\fR qualifiers. 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 persist
Do not exit after a connection is terminated; instead try to reopen
the connection.
.TP
.B predictor1
-Attempt to request that the peer send frames which
-have been compressed using Predictor-1 compression. This option will
-be ignored unless Predictor-1 code has been loaded into the kernel.
+Request that the peer compress frames that it sends using Predictor-1
+compression, and agree to compress transmitted frames with 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.
-.TP
-.B remotename \fI<n>
+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.
+.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 <n>.
+to \fIname\fR.
.TP
.B refuse-chap
-With this option, \fIpppd\fR will not agree to authenticate itself
-to the peer using CHAP.
+With this option, pppd will not agree to authenticate itself to the
+peer using CHAP.
.TP
.B refuse-pap
-With this option, \fIpppd\fR will not agree to authenticate itself
-to the peer using PAP.
+With this option, pppd will not agree to authenticate itself to the
+peer using PAP.
.TP
.B require-chap
-Require the peer to authenticate itself using CHAP [Cryptographic
+Require the peer to authenticate itself using CHAP [Challenge
Handshake Authentication Protocol] authentication.
.TP
.B require-pap
Authentication Protocol] authentication.
.TP
.B silent
-With this option,
-.I 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 \fIpppd\fR).
+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 support synchronous
+serial communications. Currently supports Microgate SyncLink adapters
+under Linux.
.TP
.B usehostname
-Enforce the use of the hostname as the name of the local system for
-authentication purposes (overrides the
-.B name
-option).
+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). This option is not normally needed since the
+\fIname\fR option is privileged.
.TP
-.B user \fI<u>
-Set the user name to use for authenticating this machine with the peer
-using PAP to <u>.
+.B user \fIname
+Sets the name used for authenticating the local system to the peer to
+\fIname\fR.
.TP
.B vj-max-slots \fIn
Sets the number of connection slots to be used by the Van Jacobson
TCP/IP header compression and decompression code to \fIn\fR, which
must be between 2 and 16 (inclusive).
.TP
+.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. 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
-the serial port. This option is only implemented on Linux systems
-at present.
+the serial port.
.SH OPTIONS FILES
-Options can be taken from files as well as the command line.
-.I pppd
-reads options from the files /etc/ppp/options and ~/.ppprc before
-looking at the command line. 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. A hash (#) starts a comment, which continues
-until the end of the line.
-.SH AUTHENTICATION
+Options can be taken from files as well as the command line. Pppd
+reads options from the files /etc/ppp/options, ~/.ppprc and
+/etc/ppp/options.\fIttyname\fR (in that order) before processing the
+options on the command line. (In fact, the command-line options are
+scanned to find the terminal name before the options.\fIttyname\fR
+file is read.) In forming the name of the options.\fIttyname\fR file,
+the initial /dev/ is removed from the terminal name, and any remaining
+/ characters are replaced with dots.
+.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 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.
+.SH SECURITY
.I pppd
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 require authentication whenever
-.I pppd
-is run, 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 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
+user running a setuid-root pppd, either on the command line, in the
+user's ~/.ppprc file, or in an options file read using the \fIfile\fR
+option. Privileged options may be used in /etc/ppp/options file or in
+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
+other, together with some kind of secret information which could only
+come from the genuine authorized user of that name. In such an
+exchange, we will call the first peer the "client" and the other the
+"server". The client has a name by which it identifies itself to the
+server, and the server also has a name by which it identifies itself
+to the client. Generally the genuine client shares some secret (or
+password) with the server, and authenticates itself by proving that it
+knows that secret. Very often, the names used for authentication
+correspond to the internet hostnames of the peers, but this is not
+essential.
.LP
-The default behaviour of
-.I pppd
-is to agree to authenticate if requested, and to not
-require authentication from the peer. However,
-.I pppd
-will not agree to
-authenticate itself with a particular protocol if it has no secrets
-which could be used to do so.
+At present, pppd supports two authentication protocols: the Password
+Authentication Protocol (PAP) and the Challenge Handshake
+Authentication Protocol (CHAP). PAP involves the client sending its
+name and a cleartext password to the server to authenticate itself.
+In contrast, the server initiates the CHAP authentication exchange by
+sending a challenge to the client (the challenge packet includes the
+server's name). The client must respond with a response which
+includes its name plus a hash value derived from the shared secret and
+the challenge, in order to prove that it knows the secret.
