1 .\" manual page [] for pppd 2.4
2 .\" $Id: pppd.8,v 1.63 2002/05/21 17:26:49 dfs Exp $
4 .\" SS subsection heading
6 .\" IP indented paragraph
10 pppd \- Point to Point Protocol daemon
22 The Point-to-Point Protocol (PPP) provides a method for transmitting
23 datagrams over serial point-to-point links. PPP
24 is composed of three parts: a method for encapsulating datagrams over
25 serial links, an extensible Link Control Protocol (LCP), and
26 a family of Network Control Protocols (NCP) for establishing
27 and configuring different network-layer protocols.
29 The encapsulation scheme is provided by driver code in the kernel.
30 Pppd provides the basic LCP, authentication support, and an NCP for
31 establishing and configuring the Internet Protocol (IP) (called the IP
32 Control Protocol, IPCP).
33 .SH FREQUENTLY USED OPTIONS
36 Communicate over the named device. The string "/dev/" is prepended if
37 necessary. If no device name is given, or if the name of the terminal
38 connected to the standard input is given, pppd will use that terminal,
39 and will not fork to put itself in the background. A value for this
40 option from a privileged source cannot be overridden by a
44 Set the baud rate to <speed> (a decimal number). On systems such as
45 4.4BSD and NetBSD, any speed can be specified. Other systems
46 (e.g. SunOS) allow only a limited set of speeds.
49 Set the async character map to <map>. This map describes which
50 control characters cannot be successfully received over the serial
51 line. Pppd will ask the peer to send these characters as a 2-byte
52 escape sequence. The argument is a 32 bit hex number with each bit
53 representing a character to escape. Bit 0 (00000001) represents the
54 character 0x00; bit 31 (80000000) represents the character 0x1f or ^_.
55 If multiple \fIasyncmap\fR options are given, the values are ORed
56 together. If no \fIasyncmap\fR option is given, no async character
57 map will be negotiated for the receive direction; the peer should then
58 escape \fIall\fR control characters. To escape transmitted
59 characters, use the \fIescape\fR option.
62 Require the peer to authenticate itself before allowing network
63 packets to be sent or received. This option is the default if the
64 system has a default route. If neither this option nor the
65 \fInoauth\fR option is specified, pppd will only allow the peer to use
66 IP addresses to which the system does not already have a route.
69 Read options from the file /etc/ppp/peers/\fIname\fR. This file may
70 contain privileged options, such as \fInoauth\fR, even if pppd
71 is not being run by root. The \fIname\fR string may not begin with /
72 or include .. as a pathname component. The format of the options file
76 Use the executable or shell command specified by \fIscript\fR to set
77 up the serial line. This script would typically use the chat(8)
78 program to dial the modem and start the remote ppp session. A value
79 for this option from a privileged source cannot be overridden by a
83 Use hardware flow control (i.e. RTS/CTS) to control the flow of
84 data on the serial port. If neither the \fIcrtscts\fR, the
85 \fInocrtscts\fR, the \fIcdtrcts\fR nor the \fInocdtrcts\fR option
86 is given, the hardware flow control setting for the serial port is
88 Some serial ports (such as Macintosh serial ports) lack a true
89 RTS output. Such serial ports use this mode to implement
90 unidirectional flow control. The serial port will
91 suspend transmission when requested by the modem (via CTS)
92 but will be unable to request the modem stop sending to the
93 computer. This mode retains the ability to use DTR as
97 Add a default route to the system routing tables, using the peer as
98 the gateway, when IPCP negotiation is successfully completed.
99 This entry is removed when the PPP connection is broken. This option
100 is privileged if the \fInodefaultroute\fR option has been specified.
102 .B disconnect \fIscript
103 Run the executable or shell command specified by \fIscript\fR after
104 pppd has terminated the link. This script could, for example, issue
105 commands to the modem to cause it to hang up if hardware modem control
106 signals were not available. The disconnect script is not run if the
107 modem has already hung up. A value for this option from a privileged
108 source cannot be overridden by a non-privileged user.
110 .B escape \fIxx,yy,...
111 Specifies that certain characters should be escaped on transmission
112 (regardless of whether the peer requests them to be escaped with its
113 async control character map). The characters to be escaped are
114 specified as a list of hex numbers separated by commas. Note that
115 almost any character can be specified for the \fIescape\fR option,
116 unlike the \fIasyncmap\fR option which only allows control characters
117 to be specified. The characters which may not be escaped are those
118 with hex values 0x20 - 0x3f or 0x5e.
121 Read options from file \fIname\fR (the format is described below).
122 The file must be readable by the user who has invoked pppd.
125 Run the executable or shell command specified by \fIscript\fR to
126 initialize the serial line. This script would typically use the
127 chat(8) program to configure the modem to enable auto answer. A value
128 for this option from a privileged source cannot be overridden by a
132 Specifies that pppd should create a UUCP-style lock file for the
133 serial device to ensure exclusive access to the device.
136 Set the MRU [Maximum Receive Unit] value to \fIn\fR. Pppd
137 will ask the peer to send packets of no more than \fIn\fR bytes. The
138 minimum MRU value is 128. The default MRU value is 1500. A value of
139 296 is recommended for slow links (40 bytes for TCP/IP header + 256
140 bytes of data). (Note that for IPv6 MRU must be at least 1280)
143 Set the MTU [Maximum Transmit Unit] value to \fIn\fR. Unless the
144 peer requests a smaller value via MRU negotiation, pppd will
145 request that the kernel networking code send data packets of no more
146 than \fIn\fR bytes through the PPP network interface. (Note that for
147 IPv6 MTU must be at least 1280)
150 Enables the "passive" option in the LCP. With this option, pppd will
151 attempt to initiate a connection; if no reply is received from the
152 peer, pppd will then just wait passively for a valid LCP packet from
153 the peer, instead of exiting, as it would without this option.
156 .I <local_IP_address>\fB:\fI<remote_IP_address>
157 Set the local and/or remote interface IP addresses. Either one may be
158 omitted. The IP addresses can be specified with a host name or in
159 decimal dot notation (e.g. 150.234.56.78). The default local
160 address is the (first) IP address of the system (unless the
162 option is given). The remote address will be obtained from the peer
163 if not specified in any option. Thus, in simple cases, this option is
164 not required. If a local and/or remote IP address is specified with
166 will not accept a different value from the peer in the IPCP
167 negotiation, unless the \fIipcp-accept-local\fR and/or
168 \fIipcp-accept-remote\fR options are given, respectively.
170 .B ipv6 \fI<local_interface_identifier>\fR,\fI<remote_interface_identifier>
171 Set the local and/or remote 64-bit interface identifier. Either one may be
172 omitted. The identifier must be specified in standard ascii notation of
173 IPv6 addresses (e.g. ::dead:beef). If the
174 \fIipv6cp-use-ipaddr\fR
175 option is given, the local identifier is the local IPv4 address (see above).
176 On systems which supports a unique persistent id, such as EUI-48 derived
177 from the Ethernet MAC address, \fIipv6cp-use-persistent\fR option can be
178 used to replace the \fIipv6 <local>,<remote>\fR option. Otherwise the
179 identifier is randomized.
181 .B active-filter \fIfilter-expression
182 Specifies a packet filter to be applied to data packets to determine
183 which packets are to be regarded as link activity, and therefore reset
184 the idle timer, or cause the link to be brought up in demand-dialling
185 mode. This option is useful in conjunction with the
186 \fBidle\fR option if there are packets being sent or received
187 regularly over the link (for example, routing information packets)
188 which would otherwise prevent the link from ever appearing to be idle.
