1 .\" manual page [] for pppd 2.4
2 .\" $Id: pppd.8,v 1.66 2002/10/10 05:47:34 fcusack 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 or Linux, 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).
203 .B allow-number \fInumber
204 Allow peers to connect from the given telephone number. A trailing
205 `*' character will match all numbers beginning with the leading part.
208 Request that the peer compress packets that it sends, using the
209 BSD-Compress scheme, with a maximum code size of \fInr\fR bits, and
210 agree to compress packets sent to the peer with a maximum code size of
211 \fInt\fR bits. If \fInt\fR is not specified, it defaults to the value
212 given for \fInr\fR. Values in the range 9 to 15 may be used for
213 \fInr\fR and \fInt\fR; larger values give better compression but
214 consume more kernel memory for compression dictionaries.
215 Alternatively, a value of 0 for \fInr\fR or \fInt\fR disables
216 compression in the corresponding direction. Use \fInobsdcomp\fR or
217 \fIbsdcomp 0\fR to disable BSD-Compress compression entirely.
220 Use a non-standard hardware flow control (i.e. DTR/CTS) to control
221 the flow of data on the serial port. If neither the \fIcrtscts\fR,
222 the \fInocrtscts\fR, the \fIcdtrcts\fR nor the \fInocdtrcts\fR
223 option is given, the hardware flow control setting for the serial
224 port is left unchanged.
225 Some serial ports (such as Macintosh serial ports) lack a true
226 RTS output. Such serial ports use this mode to implement true
227 bi-directional flow control. The sacrifice is that this flow
228 control mode does not permit using DTR as a modem control line.
230 .B chap-interval \fIn
231 If this option is given, pppd will rechallenge the peer every \fIn\fR
234 .B chap-max-challenge \fIn
235 Set the maximum number of CHAP challenge transmissions to \fIn\fR
239 Set the CHAP restart interval (retransmission timeout for challenges)
240 to \fIn\fR seconds (default 3).
242 .B connect-delay \fIn
243 Wait for up \fIn\fR milliseconds after the connect script finishes for
244 a valid PPP packet from the peer. At the end of this time, or when a
245 valid PPP packet is received from the peer, pppd will commence
246 negotiation by sending its first LCP packet. The default value is
247 1000 (1 second). This wait period only applies if the \fBconnect\fR
248 or \fBpty\fR option is used.
251 Enables connection debugging facilities.
252 If this option is given, pppd will log the contents of all
253 control packets sent or received in a readable form. The packets are
254 logged through syslog with facility \fIdaemon\fR and level
255 \fIdebug\fR. This information can be directed to a file by setting up
256 /etc/syslog.conf appropriately (see syslog.conf(5)).
259 Disable asyncmap negotiation, forcing all control characters to be
260 escaped for both the transmit and the receive direction.
263 Disable MRU [Maximum Receive Unit] negotiation. With this option,
264 pppd will use the default MRU value of 1500 bytes for both the
265 transmit and receive direction.
268 Request that the peer compress packets that it sends, using the
269 Deflate scheme, with a maximum window size of \fI2**nr\fR bytes, and
270 agree to compress packets sent to the peer with a maximum window size
271 of \fI2**nt\fR bytes. If \fInt\fR is not specified, it defaults to
272 the value given for \fInr\fR. Values in the range 9 to 15 may be used
273 for \fInr\fR and \fInt\fR; larger values give better compression but
274 consume more kernel memory for compression dictionaries.
275 Alternatively, a value of 0 for \fInr\fR or \fInt\fR disables
276 compression in the corresponding direction. Use \fInodeflate\fR or
277 \fIdeflate 0\fR to disable Deflate compression entirely. (Note: pppd
278 requests Deflate compression in preference to BSD-Compress if the peer
282 Initiate the link only on demand, i.e. when data traffic is present.
283 With this option, the remote IP address must be specified by the user
284 on the command line or in an options file. Pppd will initially
285 configure the interface and enable it for IP traffic without
286 connecting to the peer. When traffic is available, pppd will
287 connect to the peer and perform negotiation, authentication, etc.
288 When this is completed, pppd will commence passing data packets
289 (i.e., IP packets) across the link.
291 The \fIdemand\fR option implies the \fIpersist\fR option. If this
292 behaviour is not desired, use the \fInopersist\fR option after the
293 \fIdemand\fR option. The \fIidle\fR and \fIholdoff\fR
294 options are also useful in conjuction with the \fIdemand\fR option.