.LP
-Authentication is based on secrets, which are selected from secrets
-files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP).
-Both secrets files have the same format, and both can store secrets
-for several combinations of server (authenticating peer) and client
-(peer being authenticated). Note that
-.I pppd
-can be both a server
-and client, and that different protocols can be used in the two
-directions if desired.
+The PPP protocol, being symmetrical, allows both peers to require the
+other to authenticate itself. In that case, two separate and
+independent authentication exchanges will occur. The two exchanges
+could use different authentication protocols, and in principle,
+different names could be used in the two exchanges.
.LP
-A secrets file is parsed into words as for a options file. A secret
-is specified by a line containing at least 3 words, in the order
-client name, server name, secret. 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, it is assumed that any IP address
-is OK; to disallow all IP addresses, use "-". If the secret starts
-with an `@', what follows is assumed to be the name of a file from
-which to read the secret. A "*" as the client or server name matches
-any name. When selecting a secret, \fIpppd\fR takes the best match, i.e.
-the match with the fewest wildcards.
+The default behaviour of pppd is to agree to authenticate if
+requested, and to not require authentication from the peer. However,
+pppd will not agree to authenticate itself with a particular protocol
+if it has no secrets which could be used to do so.
.LP
-Thus a secrets file contains both secrets for use in authenticating
-other hosts, plus secrets which we use for authenticating ourselves to
-others. Which secret to use is chosen based on the names of the host
-(the `local name') and its peer (the `remote name'). The local name
-is set as follows:
-.TP 3
-if the \fBusehostname\fR option is given,
-then the local name is the hostname of this machine
-(with the domain appended, if given)
-.TP 3
-else if the \fBname\fR option is given,
-then use the argument of the first \fBname\fR option seen
-.TP 3
-else if the local IP address is specified with a hostname,
-then use that name
-.TP 3
-else use the hostname of this machine (with the domain appended, if given)
+Pppd stores secrets for use in authentication in secrets
+files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for 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
+systems to itself.
+.LP
+Each line in a secrets file contains one secret. A given secret is
+specific to a particular combination of client and server - it can
+only be used by that client to authenticate itself to that server.
+Thus each line in a secrets file has at least 3 fields: the name of
+the client, the name of the server, and the secret. These fields may
+be followed by a list of the IP addresses that the specified client
+may use when connecting to the specified server.
.LP
-When authenticating ourselves using PAP, there is also a `username'
-which is the local name by default, but can be set with the \fBuser\fR
-option or the \fB+ua\fR option.
+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
+and in the secret.
.LP
-The remote name is set as follows:
-.TP 3
-if the \fBremotename\fR option is given,
-then use the argument of the last \fBremotename\fR option seen
-.TP 3
-else if the remote IP address is specified with a hostname,
-then use that host name
-.TP 3
-else the remote name is the null string "".
+If the secret starts with an `@', what follows is assumed to be the
+name of a file from which to read the secret. A "*" as the client or
+server name matches any name. When selecting a secret, pppd takes the
+best match, i.e. the match with the fewest wildcards.
.LP
-Secrets are selected from the PAP secrets file as follows:
-.TP 2
-*
-For authenticating the peer, look for a secret with client ==
-username specified in the PAP authenticate-request, and server ==
-local name.
-.TP 2
-*
-For authenticating ourselves to the peer, look for a secret with
-client == our username, server == remote name.
+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
+identity), it chooses a secret with the peer's name in the first
+field and the name of the local system in the second field. The
+name of the local system defaults to the hostname, with the domain
+name appended if the \fIdomain\fR option is used. This default can be
+overridden with the \fIname\fR option, except when the
+\fIusehostname\fR option is used.
.LP
-When authenticating the peer with PAP, a secret of "" matches any
-password supplied by the peer. If the password doesn't match the
-secret, the password is encrypted using crypt() and checked against
-the secret again; thus secrets for authenticating the peer can be
-stored in encrypted form. If the \fBpapcrypt\fR option is given, the
-first (unencrypted) comparison is omitted, for better security.