189 The \fIfilter-expression\fR syntax is as described for tcpdump(1),
190 except that qualifiers which are inappropriate for a PPP link, such as
191 \fBether\fR and \fBarp\fR, are not permitted. Generally the filter
192 expression should be enclosed in single-quotes to prevent whitespace
193 in the expression from being interpreted by the shell. This option
194 is currently only available under NetBSD, and then only
195 if both the kernel and pppd were compiled with PPP_FILTER defined.
197 .B allow-ip \fIaddress(es)
198 Allow peers to use the given IP address or subnet without
199 authenticating themselves. The parameter is parsed as for each
200 element of the list of allowed IP addresses in the secrets files (see
201 the AUTHENTICATION section below).
204 Request that the peer compress packets that it sends, using the
205 BSD-Compress scheme, with a maximum code size of \fInr\fR bits, and
206 agree to compress packets sent to the peer with a maximum code size of
207 \fInt\fR bits. If \fInt\fR is not specified, it defaults to the value
208 given for \fInr\fR. Values in the range 9 to 15 may be used for
209 \fInr\fR and \fInt\fR; larger values give better compression but
210 consume more kernel memory for compression dictionaries.
211 Alternatively, a value of 0 for \fInr\fR or \fInt\fR disables
212 compression in the corresponding direction. Use \fInobsdcomp\fR or
213 \fIbsdcomp 0\fR to disable BSD-Compress compression entirely.
216 Use a non-standard hardware flow control (i.e. DTR/CTS) to control
217 the flow of data on the serial port. If neither the \fIcrtscts\fR,
218 the \fInocrtscts\fR, the \fIcdtrcts\fR nor the \fInocdtrcts\fR
219 option is given, the hardware flow control setting for the serial
220 port is left unchanged.
221 Some serial ports (such as Macintosh serial ports) lack a true
222 RTS output. Such serial ports use this mode to implement true
223 bi-directional flow control. The sacrifice is that this flow
224 control mode does not permit using DTR as a modem control line.
226 .B chap-interval \fIn
227 If this option is given, pppd will rechallenge the peer every \fIn\fR
230 .B chap-max-challenge \fIn
231 Set the maximum number of CHAP challenge transmissions to \fIn\fR
235 Set the CHAP restart interval (retransmission timeout for challenges)
236 to \fIn\fR seconds (default 3).
238 .B connect-delay \fIn
239 Wait for up \fIn\fR milliseconds after the connect script finishes for
240 a valid PPP packet from the peer. At the end of this time, or when a
241 valid PPP packet is received from the peer, pppd will commence
242 negotiation by sending its first LCP packet. The default value is
243 1000 (1 second). This wait period only applies if the \fBconnect\fR
244 or \fBpty\fR option is used.
247 Enables connection debugging facilities.
248 If this option is given, pppd will log the contents of all
249 control packets sent or received in a readable form. The packets are
250 logged through syslog with facility \fIdaemon\fR and level
251 \fIdebug\fR. This information can be directed to a file by setting up
252 /etc/syslog.conf appropriately (see syslog.conf(5)).
255 Disable asyncmap negotiation, forcing all control characters to be
256 escaped for both the transmit and the receive direction.
259 Disable MRU [Maximum Receive Unit] negotiation. With this option,
260 pppd will use the default MRU value of 1500 bytes for both the
261 transmit and receive direction.
264 Request that the peer compress packets that it sends, using the
265 Deflate scheme, with a maximum window size of \fI2**nr\fR bytes, and
266 agree to compress packets sent to the peer with a maximum window size
267 of \fI2**nt\fR bytes. If \fInt\fR is not specified, it defaults to
268 the value given for \fInr\fR. Values in the range 9 to 15 may be used
269 for \fInr\fR and \fInt\fR; larger values give better compression but
270 consume more kernel memory for compression dictionaries.
271 Alternatively, a value of 0 for \fInr\fR or \fInt\fR disables
272 compression in the corresponding direction. Use \fInodeflate\fR or
273 \fIdeflate 0\fR to disable Deflate compression entirely. (Note: pppd
274 requests Deflate compression in preference to BSD-Compress if the peer
278 Initiate the link only on demand, i.e. when data traffic is present.
279 With this option, the remote IP address must be specified by the user
280 on the command line or in an options file. Pppd will initially
281 configure the interface and enable it for IP traffic without
282 connecting to the peer. When traffic is available, pppd will
283 connect to the peer and perform negotiation, authentication, etc.
284 When this is completed, pppd will commence passing data packets
285 (i.e., IP packets) across the link.
287 The \fIdemand\fR option implies the \fIpersist\fR option. If this
288 behaviour is not desired, use the \fInopersist\fR option after the
289 \fIdemand\fR option. The \fIidle\fR and \fIholdoff\fR
290 options are also useful in conjuction with the \fIdemand\fR option.
293 Append the domain name \fId\fR to the local host name for authentication
294 purposes. For example, if gethostname() returns the name porsche, but
295 the fully qualified domain name is porsche.Quotron.COM, you could
296 specify \fIdomain Quotron.COM\fR. Pppd would then use the name
297 \fIporsche.Quotron.COM\fR for looking up secrets in the secrets file,
298 and as the default name to send to the peer when authenticating itself
299 to the peer. This option is privileged.
302 With the \fBdryrun\fR option, pppd will print out all the option
303 values which have been set and then exit, after parsing the command
304 line and options files and checking the option values, but before
305 initiating the link. The option values are logged at level info, and
306 also printed to standard output unless the device on standard output
307 is the device that pppd would be using to communicate with the peer.
310 With the \fBdump\fR option, pppd will print out all the option values
311 which have been set. This option is like the \fBdryrun\fR option
312 except that pppd proceeds as normal rather than exiting.
314 .B endpoint \fI<epdisc>
315 Sets the endpoint discriminator sent by the local machine to the peer
316 during multilink negotiation to \fI<epdisc>\fR. The default is to use
317 the MAC address of the first ethernet interface on the system, if any,
318 otherwise the IPv4 address corresponding to the hostname, if any,
319 provided it is not in the multicast or locally-assigned IP address
320 ranges, or the localhost address. The endpoint discriminator can be
321 the string \fBnull\fR or of the form \fItype\fR:\fIvalue\fR, where
322 type is a decimal number or one of the strings \fBlocal\fR, \fBIP\fR,
323 \fBMAC\fR, \fBmagic\fR, or \fBphone\fR. The value is an IP address in
324 dotted-decimal notation for the \fBIP\fR type, or a string of bytes in
325 hexadecimal, separated by periods or colons for the other types. For
326 the MAC type, the value may also be the name of an ethernet or similar
327 network interface. This option is currently only available under
331 When logging the contents of PAP packets, this option causes pppd to
332 exclude the password string from the log. This is the default.
335 Specifies how many seconds to wait before re-initiating the link after
336 it terminates. This option only has any effect if the \fIpersist\fR
337 or \fIdemand\fR option is used. The holdoff period is not applied if
338 the link was terminated because it was idle.
341 Specifies that pppd should disconnect if the link is idle for \fIn\fR
342 seconds. The link is idle when no data packets (i.e. IP packets) are
343 being sent or received. Note: it is not advisable to use this option
344 with the \fIpersist\fR option without the \fIdemand\fR option.
345 If the \fBactive-filter\fR
346 option is given, data packets which are rejected by the specified
347 activity filter also count as the link being idle.
350 With this option, pppd will accept the peer's idea of our local IP
351 address, even if the local IP address was specified in an option.
353 .B ipcp-accept-remote
354 With this option, pppd will accept the peer's idea of its (remote) IP
355 address, even if the remote IP address was specified in an option.
357 .B ipcp-max-configure \fIn
358 Set the maximum number of IPCP configure-request transmissions to
359 \fIn\fR (default 10).