297 Append the domain name \fId\fR to the local host name for authentication
298 purposes. For example, if gethostname() returns the name porsche, but
299 the fully qualified domain name is porsche.Quotron.COM, you could
300 specify \fIdomain Quotron.COM\fR. Pppd would then use the name
301 \fIporsche.Quotron.COM\fR for looking up secrets in the secrets file,
302 and as the default name to send to the peer when authenticating itself
303 to the peer. This option is privileged.
306 With the \fBdryrun\fR option, pppd will print out all the option
307 values which have been set and then exit, after parsing the command
308 line and options files and checking the option values, but before
309 initiating the link. The option values are logged at level info, and
310 also printed to standard output unless the device on standard output
311 is the device that pppd would be using to communicate with the peer.
314 With the \fBdump\fR option, pppd will print out all the option values
315 which have been set. This option is like the \fBdryrun\fR option
316 except that pppd proceeds as normal rather than exiting.
318 .B endpoint \fI<epdisc>
319 Sets the endpoint discriminator sent by the local machine to the peer
320 during multilink negotiation to \fI<epdisc>\fR. The default is to use
321 the MAC address of the first ethernet interface on the system, if any,
322 otherwise the IPv4 address corresponding to the hostname, if any,
323 provided it is not in the multicast or locally-assigned IP address
324 ranges, or the localhost address. The endpoint discriminator can be
325 the string \fBnull\fR or of the form \fItype\fR:\fIvalue\fR, where
326 type is a decimal number or one of the strings \fBlocal\fR, \fBIP\fR,
327 \fBMAC\fR, \fBmagic\fR, or \fBphone\fR. The value is an IP address in
328 dotted-decimal notation for the \fBIP\fR type, or a string of bytes in
329 hexadecimal, separated by periods or colons for the other types. For
330 the MAC type, the value may also be the name of an ethernet or similar
331 network interface. This option is currently only available under
335 When logging the contents of PAP packets, this option causes pppd to
336 exclude the password string from the log. This is the default.
339 Specifies how many seconds to wait before re-initiating the link after
340 it terminates. This option only has any effect if the \fIpersist\fR
341 or \fIdemand\fR option is used. The holdoff period is not applied if
342 the link was terminated because it was idle.
345 Specifies that pppd should disconnect if the link is idle for \fIn\fR
346 seconds. The link is idle when no data packets (i.e. IP packets) are
347 being sent or received. Note: it is not advisable to use this option
348 with the \fIpersist\fR option without the \fIdemand\fR option.
349 If the \fBactive-filter\fR
350 option is given, data packets which are rejected by the specified
351 activity filter also count as the link being idle.
354 With this option, pppd will accept the peer's idea of our local IP
355 address, even if the local IP address was specified in an option.
357 .B ipcp-accept-remote
358 With this option, pppd will accept the peer's idea of its (remote) IP
359 address, even if the remote IP address was specified in an option.
361 .B ipcp-max-configure \fIn
362 Set the maximum number of IPCP configure-request transmissions to
363 \fIn\fR (default 10).
365 .B ipcp-max-failure \fIn
366 Set the maximum number of IPCP configure-NAKs returned before starting
367 to send configure-Rejects instead to \fIn\fR (default 10).
369 .B ipcp-max-terminate \fIn
370 Set the maximum number of IPCP terminate-request transmissions to
374 Set the IPCP restart interval (retransmission timeout) to \fIn\fR
378 Provides an extra parameter to the ip-up and ip-down scripts. If this
379 option is given, the \fIstring\fR supplied is given as the 6th
380 parameter to those scripts.
382 .B ipv6cp-max-configure \fIn
383 Set the maximum number of IPv6CP configure-request transmissions to
384 \fIn\fR (default 10).
386 .B ipv6cp-max-failure \fIn
387 Set the maximum number of IPv6CP configure-NAKs returned before starting
388 to send configure-Rejects instead to \fIn\fR (default 10).
390 .B ipv6cp-max-terminate \fIn
391 Set the maximum number of IPv6CP terminate-request transmissions to
394 .B ipv6cp-restart \fIn
395 Set the IPv6CP restart interval (retransmission timeout) to \fIn\fR
399 Enable the IPXCP and IPX protocols. This option is presently only
400 supported under Linux, and only if your kernel has been configured to
404 Set the IPX network number in the IPXCP configure request frame to
405 \fIn\fR, a hexadecimal number (without a leading 0x). There is no
406 valid default. If this option is not specified, the network number is
407 obtained from the peer. If the peer does not have the network number,
408 the IPX protocol will not be started.