+When pppd is choosing a secret to use in authenticating itself to the
+peer, it first determines what name it is going to use to identify
+itself to the peer. This name can be specified by the user with the
+\fIuser\fR option. If this option is not used, the name defaults to
+the name of the local system, determined as described in the previous
+paragraph. Then pppd looks for a secret with this name in the first
+field and the peer's name in the second field. Pppd will know the
+name of the peer if CHAP authentication is being used, because the
+peer will have sent it in the challenge packet. However, if PAP is being
+used, pppd will have to determine the peer's name from the options
+specified by the user. The user can specify the peer's name directly
+with the \fIremotename\fR option. Otherwise, if the remote IP address
+was specified by a name (rather than in numeric form), that name will
+be used as the peer's name. Failing that, pppd will use the null
+string as the peer's name.
.LP
-If the \fBlogin\fR option was specified, the
-username and password are also checked against the system password
-database. Thus, the system administrator can set up the pap-secrets
-file to allow PPP access only to certain users, and to restrict the
-set of IP addresses that each user can use. Typically, when using the
-\fBlogin\fR option, the secret in /etc/ppp/pap-secrets would be "", to
-avoid the need to have the same secret in two places.
+When authenticating the peer with PAP, the supplied password is first
+compared with the secret from the secrets file. If the password
+doesn't match the secret, the password is encrypted using crypt() and
+checked against the secret again. Thus secrets for authenticating the
+peer can be stored in encrypted form if desired. If the
+\fIpapcrypt\fR option is given, the first (unencrypted) comparison is
+omitted, for better security.
.LP
-Secrets are selected from the CHAP secrets file as follows:
-.TP 2
-*
-For authenticating the peer, look for a secret with client == name
-specified in the CHAP-Response message, and server == local name.
-.TP 2
-*
-For authenticating ourselves to the peer, look for a secret with
-client == local name, and server == name specified in the
-CHAP-Challenge message.
+Furthermore, if the \fIlogin\fR option was specified, the username and
+password are also checked against the system password database. Thus,
+the system administrator can set up the pap-secrets file to allow PPP
+access only to certain users, and to restrict the set of IP addresses
+that each user can use. Typically, when using the \fIlogin\fR option,
+the secret in /etc/ppp/pap-secrets would be "", which will match any
+password supplied by the peer. This avoids the need to have the same
+secret in two places.
.LP
Authentication must be satisfactorily completed before IPCP (or any
-other Network Control Protocol) can be started. If authentication
-fails, \fIpppd\fR will terminated the link (by closing LCP). If IPCP
-negotiates an unacceptable IP address for the remote host, IPCP will
-be closed. IP packets can only be sent or received when IPCP is open.
+other Network Control Protocol) can be started. If the peer is
+required to authenticate itself, and fails to do so, pppd will
+terminated the link (by closing LCP). If IPCP negotiates an
+unacceptable IP address for the remote host, IPCP will be closed. IP
+packets can only be sent or received when IPCP is open.
.LP
In some cases it is desirable to allow some hosts which can't
authenticate themselves to connect and use one of a restricted set of
IP addresses, even when the local host generally requires
authentication. If the peer refuses to authenticate itself when
-requested, \fIpppd\fR takes that as equivalent to authenticating with
-PAP using the empty string for the username and password. Thus, by
-adding a line to the pap-secrets file which specifies the empty string
-for the client and password, it is possible to allow restricted access
-to hosts which refuse to authenticate themselves.
+requested, pppd takes that as equivalent to authenticating with PAP
+using the empty string for the username and password. Thus, by adding
+a line to the pap-secrets file which specifies the empty string for
+the client and password, it is possible to allow restricted access to
+hosts which refuse to authenticate themselves.
.SH ROUTING
.LP
-When IPCP negotiation is completed successfully,
-.I pppd
-will inform the kernel of the local and remote IP addresses for the
-ppp interface. This is sufficient to create a
-host route to the remote end of the link, which will enable the peers
-to exchange IP packets. Communication with other machines generally
-requires further modification to routing tables and/or ARP (Address
-Resolution Protocol) tables. In some cases this will be done
-automatically through the actions of the \fIrouted\fR or \fIgated\fR
-daemons, but in most cases some further intervention is required.
+When IPCP negotiation is completed successfully, pppd will inform the
+kernel of the local and remote IP addresses for the ppp interface.
+This is sufficient to create a host route to the remote end of the
+link, which will enable the peers to exchange IP packets.