361 .B ipcp-max-failure \fIn
362 Set the maximum number of IPCP configure-NAKs returned before starting
363 to send configure-Rejects instead to \fIn\fR (default 10).
365 .B ipcp-max-terminate \fIn
366 Set the maximum number of IPCP terminate-request transmissions to
370 Set the IPCP restart interval (retransmission timeout) to \fIn\fR
374 Provides an extra parameter to the ip-up and ip-down scripts. If this
375 option is given, the \fIstring\fR supplied is given as the 6th
376 parameter to those scripts.
378 .B ipv6cp-max-configure \fIn
379 Set the maximum number of IPv6CP configure-request transmissions to
380 \fIn\fR (default 10).
382 .B ipv6cp-max-failure \fIn
383 Set the maximum number of IPv6CP configure-NAKs returned before starting
384 to send configure-Rejects instead to \fIn\fR (default 10).
386 .B ipv6cp-max-terminate \fIn
387 Set the maximum number of IPv6CP terminate-request transmissions to
390 .B ipv6cp-restart \fIn
391 Set the IPv6CP restart interval (retransmission timeout) to \fIn\fR
395 Enable the IPXCP and IPX protocols. This option is presently only
396 supported under Linux, and only if your kernel has been configured to
400 Set the IPX network number in the IPXCP configure request frame to
401 \fIn\fR, a hexadecimal number (without a leading 0x). There is no
402 valid default. If this option is not specified, the network number is
403 obtained from the peer. If the peer does not have the network number,
404 the IPX protocol will not be started.
406 .B ipx-node \fIn\fB:\fIm
407 Set the IPX node numbers. The two node numbers are separated from each
408 other with a colon character. The first number \fIn\fR is the local
409 node number. The second number \fIm\fR is the peer's node number. Each
410 node number is a hexadecimal number, at most 10 digits long. The node
411 numbers on the ipx-network must be unique. There is no valid
412 default. If this option is not specified then the node numbers are
413 obtained from the peer.
415 .B ipx-router-name \fI<string>
416 Set the name of the router. This is a string and is sent to the peer
420 Set the routing protocol to be received by this option. More than one
421 instance of \fIipx-routing\fR may be specified. The '\fInone\fR'
422 option (0) may be specified as the only instance of ipx-routing. The
423 values may be \fI0\fR for \fINONE\fR, \fI2\fR for \fIRIP/SAP\fR, and
424 \fI4\fR for \fINLSP\fR.
426 .B ipxcp-accept-local
427 Accept the peer's NAK for the node number specified in the ipx-node
428 option. If a node number was specified, and non-zero, the default is
429 to insist that the value be used. If you include this option then you
430 will permit the peer to override the entry of the node number.
432 .B ipxcp-accept-network
433 Accept the peer's NAK for the network number specified in the
434 ipx-network option. If a network number was specified, and non-zero, the
435 default is to insist that the value be used. If you include this
436 option then you will permit the peer to override the entry of the node
439 .B ipxcp-accept-remote
440 Use the peer's network number specified in the configure request
441 frame. If a node number was specified for the peer and this option was
442 not specified, the peer will be forced to use the value which you have
445 .B ipxcp-max-configure \fIn
446 Set the maximum number of IPXCP configure request frames which the
447 system will send to \fIn\fR. The default is 10.
449 .B ipxcp-max-failure \fIn
450 Set the maximum number of IPXCP NAK frames which the local system will
451 send before it rejects the options. The default value is 3.
453 .B ipxcp-max-terminate \fIn
454 Set the maximum nuber of IPXCP terminate request frames before the
455 local system considers that the peer is not listening to them. The
459 Enable debugging code in the kernel-level PPP driver. The argument
460 values depend on the specific kernel driver, but in general a value of
461 1 will enable general kernel debug messages. (Note that these
462 messages are usually only useful for debugging the kernel driver
463 itself.) For the Linux 2.2.x kernel driver, the value is a sum of
465 enable general debug messages, 2 to request that the contents of
466 received packets be printed, and 4 to request that the contents of
467 transmitted packets be printed. On most systems, messages printed by
468 the kernel are logged by syslog(1) to a file as directed in the
469 /etc/syslog.conf configuration file.
472 Enables pppd to alter kernel settings as appropriate. Under Linux,
473 pppd will enable IP forwarding (i.e. set /proc/sys/net/ipv4/ip_forward
474 to 1) if the \fIproxyarp\fR option is used, and will enable the
475 dynamic IP address option (i.e. set /proc/sys/net/ipv4/ip_dynaddr to
476 1) in demand mode if the local address changes.
478 .B lcp-echo-failure \fIn
479 If this option is given, pppd will presume the peer to be dead
480 if \fIn\fR LCP echo-requests are sent without receiving a valid LCP
481 echo-reply. If this happens, pppd will terminate the
482 connection. Use of this option requires a non-zero value for the
483 \fIlcp-echo-interval\fR parameter. This option can be used to enable
484 pppd to terminate after the physical connection has been broken
485 (e.g., the modem has hung up) in situations where no hardware modem
486 control lines are available.
488 .B lcp-echo-interval \fIn
489 If this option is given, pppd will send an LCP echo-request frame to
490 the peer every \fIn\fR seconds. Normally the peer should respond to
491 the echo-request by sending an echo-reply. This option can be used
492 with the \fIlcp-echo-failure\fR option to detect that the peer is no
495 .B lcp-max-configure \fIn
496 Set the maximum number of LCP configure-request transmissions to
497 \fIn\fR (default 10).
499 .B lcp-max-failure \fIn
500 Set the maximum number of LCP configure-NAKs returned before starting
501 to send configure-Rejects instead to \fIn\fR (default 10).
503 .B lcp-max-terminate \fIn
504 Set the maximum number of LCP terminate-request transmissions to
508 Set the LCP restart interval (retransmission timeout) to \fIn\fR
511 .B linkname \fIname\fR
512 Sets the logical name of the link to \fIname\fR. Pppd will create a
513 file named \fBppp-\fIname\fB.pid\fR in /var/run (or /etc/ppp on some
514 systems) containing its process ID. This can be useful in determining
515 which instance of pppd is responsible for the link to a given peer
516 system. This is a privileged option.
519 Don't use the modem control lines. With this option, pppd will ignore
520 the state of the CD (Carrier Detect) signal from the modem and will
521 not change the state of the DTR (Data Terminal Ready) signal.
524 Send log messages to file descriptor \fIn\fR. Pppd will send log
525 messages to at most one file or file descriptor (as well as sending
526 the log messages to syslog), so this option and the \fBlogfile\fR
527 option are mutually exclusive. The default is for pppd to send log
528 messages to stdout (file descriptor 1), unless the serial port is
529 already open on stdout.
531 .B logfile \fIfilename
532 Append log messages to the file \fIfilename\fR (as well as sending the
533 log messages to syslog). The file is opened with the privileges of
534 the user who invoked pppd, in append mode.
537 Use the system password database for authenticating the peer using
538 PAP, and record the user in the system wtmp file. Note that the peer
539 must have an entry in the /etc/ppp/pap-secrets file as well as the
540 system password database to be allowed access.
543 Terminate the connection when it has been available for network
544 traffic for \fIn\fR seconds (i.e. \fIn\fR seconds after the first
545 network control protocol comes up).
548 Terminate after \fIn\fR consecutive failed connection attempts. A
549 value of 0 means no limit. The default value is 10.
552 Use the modem control lines. This option is the default. With this
553 option, pppd will wait for the CD (Carrier Detect) signal from the
554 modem to be asserted when opening the serial device (unless a connect
555 script is specified), and it will drop the DTR (Data Terminal Ready)
556 signal briefly when the connection is terminated and before executing
557 the connect script. On Ultrix, this option implies hardware flow
558 control, as for the \fIcrtscts\fR option.