410 .B ipx-node \fIn\fB:\fIm
411 Set the IPX node numbers. The two node numbers are separated from each
412 other with a colon character. The first number \fIn\fR is the local
413 node number. The second number \fIm\fR is the peer's node number. Each
414 node number is a hexadecimal number, at most 10 digits long. The node
415 numbers on the ipx-network must be unique. There is no valid
416 default. If this option is not specified then the node numbers are
417 obtained from the peer.
419 .B ipx-router-name \fI<string>
420 Set the name of the router. This is a string and is sent to the peer
424 Set the routing protocol to be received by this option. More than one
425 instance of \fIipx-routing\fR may be specified. The '\fInone\fR'
426 option (0) may be specified as the only instance of ipx-routing. The
427 values may be \fI0\fR for \fINONE\fR, \fI2\fR for \fIRIP/SAP\fR, and
428 \fI4\fR for \fINLSP\fR.
430 .B ipxcp-accept-local
431 Accept the peer's NAK for the node number specified in the ipx-node
432 option. If a node number was specified, and non-zero, the default is
433 to insist that the value be used. If you include this option then you
434 will permit the peer to override the entry of the node number.
436 .B ipxcp-accept-network
437 Accept the peer's NAK for the network number specified in the
438 ipx-network option. If a network number was specified, and non-zero, the
439 default is to insist that the value be used. If you include this
440 option then you will permit the peer to override the entry of the node
443 .B ipxcp-accept-remote
444 Use the peer's network number specified in the configure request
445 frame. If a node number was specified for the peer and this option was
446 not specified, the peer will be forced to use the value which you have
449 .B ipxcp-max-configure \fIn
450 Set the maximum number of IPXCP configure request frames which the
451 system will send to \fIn\fR. The default is 10.
453 .B ipxcp-max-failure \fIn
454 Set the maximum number of IPXCP NAK frames which the local system will
455 send before it rejects the options. The default value is 3.
457 .B ipxcp-max-terminate \fIn
458 Set the maximum nuber of IPXCP terminate request frames before the
459 local system considers that the peer is not listening to them. The
463 Enable debugging code in the kernel-level PPP driver. The argument
464 values depend on the specific kernel driver, but in general a value of
465 1 will enable general kernel debug messages. (Note that these
466 messages are usually only useful for debugging the kernel driver
467 itself.) For the Linux 2.2.x kernel driver, the value is a sum of
469 enable general debug messages, 2 to request that the contents of
470 received packets be printed, and 4 to request that the contents of
471 transmitted packets be printed. On most systems, messages printed by
472 the kernel are logged by syslog(1) to a file as directed in the
473 /etc/syslog.conf configuration file.
476 Enables pppd to alter kernel settings as appropriate. Under Linux,
477 pppd will enable IP forwarding (i.e. set /proc/sys/net/ipv4/ip_forward
478 to 1) if the \fIproxyarp\fR option is used, and will enable the
479 dynamic IP address option (i.e. set /proc/sys/net/ipv4/ip_dynaddr to
480 1) in demand mode if the local address changes.
482 .B lcp-echo-failure \fIn
483 If this option is given, pppd will presume the peer to be dead
484 if \fIn\fR LCP echo-requests are sent without receiving a valid LCP
485 echo-reply. If this happens, pppd will terminate the
486 connection. Use of this option requires a non-zero value for the
487 \fIlcp-echo-interval\fR parameter. This option can be used to enable
488 pppd to terminate after the physical connection has been broken
489 (e.g., the modem has hung up) in situations where no hardware modem
490 control lines are available.
492 .B lcp-echo-interval \fIn
493 If this option is given, pppd will send an LCP echo-request frame to
494 the peer every \fIn\fR seconds. Normally the peer should respond to
495 the echo-request by sending an echo-reply. This option can be used
496 with the \fIlcp-echo-failure\fR option to detect that the peer is no
499 .B lcp-max-configure \fIn
500 Set the maximum number of LCP configure-request transmissions to
501 \fIn\fR (default 10).
503 .B lcp-max-failure \fIn
504 Set the maximum number of LCP configure-NAKs returned before starting
505 to send configure-Rejects instead to \fIn\fR (default 10).