+Communication with other machines generally requires further
+modification to routing tables and/or ARP (Address Resolution
+Protocol) tables. In most cases the \fIdefaultroute\fR and/or
+\fIproxyarp\fR options are sufficient for this, but in some cases
+further intervention is required. The /etc/ppp/ip-up script can be
+used for this.
.LP
-Sometimes it is desirable
-to add a default route through the remote host, as in the case of a
-machine whose only connection to the Internet is through the ppp
-interface. The \fBdefaultroute\fR option causes \fIpppd\fR to create such a
-default route when IPCP comes up, and delete it when the link is
-terminated.
+Sometimes it is desirable to add a default route through the remote
+host, as in the case of a machine whose only connection to the
+Internet is through the ppp interface. The \fIdefaultroute\fR option
+causes pppd to create such a default route when IPCP comes up, and
+delete it when the link is terminated.
.LP
In some cases it is desirable to use proxy ARP, for example on a
server machine connected to a LAN, in order to allow other hosts to
-communicate with the remote host. The \fBproxyarp\fR option causes \fIpppd\fR
-to look for a network interface on the same subnet as the remote host
-(an interface supporting broadcast and ARP, which is up and not a
-point-to-point or loopback interface). If found, \fIpppd\fR creates a
+communicate with the remote host. The \fIproxyarp\fR option causes
+pppd to look for a network interface on the same subnet as the remote
+host (an interface supporting broadcast and ARP, which is up and not a
+point-to-point or loopback interface). If found, pppd creates a
permanent, published ARP entry with the IP address of the remote host
and the hardware address of the network interface found.
+.LP
+When the \fIdemand\fR option is used, the interface IP addresses have
+already been set at the point when IPCP comes up. If pppd has not
+been able to negotiate the same addresses that it used to configure
+the interface (for example when the peer is an ISP that uses dynamic
+IP address assignment), pppd has to change the interface IP addresses
+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 EXAMPLES
.LP
-In the simplest case, you can connect the serial ports of two machines
-and issue a command like
+The following examples assume that the /etc/ppp/options file contains
+the \fIauth\fR option (as in the default /etc/ppp/options file in the
+ppp distribution).
+.LP
+Probably the most common use of pppd is to dial out to an ISP. This
+can be done with a command such as
+.IP
+pppd call isp
+.LP
+where the /etc/ppp/peers/isp file is set up by the system
+administrator to contain something like this:
.IP
-pppd /dev/ttya 9600 passive
+ttyS0 19200 crtscts
+.br
+connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
+.br
+noauth
.LP
-to each machine, assuming there is no \fIgetty\fR running on the
-serial ports. If one machine has a \fIgetty\fR running, you can use
-\fIkermit\fR or \fItip\fR on the other machine to log in to the first
-machine and issue a command like
+In this example, we are using chat to dial the ISP's modem and go
+through any logon sequence required. The /etc/ppp/chat-isp file
+contains the script used by chat; it could for example contain
+something like this:
.IP
-pppd passive
+ABORT "NO CARRIER"
+.br
+ABORT "NO DIALTONE"
+.br
+ABORT "ERROR"
+.br
+ABORT "NO ANSWER"
+.br
+ABORT "BUSY"
+.br
+ABORT "Username/Password Incorrect"
+.br
+"" "at"
+.br
+OK "at&d0&c1"
+.br
+OK "atdt2468135"
+.br
+"name:" "^Umyuserid"
+.br
+"word:" "\\qmypassword"
+.br
+"ispts" "\\q^Uppp"
+.br
+"~-^Uppp-~"
+.LP
+See the chat(8) man page for details of chat scripts.
.LP
-Then exit from the communications program (making sure the connection
-isn't dropped), and issue a command like
+Pppd can also be used to provide a dial-in ppp service for users. If
+the users already have login accounts, the simplest way to set up the
+ppp service is to let the users log in to their accounts and run pppd
+(installed setuid-root) with a command such as
.IP
-pppd /dev/ttya 9600
+pppd proxyarp
.LP
-The process of logging in to the other machine and starting \fIpppd\fR
-can be automated by using the \fBconnect\fR option to run \fIchat\fR,
-for example:
+To allow a user to use the PPP facilities, you need to allocate an IP
+address for that user's machine and create an entry in
+/etc/ppp/pap-secrets or /etc/ppp/chap-secrets (depending on which
+authentication method the PPP implementation on the user's machine
+supports), so that the user's
+machine can authenticate itself. For example, if Joe has a machine
+called "joespc" which is to be allowed to dial in to the machine
+called "server" and use the IP address joespc.my.net, you would add an
+entry like this to /etc/ppp/pap-secrets or /etc/ppp/chap-secrets:
.IP
-pppd /dev/ttya 38400 connect 'chat "" "" "login:" "username"
-"Password:" "password" "% " "exec pppd passive"'
+joespc server "joe's secret" joespc.my.net
.LP
-(Note however that running chat like this will leave the password
-visible in the parameter list of pppd and chat.)