561 Enables the use of PPP multilink; this is an alias for the `multilink'
562 option. This option is currently only available under Linux.
565 Allow MPPE to use stateful mode. Stateless mode is still attempted first.
566 The default is to disallow stateful mode.
569 Enables the use of short (12-bit) sequence numbers in multilink
570 headers, as opposed to 24-bit sequence numbers. This option is only
571 available under Linux, and only has any effect if multilink is
572 enabled (see the multilink option).
575 Sets the Maximum Reconstructed Receive Unit to \fIn\fR. The MRRU is
576 the maximum size for a received packet on a multilink bundle, and is
577 analogous to the MRU for the individual links. This option is
578 currently only available under Linux, and only has any effect if
579 multilink is enabled (see the multilink option).
582 If pppd is acting as a server for Microsoft Windows clients, this
583 option allows pppd to supply one or two DNS (Domain Name Server)
584 addresses to the clients. The first instance of this option specifies
585 the primary DNS address; the second instance (if given) specifies the
586 secondary DNS address. (This option was present in some older
587 versions of pppd under the name \fBdns-addr\fR.)
590 If pppd is acting as a server for Microsoft Windows or "Samba"
591 clients, this option allows pppd to supply one or two WINS (Windows
592 Internet Name Services) server addresses to the clients. The first
593 instance of this option specifies the primary WINS address; the second
594 instance (if given) specifies the secondary WINS address.
597 Enables the use of the PPP multilink protocol. If the peer also
598 supports multilink, then this link can become part of a bundle between
599 the local system and the peer. If there is an existing bundle to the
600 peer, pppd will join this link to that bundle, otherwise pppd will
601 create a new bundle. See the MULTILINK section below. This option is
602 currently only available under Linux.
605 Set the name of the local system for authentication purposes to
606 \fIname\fR. This is a privileged option. With this option, pppd will
607 use lines in the secrets files which have \fIname\fR as the second
608 field when looking for a secret to use in authenticating the peer. In
609 addition, unless overridden with the \fIuser\fR option, \fIname\fR
610 will be used as the name to send to the peer when authenticating the
611 local system to the peer. (Note that pppd does not append the domain
615 Set the interface netmask to \fIn\fR, a 32 bit netmask in "decimal dot"
616 notation (e.g. 255.255.255.0). If this option is given, the value
617 specified is ORed with the default netmask. The default netmask is
618 chosen based on the negotiated remote IP address; it is the
619 appropriate network mask for the class of the remote IP address, ORed
620 with the netmasks for any non point-to-point network interfaces in the
621 system which are on the same network. (Note: on some platforms, pppd
622 will always use 255.255.255.255 for the netmask, if that is the only
623 appropriate value for a point-to-point interface.)
626 Disable Address/Control compression in both directions (send and
630 Do not require the peer to authenticate itself. This option is
634 Disables BSD-Compress compression; \fBpppd\fR will not request or
635 agree to compress packets using the BSD-Compress scheme.
638 Disable CCP (Compression Control Protocol) negotiation. This option
639 should only be required if the peer is buggy and gets confused by
640 requests from pppd for CCP negotiation.
643 Disable hardware flow control (i.e. RTS/CTS) on the serial port.
644 If neither the \fIcrtscts\fR nor the \fInocrtscts\fR nor the
645 \fIcdtrcts\fR nor the \fInocdtrcts\fR option is given, the hardware
646 flow control setting for the serial port is left unchanged.
649 This option is a synonym for \fInocrtscts\fR. Either of these options will
650 disable both forms of hardware flow control.
653 Disable the \fIdefaultroute\fR option. The system administrator who
654 wishes to prevent users from creating default routes with pppd
655 can do so by placing this option in the /etc/ppp/options file.
658 Disables Deflate compression; pppd will not request or agree to
659 compress packets using the Deflate scheme.
662 Don't detach from the controlling terminal. Without this option, if a
663 serial device other than the terminal on the standard input is
664 specified, pppd will fork to become a background process.
667 Disables pppd from sending an endpoint discriminator to the peer or
668 accepting one from the peer (see the MULTILINK section below). This
669 option should only be required if the peer is buggy.
672 Disable IPCP negotiation and IP communication. This option should
673 only be required if the peer is buggy and gets confused by requests
674 from pppd for IPCP negotiation.
677 Disable IPv6CP negotiation and IPv6 communication. This option should
678 only be required if the peer is buggy and gets confused by requests
679 from pppd for IPv6CP negotiation.
682 Disables the default behaviour when no local IP address is specified,
683 which is to determine (if possible) the local IP address from the
684 hostname. With this option, the peer will have to supply the local IP
685 address during IPCP negotiation (unless it specified explicitly on the
686 command line or in an options file).
689 Disable the IPXCP and IPX protocols. This option should only be
690 required if the peer is buggy and gets confused by requests from pppd
691 for IPXCP negotiation.
694 Opposite of the \fIktune\fR option; disables pppd from changing system
698 Do not send log messages to a file or file descriptor. This option
699 cancels the \fBlogfd\fR and \fBlogfile\fR options.
702 Disable magic number negotiation. With this option, pppd cannot
703 detect a looped-back line. This option should only be needed if the
707 Disables the use of PPP multilink. This option is currently only
708 available under Linux.
711 Disables MPPE (Microsoft Point to Point Encryption). This is the default.
714 Disable 40\-bit encryption with MPPE.
717 Disable 128\-bit encryption with MPPE.
720 Disabled MPPE stateful mode. This is the default.
723 Disables the use of short (12-bit) sequence numbers in the PPP
724 multilink protocol, forcing the use of 24-bit sequence numbers. This
725 option is currently only available under Linux, and only has any
726 effect if multilink is enabled.
729 Disables the use of PPP multilink. This option is currently only
730 available under Linux.
733 Disable protocol field compression negotiation in both the receive and
734 the transmit direction.
737 Exit once a connection has been made and terminated. This is the
738 default unless the \fIpersist\fR or \fIdemand\fR option has been
742 Do not accept or agree to Predictor-1 compression.
745 Disable the \fIproxyarp\fR option. The system administrator who
746 wishes to prevent users from creating proxy ARP entries with pppd can
747 do so by placing this option in the /etc/ppp/options file.
750 Normally, pppd requires a terminal device. With this option, pppd
751 will allocate itself a pseudo-tty master/slave pair and use the slave
752 as its terminal device. Pppd will create a child process to act as a
753 `character shunt' to transfer characters between the pseudo-tty master
754 and its standard input and output. Thus pppd will transmit characters
755 on its standard output and receive characters on its standard input
756 even if they are not terminal devices. This option increases the
757 latency and CPU overhead of transferring data over the ppp interface
758 as all of the characters sent and received must flow through the
759 character shunt process. An explicit device name may not be given if
763 Disable Van Jacobson style TCP/IP header compression in both the
764 transmit and the receive direction.
767 Disable the connection-ID compression option in Van Jacobson style
768 TCP/IP header compression. With this option, pppd will not omit the
769 connection-ID byte from Van Jacobson compressed TCP/IP headers, nor
770 ask the peer to do so.
773 Indicates that all secrets in the /etc/ppp/pap-secrets file which are
774 used for checking the identity of the peer are encrypted, and thus
775 pppd should not accept a password which, before encryption, is
776 identical to the secret from the /etc/ppp/pap-secrets file.
778 .B pap-max-authreq \fIn
779 Set the maximum number of PAP authenticate-request transmissions to
780 \fIn\fR (default 10).
783 Set the PAP restart interval (retransmission timeout) to \fIn\fR
787 Set the maximum time that pppd will wait for the peer to authenticate
788 itself with PAP to \fIn\fR seconds (0 means no limit).