507 .B lcp-max-terminate \fIn
508 Set the maximum number of LCP terminate-request transmissions to
512 Set the LCP restart interval (retransmission timeout) to \fIn\fR
515 .B linkname \fIname\fR
516 Sets the logical name of the link to \fIname\fR. Pppd will create a
517 file named \fBppp-\fIname\fB.pid\fR in /var/run (or /etc/ppp on some
518 systems) containing its process ID. This can be useful in determining
519 which instance of pppd is responsible for the link to a given peer
520 system. This is a privileged option.
523 Don't use the modem control lines. With this option, pppd will ignore
524 the state of the CD (Carrier Detect) signal from the modem and will
525 not change the state of the DTR (Data Terminal Ready) signal.
528 Send log messages to file descriptor \fIn\fR. Pppd will send log
529 messages to at most one file or file descriptor (as well as sending
530 the log messages to syslog), so this option and the \fBlogfile\fR
531 option are mutually exclusive. The default is for pppd to send log
532 messages to stdout (file descriptor 1), unless the serial port is
533 already open on stdout.
535 .B logfile \fIfilename
536 Append log messages to the file \fIfilename\fR (as well as sending the
537 log messages to syslog). The file is opened with the privileges of
538 the user who invoked pppd, in append mode.
541 Use the system password database for authenticating the peer using
542 PAP, and record the user in the system wtmp file. Note that the peer
543 must have an entry in the /etc/ppp/pap-secrets file as well as the
544 system password database to be allowed access.
547 Terminate the connection when it has been available for network
548 traffic for \fIn\fR seconds (i.e. \fIn\fR seconds after the first
549 network control protocol comes up).
552 Terminate after \fIn\fR consecutive failed connection attempts. A
553 value of 0 means no limit. The default value is 10.
556 Use the modem control lines. This option is the default. With this
557 option, pppd will wait for the CD (Carrier Detect) signal from the
558 modem to be asserted when opening the serial device (unless a connect
559 script is specified), and it will drop the DTR (Data Terminal Ready)
560 signal briefly when the connection is terminated and before executing
561 the connect script. On Ultrix, this option implies hardware flow
562 control, as for the \fIcrtscts\fR option.
565 Enables the use of PPP multilink; this is an alias for the `multilink'
566 option. This option is currently only available under Linux.
569 Allow MPPE to use stateful mode. Stateless mode is still attempted first.
570 The default is to disallow stateful mode.
573 Enables the use of short (12-bit) sequence numbers in multilink
574 headers, as opposed to 24-bit sequence numbers. This option is only
575 available under Linux, and only has any effect if multilink is
576 enabled (see the multilink option).
579 Sets the Maximum Reconstructed Receive Unit to \fIn\fR. The MRRU is
580 the maximum size for a received packet on a multilink bundle, and is
581 analogous to the MRU for the individual links. This option is
582 currently only available under Linux, and only has any effect if
583 multilink is enabled (see the multilink option).
586 If pppd is acting as a server for Microsoft Windows clients, this
587 option allows pppd to supply one or two DNS (Domain Name Server)
588 addresses to the clients. The first instance of this option specifies
589 the primary DNS address; the second instance (if given) specifies the
590 secondary DNS address. (This option was present in some older
591 versions of pppd under the name \fBdns-addr\fR.)
594 If pppd is acting as a server for Microsoft Windows or "Samba"
595 clients, this option allows pppd to supply one or two WINS (Windows
596 Internet Name Services) server addresses to the clients. The first
597 instance of this option specifies the primary WINS address; the second
598 instance (if given) specifies the secondary WINS address.
601 Enables the use of the PPP multilink protocol. If the peer also
602 supports multilink, then this link can become part of a bundle between
603 the local system and the peer. If there is an existing bundle to the
604 peer, pppd will join this link to that bundle, otherwise pppd will
605 create a new bundle. See the MULTILINK section below. This option is
606 currently only available under Linux.
609 Set the name of the local system for authentication purposes to
610 \fIname\fR. This is a privileged option. With this option, pppd will
611 use lines in the secrets files which have \fIname\fR as the second
612 field when looking for a secret to use in authenticating the peer. In
613 addition, unless overridden with the \fIuser\fR option, \fIname\fR
614 will be used as the name to send to the peer when authenticating the
615 local system to the peer. (Note that pppd does not append the domain
619 Set the interface netmask to \fIn\fR, a 32 bit netmask in "decimal dot"
620 notation (e.g. 255.255.255.0). If this option is given, the value
621 specified is ORed with the default netmask. The default netmask is
622 chosen based on the negotiated remote IP address; it is the
623 appropriate network mask for the class of the remote IP address, ORed
624 with the netmasks for any non point-to-point network interfaces in the
625 system which are on the same network. (Note: on some platforms, pppd
626 will always use 255.255.255.255 for the netmask, if that is the only
627 appropriate value for a point-to-point interface.)