+Alternatively, you can create a username called (for example) "ppp",
+whose login shell is pppd and whose home directory is /etc/ppp.
+Options to be used when pppd is run this way can be put in
+/etc/ppp/.ppprc.
.LP
If your serial connection is any more complicated than a piece of
wire, you may need to arrange for some control characters to be
escaped. In particular, it is often useful to escape XON (^Q) and
-XOFF (^S), using \fBasyncmap a0000\fR. If the path includes a telnet,
-you probably should escape ^] as well (\fBasyncmap 200a0000\fR).
-If the path includes an rlogin, you will need to use the \fBescape
-ff\fR option on the end which is running the rlogin client, since many
-rlogin implementations are not
-transparent; they will remove the sequence [0xff, 0xff, 0x73, 0x73,
-followed by any 8 bytes] from the stream.
+XOFF (^S), using \fIasyncmap a0000\fR. If the path includes a telnet,
+you probably should escape ^] as well (\fIasyncmap 200a0000\fR). If
+the path includes an rlogin, you will need to use the \fIescape ff\fR
+option on the end which is running the rlogin client, since many
+rlogin implementations are not transparent; they will remove the
+sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the
+stream.
.SH DIAGNOSTICS
.LP
Messages are sent to the syslog daemon using facility LOG_DAEMON.
-(This can be overriden by recompiling \fIpppd\fR with the macro
+(This can be overriden by recompiling pppd with the macro
LOG_PPP defined as the desired facility.) In order to see the error
and debug messages, you will need to edit your /etc/syslog.conf file
to direct the messages to the desired output device or file.
.LP
-The \fBdebug\fR option causes the contents of all control packets sent
+The \fIdebug\fR option causes the contents of all control packets sent
or received to be logged, that is, all LCP, PAP, CHAP or IPCP packets.
-This can be useful if the PPP negotiation does not succeed.
-If debugging is enabled at compile time, the \fBdebug\fR option also
+This can be useful if the PPP negotiation does not succeed or if
+authentication fails.
+If debugging is enabled at compile time, the \fIdebug\fR option also
causes other debugging messages to be logged.
.LP
-Debugging can also be enabled or disabled by sending a
-SIGUSR1 to the
-.I pppd
-process. This signal acts as a toggle.
-.SH FILES
+Debugging can also be enabled or disabled by sending a SIGUSR1 signal
+to the pppd process. This signal acts as a toggle.
+.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.
+.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
+successfully authenticates itself. It is executed with the parameters
+.IP
+\fIinterface-name peer-name user-name tty-device speed\fR
+.IP
+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 /var/run/ppp\fIn\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp\fIn\fB.pid \fR(others)
-Process-ID for \fIpppd\fR process on ppp interface unit \fIn\fR.
+.B /etc/ppp/auth-down
+A program or script which is executed when the link goes down, if
+/etc/ppp/auth-up was previously executed. It is executed in the same
+manner with the same parameters as /etc/ppp/auth-up.
.TP
.B /etc/ppp/ip-up
A program or script which is executed when the link is available for
executed with the parameters
.IP
\fIinterface-name tty-device speed local-IP-address
-remote-IP-address\fR
-.IP
-and with its standard input,
-output and error streams redirected to \fB/dev/null\fR.
-.IP
-This program or script is executed with the same real and effective
-user-ID as \fIpppd\fR, that is, at least the effective user-ID and
-possibly the real user-ID will be \fBroot\fR. This is so that it can
-be used to manipulate routes, run privileged daemons (e.g.
-\fBsendmail\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 without an environment, so you
-must either specify a PATH or use full pathnames (e.g. \fI/sbin/route\fR,
-as opposed to \fIroute\fR).