790 .B pass-filter \fIfilter-expression
791 Specifies a packet filter to applied to data packets being sent or
792 received to determine which packets should be allowed to pass.
793 Packets which are rejected by the filter are silently discarded. This
794 option can be used to prevent specific network daemons (such as
795 routed) using up link bandwidth, or to provide a basic firewall
797 The \fIfilter-expression\fR syntax is as described for tcpdump(1),
798 except that qualifiers which are inappropriate for a PPP link, such as
799 \fBether\fR and \fBarp\fR, are not permitted. Generally the filter
800 expression should be enclosed in single-quotes to prevent whitespace
801 in the expression from being interpreted by the shell. Note that it
802 is possible to apply different constraints to incoming and outgoing
803 packets using the \fBinbound\fR and \fBoutbound\fR qualifiers. This
804 option is currently only available under NetBSD, and then only if both
805 the kernel and pppd were compiled with PPP_FILTER defined.
808 Do not exit after a connection is terminated; instead try to reopen
809 the connection. The \fBmaxfail\fR option still has an effect on
810 persistent connections.
812 .B plugin \fIfilename
813 Load the shared library object file \fIfilename\fR as a plugin. This
814 is a privileged option. If \fIfilename\fR does not contain a slash
815 (/), pppd will look in the \fB/usr/lib/pppd/\fIversion\fR directory
816 for the plugin, where
817 \fIversion\fR is the version number of pppd (for example, 2.4.2).
820 Request that the peer compress frames that it sends using Predictor-1
821 compression, and agree to compress transmitted frames with Predictor-1
822 if requested. This option has no effect unless the kernel driver
823 supports Predictor-1 compression.
825 .B privgroup \fIgroup-name
826 Allows members of group \fIgroup-name\fR to use privileged options.
827 This is a privileged option. Use of this option requires care as
828 there is no guarantee that members of \fIgroup-name\fR cannot use pppd
829 to become root themselves. Consider it equivalent to putting the
830 members of \fIgroup-name\fR in the kmem or disk group.
833 Add an entry to this system's ARP [Address Resolution Protocol] table
834 with the IP address of the peer and the Ethernet address of this
835 system. This will have the effect of making the peer appear to other
836 systems to be on the local ethernet.
839 Specifies that the command \fIscript\fR is to be used to communicate
840 rather than a specific terminal device. Pppd will allocate itself a
841 pseudo-tty master/slave pair and use the slave as its terminal
842 device. The \fIscript\fR will be run in a child process with the
843 pseudo-tty master as its standard input and output. An explicit
844 device name may not be given if this option is used. (Note: if the
845 \fIrecord\fR option is used in conjuction with the \fIpty\fR option,
846 the child process will have pipes on its standard input and output.)
849 With this option, pppd will accept all control characters from the
850 peer, including those marked in the receive asyncmap. Without this
851 option, pppd will discard those characters as specified in RFC1662.
852 This option should only be needed if the peer is buggy.
854 .B record \fIfilename
855 Specifies that pppd should record all characters sent and received to
856 a file named \fIfilename\fR. This file is opened in append mode,
857 using the user's user-ID and permissions. This option is implemented
858 using a pseudo-tty and a process to transfer characters between the
859 pseudo-tty and the real serial device, so it will increase the latency
860 and CPU overhead of transferring data over the ppp interface. The
861 characters are stored in a tagged format with timestamps, which can be
862 displayed in readable form using the pppdump(8) program.
864 .B remotename \fIname
865 Set the assumed name of the remote system for authentication purposes
869 With this option, pppd will not agree to authenticate itself to the
873 With this option, pppd will not agree to authenticate itself to the
877 With this option, pppd will not agree to authenticate itself to the
878 peer using MS-CHAPv2.
881 With this option, pppd will not agree to authenticate itself to the
885 Require the peer to authenticate itself using CHAP [Challenge
886 Handshake Authentication Protocol] authentication.
889 Require the use of MPPE (Microsoft Point to Point Encryption). This
890 option disables all other compression types. This option enables
891 both 40\-bit and 128\-bit encryption. In order for MPPE to successfully
892 come up, you must have authenticated with either MS-CHAP or MS-CHAPv2.
893 This option is presently only supported under Linux, and only if your
894 kernel has been configured to include MPPE support.
897 Require the use of MPPE, with 40\-bit encryption.
900 Require the use of MPPE, with 128\-bit encryption.
903 Require the peer to authenticate itself using MS-CHAP [Microsft Challenge
904 Handshake Authentication Protocol] authentication.
907 Require the peer to authenticate itself using MS-CHAPv2 [Microsft Challenge
908 Handshake Authentication Protocol, Version 2] authentication.
911 Require the peer to authenticate itself using PAP [Password
912 Authentication Protocol] authentication.
915 When logging the contents of PAP packets, this option causes pppd to
916 show the password string in the log message.
919 With this option, pppd will not transmit LCP packets to initiate a
920 connection until a valid LCP packet is received from the peer (as for
921 the `passive' option with ancient versions of pppd).
924 Use synchronous HDLC serial encoding instead of asynchronous.
925 The device used by pppd with this option must have sync support.
926 Currently supports Microgate SyncLink adapters
927 under Linux and FreeBSD 2.2.8 and later.
930 With this option, pppd will detach from its controlling terminal once
931 it has successfully established the ppp connection (to the point where
932 the first network control protocol, usually the IP control protocol,
936 Enforce the use of the hostname (with domain name appended, if given)
937 as the name of the local system for authentication purposes (overrides
938 the \fIname\fR option). This option is not normally needed since the
939 \fIname\fR option is privileged.
942 Ask the peer for up to 2 DNS server addresses. The addresses supplied
943 by the peer (if any) are passed to the /etc/ppp/ip-up script in the
944 environment variables DNS1 and DNS2. In addition, pppd will create an
945 /etc/ppp/resolv.conf file containing one or two nameserver lines with
946 the address(es) supplied by the peer.
949 Sets the name used for authenticating the local system to the peer to
953 Sets the number of connection slots to be used by the Van Jacobson
954 TCP/IP header compression and decompression code to \fIn\fR, which
955 must be between 2 and 16 (inclusive).
958 Run the executable or shell command specified by \fIscript\fR before
959 initiating PPP negotiation, after the connect script (if any) has
960 completed. A value for this option from a privileged source cannot be
961 overridden by a non-privileged user.
964 Use software flow control (i.e. XON/XOFF) to control the flow of data on
967 Options can be taken from files as well as the command line. Pppd
968 reads options from the files /etc/ppp/options, ~/.ppprc and
969 /etc/ppp/options.\fIttyname\fR (in that order) before processing the
970 options on the command line. (In fact, the command-line options are
971 scanned to find the terminal name before the options.\fIttyname\fR
972 file is read.) In forming the name of the options.\fIttyname\fR file,
973 the initial /dev/ is removed from the terminal name, and any remaining
974 / characters are replaced with dots.
976 An options file is parsed into a series of words, delimited by
977 whitespace. Whitespace can be included in a word by enclosing the
978 word in double-quotes ("). A backslash (\\) quotes the following character.
979 A hash (#) starts a comment, which continues until the end of the
980 line. There is no restriction on using the \fIfile\fR or \fIcall\fR
981 options within an options file.
984 provides system administrators with sufficient access control that PPP
985 access to a server machine can be provided to legitimate users without
986 fear of compromising the security of the server or the network it's
987 on. This control is provided through restrictions on which IP
988 addresses the peer may use, based on its authenticated identity (if
989 any), and through restrictions on which options a non-privileged user
990 may use. Several of pppd's options are privileged, in particular
991 those which permit potentially insecure configurations; these options
992 are only accepted in files which are under the control of the system
993 administrator, or if pppd is being run by root.