630 Disable Address/Control compression in both directions (send and
634 Do not require the peer to authenticate itself. This option is
638 Disables BSD-Compress compression; \fBpppd\fR will not request or
639 agree to compress packets using the BSD-Compress scheme.
642 Disable CCP (Compression Control Protocol) negotiation. This option
643 should only be required if the peer is buggy and gets confused by
644 requests from pppd for CCP negotiation.
647 Disable hardware flow control (i.e. RTS/CTS) on the serial port.
648 If neither the \fIcrtscts\fR nor the \fInocrtscts\fR nor the
649 \fIcdtrcts\fR nor the \fInocdtrcts\fR option is given, the hardware
650 flow control setting for the serial port is left unchanged.
653 This option is a synonym for \fInocrtscts\fR. Either of these options will
654 disable both forms of hardware flow control.
657 Disable the \fIdefaultroute\fR option. The system administrator who
658 wishes to prevent users from creating default routes with pppd
659 can do so by placing this option in the /etc/ppp/options file.
662 Disables Deflate compression; pppd will not request or agree to
663 compress packets using the Deflate scheme.
666 Don't detach from the controlling terminal. Without this option, if a
667 serial device other than the terminal on the standard input is
668 specified, pppd will fork to become a background process.
671 Disables pppd from sending an endpoint discriminator to the peer or
672 accepting one from the peer (see the MULTILINK section below). This
673 option should only be required if the peer is buggy.
676 Disable IPCP negotiation and IP communication. This option should
677 only be required if the peer is buggy and gets confused by requests
678 from pppd for IPCP negotiation.
681 Disable IPv6CP negotiation and IPv6 communication. This option should
682 only be required if the peer is buggy and gets confused by requests
683 from pppd for IPv6CP negotiation.
686 Disables the default behaviour when no local IP address is specified,
687 which is to determine (if possible) the local IP address from the
688 hostname. With this option, the peer will have to supply the local IP
689 address during IPCP negotiation (unless it specified explicitly on the
690 command line or in an options file).
693 Disable the IPXCP and IPX protocols. This option should only be
694 required if the peer is buggy and gets confused by requests from pppd
695 for IPXCP negotiation.
698 Opposite of the \fIktune\fR option; disables pppd from changing system
702 Do not send log messages to a file or file descriptor. This option
703 cancels the \fBlogfd\fR and \fBlogfile\fR options.
706 Disable magic number negotiation. With this option, pppd cannot
707 detect a looped-back line. This option should only be needed if the
711 Disables the use of PPP multilink. This option is currently only
712 available under Linux.
715 Disables MPPE (Microsoft Point to Point Encryption). This is the default.
718 Disable 40\-bit encryption with MPPE.
721 Disable 128\-bit encryption with MPPE.
724 Disable MPPE stateful mode. This is the default.
727 Disables the use of short (12-bit) sequence numbers in the PPP
728 multilink protocol, forcing the use of 24-bit sequence numbers. This
729 option is currently only available under Linux, and only has any
730 effect if multilink is enabled.
733 Disables the use of PPP multilink. This option is currently only
734 available under Linux.
737 Disable protocol field compression negotiation in both the receive and
738 the transmit direction.
741 Exit once a connection has been made and terminated. This is the
742 default unless the \fIpersist\fR or \fIdemand\fR option has been
746 Do not accept or agree to Predictor-1 compression.
749 Disable the \fIproxyarp\fR option. The system administrator who
750 wishes to prevent users from creating proxy ARP entries with pppd can
751 do so by placing this option in the /etc/ppp/options file.
754 Normally, pppd requires a terminal device. With this option, pppd
755 will allocate itself a pseudo-tty master/slave pair and use the slave
756 as its terminal device. Pppd will create a child process to act as a
757 `character shunt' to transfer characters between the pseudo-tty master
758 and its standard input and output. Thus pppd will transmit characters
759 on its standard output and receive characters on its standard input
760 even if they are not terminal devices. This option increases the
761 latency and CPU overhead of transferring data over the ppp interface
762 as all of the characters sent and received must flow through the
763 character shunt process. An explicit device name may not be given if
767 Disable Van Jacobson style TCP/IP header compression in both the
768 transmit and the receive direction.