+remote-IP-address ipparam\fR
.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 with the same parameters as the ip-up script, and the same
-security considerations apply, since it is executed with the same
-effective and real user-IDs as \fIpppd\fR.
+invoked in the same manner and with the same parameters as the ip-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 \fB/dev/null\fR.
-.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 same real and effective
-user-ID as \fIpppd\fR, that is, at least the effective user-ID and
-possibly the real user-ID will be \fBroot\fR. This is so that it can
-be used to manipulate routes, run privileged daemons (e.g.
-\fBripd\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 with the same parameters as the ipx-up script, and the same
-security considerations apply, since it is executed with the same
-effective and real user-IDs as \fIpppd\fR.
+invoked in the same manner and with the same parameters as the ipx-up
+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 /etc/ppp/pap-secrets
-Usernames, passwords and IP addresses for PAP authentication.
+Usernames, passwords and IP addresses for PAP authentication. 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.
.TP
.B /etc/ppp/chap-secrets
-Names, secrets and IP addresses for CHAP authentication.
+Names, secrets and IP addresses for 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.
.TP
.B /etc/ppp/options
-System default options for
-.I pppd,
-read before user default options or command-line options.
+System default options for pppd, read before user default options or
+command-line options.
.TP
.B ~/.ppprc
-User default options, read before command-line options.
+User default options, read before /etc/ppp/options.\fIttyname\fR.
.TP
.B /etc/ppp/options.\fIttyname
System default options for the serial port being used, read after
-command-line options. In forming the \fIttyname\fR part of this
+~/.ppprc. In forming the \fIttyname\fR part of this
filename, an initial /dev/ is stripped from the port name (if
present), and any slashes in the remaining part are converted to
dots.
+.TP
+.B /etc/ppp/peers
+A directory containing options files which may contain privileged
+options, even if pppd was invoked by a user other than root. The
+system administrator can create options files in this directory to
+permit non-privileged users to dial out without requiring the peer to
+authenticate, but only to certain trusted peers.
.SH SEE ALSO
.TP
.B RFC1144
Jacobson, V.
-.I Compressing TCP/IP headers for low-speed serial links.
+\fICompressing TCP/IP headers for low-speed serial links.\fR
February 1990.
.TP
.B RFC1321
.I PPP in HDLC-like Framing.
July 1994.
.SH NOTES
-The following signals have the specified effect when sent to the
-.I pppd
-process.
+The following signals have the specified effect when sent to pppd.
.TP
.B SIGINT, SIGTERM
-These signals cause \fBpppd\fR to terminate the link (by closing LCP),
+These signals cause pppd to terminate the link (by closing LCP),
restore the serial device settings, and exit.
.TP
.B SIGHUP
-This signal causes \fBpppd\fR to terminate the link, restore the
-serial device settings, and close the serial device. If the
-\fBpersist\fR option has been specified, \fBpppd\fR will try to reopen
-the serial device and start another connection. Otherwise \fBpppd\fR
-will exit.
+This signal causes pppd to terminate the link, restore the serial
+device settings, and close the serial device. If the \fIpersist\fR or
+\fIdemand\fR option has been specified, pppd will try to reopen the
+serial device and start another connection (after the holdoff period).
+Otherwise pppd will exit. If this signal is received during the
+holdoff period, it causes pppd to end the holdoff period immediately.
+.TP
+.B SIGUSR1
+This signal toggles the state of the \fIdebug\fR option.
.TP
.B SIGUSR2
-This signal causes
-.B pppd
-to renegotiate compression. This can be useful to re-enable
-compression after it has been disabled as a result of a fatal
-decompression error. With the BSD Compress scheme, fatal
-decompression errors generally indicate a bug in one or other
-implementation.
+This signal causes pppd to renegotiate compression. This can be
+useful to re-enable compression after it has been disabled as a result
+of a fatal decompression error. (Fatal decompression errors generally
+indicate a bug in one or other implementation.)
.SH AUTHORS
-Paul Mackerras (paulus@cs.anu.edu.au), based on earlier work by
+Paul Mackerras (Paul.Mackerras@cs.anu.edu.au), based on earlier work by
Drew Perkins,
Brad Clements,
Karl Fox,
projects / ppp.git / blobdiff