995 The default behaviour of pppd is to allow an unauthenticated peer to
996 use a given IP address only if the system does not already have a
997 route to that IP address. For example, a system with a
998 permanent connection to the wider internet will normally have a
999 default route, and thus all peers will have to authenticate themselves
1000 in order to set up a connection. On such a system, the \fIauth\fR
1001 option is the default. On the other hand, a system where the
1002 PPP link is the only connection to the internet will not normally have
1003 a default route, so the peer will be able to use almost any IP address
1004 without authenticating itself.
1006 As indicated above, some security-sensitive options are privileged,
1007 which means that they may not be used by an ordinary non-privileged
1008 user running a setuid-root pppd, either on the command line, in the
1009 user's ~/.ppprc file, or in an options file read using the \fIfile\fR
1010 option. Privileged options may be used in /etc/ppp/options file or in
1011 an options file read using the \fIcall\fR option. If pppd is being
1012 run by the root user, privileged options can be used without
1015 When opening the device, pppd uses either the invoking user's user ID
1016 or the root UID (that is, 0), depending on whether the device name was
1017 specified by the user or the system administrator. If the device name
1018 comes from a privileged source, that is, /etc/ppp/options or an
1019 options file read using the \fIcall\fR option, pppd uses full root
1020 privileges when opening the device. Thus, by creating an appropriate
1021 file under /etc/ppp/peers, the system administrator can allow users to
1022 establish a ppp connection via a device which they would not normally
1023 have permission to access. Otherwise pppd uses the invoking user's
1024 real UID when opening the device.
1026 Authentication is the process whereby one peer convinces the other of
1027 its identity. This involves the first peer sending its name to the
1028 other, together with some kind of secret information which could only
1029 come from the genuine authorized user of that name. In such an
1030 exchange, we will call the first peer the "client" and the other the
1031 "server". The client has a name by which it identifies itself to the
1032 server, and the server also has a name by which it identifies itself
1033 to the client. Generally the genuine client shares some secret (or
1034 password) with the server, and authenticates itself by proving that it
1035 knows that secret. Very often, the names used for authentication
1036 correspond to the internet hostnames of the peers, but this is not
1039 At present, pppd supports two authentication protocols: the Password
1040 Authentication Protocol (PAP) and the Challenge Handshake
1041 Authentication Protocol (CHAP). PAP involves the client sending its
1042 name and a cleartext password to the server to authenticate itself.
1043 In contrast, the server initiates the CHAP authentication exchange by
1044 sending a challenge to the client (the challenge packet includes the
1045 server's name). The client must respond with a response which
1046 includes its name plus a hash value derived from the shared secret and
1047 the challenge, in order to prove that it knows the secret.
1049 The PPP protocol, being symmetrical, allows both peers to require the
1050 other to authenticate itself. In that case, two separate and
1051 independent authentication exchanges will occur. The two exchanges
1052 could use different authentication protocols, and in principle,
1053 different names could be used in the two exchanges.
1055 The default behaviour of pppd is to agree to authenticate if
1056 requested, and to not require authentication from the peer. However,
1057 pppd will not agree to authenticate itself with a particular protocol
1058 if it has no secrets which could be used to do so.
1060 Pppd stores secrets for use in authentication in secrets
1061 files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for
1062 CHAP/MS-CHAP/MS-CHAPv2).
1063 Both secrets files have the same format. The secrets files can
1064 contain secrets for pppd to use in authenticating itself to other
1065 systems, as well as secrets for pppd to use when authenticating other
1068 Each line in a secrets file contains one secret. A given secret is
1069 specific to a particular combination of client and server - it can
1070 only be used by that client to authenticate itself to that server.
1071 Thus each line in a secrets file has at least 3 fields: the name of
1072 the client, the name of the server, and the secret. These fields may
1073 be followed by a list of the IP addresses that the specified client
1074 may use when connecting to the specified server.
1076 A secrets file is parsed into words as for a options file, so the
1077 client name, server name and secrets fields must each be one word,
1078 with any embedded spaces or other special characters quoted or
1079 escaped. Note that case is significant in the client and server names
1082 If the secret starts with an `@', what follows is assumed to be the
1083 name of a file from which to read the secret. A "*" as the client or
1084 server name matches any name. When selecting a secret, pppd takes the
1085 best match, i.e. the match with the fewest wildcards.
1087 Any following words on the same line are taken to be a list of
1088 acceptable IP addresses for that client. If there are only 3 words on
1089 the line, or if the first word is "-", then all IP addresses are
1090 disallowed. To allow any address, use "*". A word starting with "!"
1091 indicates that the specified address is \fInot\fR acceptable. An
1092 address may be followed by "/" and a number \fIn\fR, to indicate a
1093 whole subnet, i.e. all addresses which have the same value in the most
1094 significant \fIn\fR bits. In this form, the address may be followed
1095 by a plus sign ("+") to indicate that one address from the subnet is
1096 authorized, based on the ppp network interface unit number in use.
1097 In this case, the host part of the address will be set to the unit
1100 Thus a secrets file contains both secrets for use in authenticating
1101 other hosts, plus secrets which we use for authenticating ourselves to
1102 others. When pppd is authenticating the peer (checking the peer's
1103 identity), it chooses a secret with the peer's name in the first
1104 field and the name of the local system in the second field. The
1105 name of the local system defaults to the hostname, with the domain
1106 name appended if the \fIdomain\fR option is used. This default can be
1107 overridden with the \fIname\fR option, except when the
1108 \fIusehostname\fR option is used.
1110 When pppd is choosing a secret to use in authenticating itself to the
1111 peer, it first determines what name it is going to use to identify
1112 itself to the peer. This name can be specified by the user with the
1113 \fIuser\fR option. If this option is not used, the name defaults to
1114 the name of the local system, determined as described in the previous
1115 paragraph. Then pppd looks for a secret with this name in the first
1116 field and the peer's name in the second field. Pppd will know the
1117 name of the peer if CHAP authentication is being used, because the
1118 peer will have sent it in the challenge packet. However, if PAP is being
1119 used, pppd will have to determine the peer's name from the options
1120 specified by the user. The user can specify the peer's name directly
1121 with the \fIremotename\fR option. Otherwise, if the remote IP address
1122 was specified by a name (rather than in numeric form), that name will
1123 be used as the peer's name. Failing that, pppd will use the null
1124 string as the peer's name.
1126 When authenticating the peer with PAP, the supplied password is first
1127 compared with the secret from the secrets file. If the password
1128 doesn't match the secret, the password is encrypted using crypt() and
1129 checked against the secret again. Thus secrets for authenticating the
1130 peer can be stored in encrypted form if desired. If the
1131 \fIpapcrypt\fR option is given, the first (unencrypted) comparison is
1132 omitted, for better security.
1134 Furthermore, if the \fIlogin\fR option was specified, the username and
1135 password are also checked against the system password database. Thus,
1136 the system administrator can set up the pap-secrets file to allow PPP
1137 access only to certain users, and to restrict the set of IP addresses
1138 that each user can use. Typically, when using the \fIlogin\fR option,
1139 the secret in /etc/ppp/pap-secrets would be "", which will match any
1140 password supplied by the peer. This avoids the need to have the same
1141 secret in two places.
1143 Authentication must be satisfactorily completed before IPCP (or any
1144 other Network Control Protocol) can be started. If the peer is
1145 required to authenticate itself, and fails to do so, pppd will
1146 terminated the link (by closing LCP). If IPCP negotiates an
1147 unacceptable IP address for the remote host, IPCP will be closed. IP
1148 packets can only be sent or received when IPCP is open.
1150 In some cases it is desirable to allow some hosts which can't
1151 authenticate themselves to connect and use one of a restricted set of
1152 IP addresses, even when the local host generally requires
1153 authentication. If the peer refuses to authenticate itself when
1154 requested, pppd takes that as equivalent to authenticating with PAP
1155 using the empty string for the username and password. Thus, by adding
1156 a line to the pap-secrets file which specifies the empty string for
1157 the client and password, it is possible to allow restricted access to
1158 hosts which refuse to authenticate themselves.
1161 When IPCP negotiation is completed successfully, pppd will inform the
1162 kernel of the local and remote IP addresses for the ppp interface.
1163 This is sufficient to create a host route to the remote end of the
1164 link, which will enable the peers to exchange IP packets.
1165 Communication with other machines generally requires further
1166 modification to routing tables and/or ARP (Address Resolution
1167 Protocol) tables. In most cases the \fIdefaultroute\fR and/or
1168 \fIproxyarp\fR options are sufficient for this, but in some cases
1169 further intervention is required. The /etc/ppp/ip-up script can be
1172 Sometimes it is desirable to add a default route through the remote
1173 host, as in the case of a machine whose only connection to the
1174 Internet is through the ppp interface. The \fIdefaultroute\fR option
1175 causes pppd to create such a default route when IPCP comes up, and
1176 delete it when the link is terminated.
1178 In some cases it is desirable to use proxy ARP, for example on a
1179 server machine connected to a LAN, in order to allow other hosts to
1180 communicate with the remote host. The \fIproxyarp\fR option causes
1181 pppd to look for a network interface on the same subnet as the remote
1182 host (an interface supporting broadcast and ARP, which is up and not a
1183 point-to-point or loopback interface). If found, pppd creates a
1184 permanent, published ARP entry with the IP address of the remote host
1185 and the hardware address of the network interface found.
1187 When the \fIdemand\fR option is used, the interface IP addresses have
1188 already been set at the point when IPCP comes up. If pppd has not
1189 been able to negotiate the same addresses that it used to configure
1190 the interface (for example when the peer is an ISP that uses dynamic
1191 IP address assignment), pppd has to change the interface IP addresses
1192 to the negotiated addresses. This may disrupt existing connections,
1193 and the use of demand dialling with peers that do dynamic IP address
1194 assignment is not recommended.
1196 Multilink PPP provides the capability to combine two or more PPP links
1197 between a pair of machines into a single `bundle', which appears as a
1198 single virtual PPP link which has the combined bandwidth of the
1199 individual links. Currently, multilink PPP is only supported under
1202 Pppd detects that the link it is controlling is connected to the same
1203 peer as another link using the peer's endpoint discriminator and the
1204 authenticated identity of the peer (if it authenticates itself). The
1205 endpoint discriminator is a block of data which is hopefully unique
1206 for each peer. Several types of data can be used, including
1207 locally-assigned strings of bytes, IP addresses, MAC addresses,
1208 randomly strings of bytes, or E-164 phone numbers. The endpoint
1209 discriminator sent to the peer by pppd can be set using the endpoint
1212 In circumstances the peer may send no endpoint discriminator or a
1213 non-unique value. The optional bundle option adds an extra string
1214 which is added to the peer's endpoint discriminator and authenticated
1215 identity when matching up links to be joined together in a bundle.
1216 The bundle option can also be used to allow the establishment of
1217 multiple bundles between the local system and the peer. Pppd uses a
1218 TDB database in /var/run/pppd.tdb to match up links.
1220 Assuming that multilink is enabled and the peer is willing to
1221 negotiate multilink, then when pppd is invoked to bring up the first
1222 link to the peer, it will detect that no other link is connected to
1223 the peer and create a new bundle, that is, another ppp network
1224 interface unit. When another pppd is invoked to bring up another link
1225 to the peer, it will detect the existing bundle and join its link to
1226 it. Currently, if the first pppd terminates (for example, because of
1227 a hangup or a received signal) the bundle is destroyed.
1230 The following examples assume that the /etc/ppp/options file contains
1231 the \fIauth\fR option (as in the default /etc/ppp/options file in the
1234 Probably the most common use of pppd is to dial out to an ISP. This
1235 can be done with a command such as
1239 where the /etc/ppp/peers/isp file is set up by the system
1240 administrator to contain something like this:
1244 connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
1248 In this example, we are using chat to dial the ISP's modem and go
1249 through any logon sequence required. The /etc/ppp/chat-isp file
1250 contains the script used by chat; it could for example contain
1251 something like this:
1263 ABORT "Username/Password Incorrect"
1271 "name:" "^Umyuserid"
1273 "word:" "\\qmypassword"
1279 See the chat(8) man page for details of chat scripts.
1281 Pppd can also be used to provide a dial-in ppp service for users. If
1282 the users already have login accounts, the simplest way to set up the
1283 ppp service is to let the users log in to their accounts and run pppd
1284 (installed setuid-root) with a command such as
1288 To allow a user to use the PPP facilities, you need to allocate an IP
1289 address for that user's machine and create an entry in
1290 /etc/ppp/pap-secrets or /etc/ppp/chap-secrets (depending on which
1291 authentication method the PPP implementation on the user's machine
1292 supports), so that the user's
1293 machine can authenticate itself. For example, if Joe has a machine
1294 called "joespc" which is to be allowed to dial in to the machine
1295 called "server" and use the IP address joespc.my.net, you would add an
1296 entry like this to /etc/ppp/pap-secrets or /etc/ppp/chap-secrets:
1298 joespc server "joe's secret" joespc.my.net
1300 Alternatively, you can create a username called (for example) "ppp",
1301 whose login shell is pppd and whose home directory is /etc/ppp.
1302 Options to be used when pppd is run this way can be put in
1305 If your serial connection is any more complicated than a piece of
1306 wire, you may need to arrange for some control characters to be
1307 escaped. In particular, it is often useful to escape XON (^Q) and
1308 XOFF (^S), using \fIasyncmap a0000\fR. If the path includes a telnet,
1309 you probably should escape ^] as well (\fIasyncmap 200a0000\fR). If
1310 the path includes an rlogin, you will need to use the \fIescape ff\fR
1311 option on the end which is running the rlogin client, since many
1312 rlogin implementations are not transparent; they will remove the
1313 sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the
1317 Messages are sent to the syslog daemon using facility LOG_DAEMON.
1318 (This can be overriden by recompiling pppd with the macro
1319 LOG_PPP defined as the desired facility.) In order to see the error
1320 and debug messages, you will need to edit your /etc/syslog.conf file
1321 to direct the messages to the desired output device or file.
1323 The \fIdebug\fR option causes the contents of all control packets sent
1324 or received to be logged, that is, all LCP, PAP, CHAP or IPCP packets.
1325 This can be useful if the PPP negotiation does not succeed or if
1326 authentication fails.
1327 If debugging is enabled at compile time, the \fIdebug\fR option also
1328 causes other debugging messages to be logged.
1330 Debugging can also be enabled or disabled by sending a SIGUSR1 signal
1331 to the pppd process. This signal acts as a toggle.
1333 The exit status of pppd is set to indicate whether any error was
1334 detected, or the reason for the link being terminated. The values
1338 Pppd has detached, or otherwise the connection was successfully
1339 established and terminated at the peer's request.
1342 An immediately fatal error of some kind occurred, such as an essential
1343 system call failing, or running out of virtual memory.
1346 An error was detected in processing the options given, such as two
1347 mutually exclusive options being used.
1350 Pppd is not setuid-root and the invoking user is not root.
1353 The kernel does not support PPP, for example, the PPP kernel driver is
1354 not included or cannot be loaded.
1357 Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP
1361 The serial port could not be locked.
1364 The serial port could not be opened.
1367 The connect script failed (returned a non-zero exit status).
1370 The command specified as the argument to the \fIpty\fR option could
1374 The PPP negotiation failed, that is, it didn't reach the point where
1375 at least one network protocol (e.g. IP) was running.
1378 The peer system failed (or refused) to authenticate itself.
1381 The link was established successfully and terminated because it was
1385 The link was established successfully and terminated because the
1386 connect time limit was reached.
1389 Callback was negotiated and an incoming call should arrive shortly.
1392 The link was terminated because the peer is not responding to echo
1396 The link was terminated by the modem hanging up.
1399 The PPP negotiation failed because serial loopback was detected.
1402 The init script failed (returned a non-zero exit status).
1405 We failed to authenticate ourselves to the peer.
1407 Pppd invokes scripts at various stages in its processing which can be
1408 used to perform site-specific ancillary processing. These scripts are
1409 usually shell scripts, but could be executable code files instead.
1410 Pppd does not wait for the scripts to finish. The scripts are
1411 executed as root (with the real and effective user-id set to 0), so
1412 that they can do things such as update routing tables or run
1413 privileged daemons. Be careful that the contents of these scripts do
1414 not compromise your system's security. Pppd runs the scripts with
1415 standard input, output and error redirected to /dev/null, and with an
1416 environment that is empty except for some environment variables that
1417 give information about the link. The environment variables that pppd
1421 The name of the serial tty device being used.
1424 The name of the network interface being used.
1427 The IP address for the local end of the link. This is only set when
1431 The IP address for the remote end of the link. This is only set when
1435 The authenticated name of the peer. This is only set if the peer
1436 authenticates itself.
1439 The baud rate of the tty device.
1442 The real user-id of the user who invoked pppd.
1445 The username of the real user-id that invoked pppd. This is always set.
1447 For the ip-down and auth-down scripts, pppd also sets the following
1448 variables giving statistics for the connection:
1451 The number of seconds from when the PPP negotiation started until the
1452 connection was terminated.
1455 The number of bytes sent (at the level of the serial port) during the
1459 The number of bytes received (at the level of the serial port) during
1463 The logical name of the link, set with the \fIlinkname\fR option.
1465 Pppd invokes the following scripts, if they exist. It is not an error
1466 if they don't exist.
1469 A program or script which is executed after the remote system
1470 successfully authenticates itself. It is executed with the parameters
1472 \fIinterface-name peer-name user-name tty-device speed\fR
1474 Note that this script is not executed if the peer doesn't authenticate
1475 itself, for example when the \fInoauth\fR option is used.
1477 .B /etc/ppp/auth-down
1478 A program or script which is executed when the link goes down, if
1479 /etc/ppp/auth-up was previously executed. It is executed in the same
1480 manner with the same parameters as /etc/ppp/auth-up.
1483 A program or script which is executed when the link is available for
1484 sending and receiving IP packets (that is, IPCP has come up). It is
1485 executed with the parameters
1487 \fIinterface-name tty-device speed local-IP-address
1488 remote-IP-address ipparam\fR
1491 A program or script which is executed when the link is no longer
1492 available for sending and receiving IP packets. This script can be
1493 used for undoing the effects of the /etc/ppp/ip-up script. It is
1494 invoked in the same manner and with the same parameters as the ip-up
1498 Like /etc/ppp/ip-up, except that it is executed when the link is available
1499 for sending and receiving IPv6 packets. It is executed with the parameters
1501 \fIinterface-name tty-device speed local-link-local-address
1502 remote-link-local-address ipparam\fR
1504 .B /etc/ppp/ipv6-down
1505 Similar to /etc/ppp/ip-down, but it is executed when IPv6 packets can no
1506 longer be transmitted on the link. It is executed with the same parameters
1507 as the ipv6-up script.
1510 A program or script which is executed when the link is available for
1511 sending and receiving IPX packets (that is, IPXCP has come up). It is
1512 executed with the parameters
1514 \fIinterface-name tty-device speed network-number local-IPX-node-address
1515 remote-IPX-node-address local-IPX-routing-protocol remote-IPX-routing-protocol
1516 local-IPX-router-name remote-IPX-router-name ipparam pppd-pid\fR
1518 The local-IPX-routing-protocol and remote-IPX-routing-protocol field
1519 may be one of the following:
1521 NONE to indicate that there is no routing protocol
1523 RIP to indicate that RIP/SAP should be used
1525 NLSP to indicate that Novell NLSP should be used
1527 RIP NLSP to indicate that both RIP/SAP and NLSP should be used
1529 .B /etc/ppp/ipx-down
1530 A program or script which is executed when the link is no longer
1531 available for sending and receiving IPX packets. This script can be
1532 used for undoing the effects of the /etc/ppp/ipx-up script. It is
1533 invoked in the same manner and with the same parameters as the ipx-up
1537 .B /var/run/ppp\fIn\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp\fIn\fB.pid \fR(others)
1538 Process-ID for pppd process on ppp interface unit \fIn\fR.
1540 .B /var/run/ppp-\fIname\fB.pid \fR(BSD or Linux),
1541 \fB/etc/ppp/ppp-\fIname\fB.pid \fR(others)
1542 Process-ID for pppd process for logical link \fIname\fR (see the
1543 \fIlinkname\fR option).
1545 .B /etc/ppp/pap-secrets
1546 Usernames, passwords and IP addresses for PAP authentication. This
1547 file should be owned by root and not readable or writable by any other
1548 user. Pppd will log a warning if this is not the case.
1550 .B /etc/ppp/chap-secrets
1551 Names, secrets and IP addresses for CHAP/MS-CHAP/MS-CHAPv2 authentication.
1552 As for /etc/ppp/pap-secrets, this file should be owned by root and not
1553 readable or writable by any other user. Pppd will log a warning if
1554 this is not the case.
1557 System default options for pppd, read before user default options or
1558 command-line options.
1561 User default options, read before /etc/ppp/options.\fIttyname\fR.
1563 .B /etc/ppp/options.\fIttyname
1564 System default options for the serial port being used, read after
1565 ~/.ppprc. In forming the \fIttyname\fR part of this
1566 filename, an initial /dev/ is stripped from the port name (if
1567 present), and any slashes in the remaining part are converted to
1571 A directory containing options files which may contain privileged
1572 options, even if pppd was invoked by a user other than root. The
1573 system administrator can create options files in this directory to
1574 permit non-privileged users to dial out without requiring the peer to
1575 authenticate, but only to certain trusted peers.
1580 \fICompressing TCP/IP headers for low-speed serial links.\fR
1585 .I The MD5 Message-Digest Algorithm.
1590 .I PPP Internet Protocol Control Protocol (IPCP).
1594 Lloyd, B.; Simpson, W.A.
1595 .I PPP authentication protocols.
1600 .I The Point\-to\-Point Protocol (PPP).
1605 .I PPP in HDLC-like Framing.
1610 .I IP Version 6 over PPP
1613 The following signals have the specified effect when sent to pppd.
1616 These signals cause pppd to terminate the link (by closing LCP),
1617 restore the serial device settings, and exit.
1620 This signal causes pppd to terminate the link, restore the serial
1621 device settings, and close the serial device. If the \fIpersist\fR or
1622 \fIdemand\fR option has been specified, pppd will try to reopen the
1623 serial device and start another connection (after the holdoff period).
1624 Otherwise pppd will exit. If this signal is received during the
1625 holdoff period, it causes pppd to end the holdoff period immediately.
1628 This signal toggles the state of the \fIdebug\fR option.
1631 This signal causes pppd to renegotiate compression. This can be
1632 useful to re-enable compression after it has been disabled as a result
1633 of a fatal decompression error. (Fatal decompression errors generally
1634 indicate a bug in one or other implementation.)
1637 Paul Mackerras (Paul.Mackerras@cs.anu.edu.au), based on earlier work by
projects / ppp.git / blob