771 Disable the connection-ID compression option in Van Jacobson style
772 TCP/IP header compression. With this option, pppd will not omit the
773 connection-ID byte from Van Jacobson compressed TCP/IP headers, nor
774 ask the peer to do so.
777 Indicates that all secrets in the /etc/ppp/pap-secrets file which are
778 used for checking the identity of the peer are encrypted, and thus
779 pppd should not accept a password which, before encryption, is
780 identical to the secret from the /etc/ppp/pap-secrets file.
782 .B pap-max-authreq \fIn
783 Set the maximum number of PAP authenticate-request transmissions to
784 \fIn\fR (default 10).
787 Set the PAP restart interval (retransmission timeout) to \fIn\fR
791 Set the maximum time that pppd will wait for the peer to authenticate
792 itself with PAP to \fIn\fR seconds (0 means no limit).
794 .B pass-filter \fIfilter-expression
795 Specifies a packet filter to applied to data packets being sent or
796 received to determine which packets should be allowed to pass.
797 Packets which are rejected by the filter are silently discarded. This
798 option can be used to prevent specific network daemons (such as
799 routed) using up link bandwidth, or to provide a basic firewall
801 The \fIfilter-expression\fR syntax is as described for tcpdump(1),
802 except that qualifiers which are inappropriate for a PPP link, such as
803 \fBether\fR and \fBarp\fR, are not permitted. Generally the filter
804 expression should be enclosed in single-quotes to prevent whitespace
805 in the expression from being interpreted by the shell. Note that it
806 is possible to apply different constraints to incoming and outgoing
807 packets using the \fBinbound\fR and \fBoutbound\fR qualifiers. This
808 option is currently only available under NetBSD, and then only if both
809 the kernel and pppd were compiled with PPP_FILTER defined.
812 Do not exit after a connection is terminated; instead try to reopen
813 the connection. The \fBmaxfail\fR option still has an effect on
814 persistent connections.
816 .B plugin \fIfilename
817 Load the shared library object file \fIfilename\fR as a plugin. This
818 is a privileged option. If \fIfilename\fR does not contain a slash
819 (/), pppd will look in the \fB/usr/lib/pppd/\fIversion\fR directory
820 for the plugin, where
821 \fIversion\fR is the version number of pppd (for example, 2.4.2).
824 Request that the peer compress frames that it sends using Predictor-1
825 compression, and agree to compress transmitted frames with Predictor-1
826 if requested. This option has no effect unless the kernel driver
827 supports Predictor-1 compression.
829 .B privgroup \fIgroup-name
830 Allows members of group \fIgroup-name\fR to use privileged options.
831 This is a privileged option. Use of this option requires care as
832 there is no guarantee that members of \fIgroup-name\fR cannot use pppd
833 to become root themselves. Consider it equivalent to putting the
834 members of \fIgroup-name\fR in the kmem or disk group.
837 Add an entry to this system's ARP [Address Resolution Protocol] table
838 with the IP address of the peer and the Ethernet address of this
839 system. This will have the effect of making the peer appear to other
840 systems to be on the local ethernet.
843 Specifies that the command \fIscript\fR is to be used to communicate
844 rather than a specific terminal device. Pppd will allocate itself a
845 pseudo-tty master/slave pair and use the slave as its terminal
846 device. The \fIscript\fR will be run in a child process with the
847 pseudo-tty master as its standard input and output. An explicit
848 device name may not be given if this option is used. (Note: if the
849 \fIrecord\fR option is used in conjuction with the \fIpty\fR option,
850 the child process will have pipes on its standard input and output.)
853 With this option, pppd will accept all control characters from the
854 peer, including those marked in the receive asyncmap. Without this
855 option, pppd will discard those characters as specified in RFC1662.
856 This option should only be needed if the peer is buggy.
858 .B record \fIfilename
859 Specifies that pppd should record all characters sent and received to
860 a file named \fIfilename\fR. This file is opened in append mode,
861 using the user's user-ID and permissions. This option is implemented
862 using a pseudo-tty and a process to transfer characters between the
863 pseudo-tty and the real serial device, so it will increase the latency
864 and CPU overhead of transferring data over the ppp interface. The
865 characters are stored in a tagged format with timestamps, which can be
866 displayed in readable form using the pppdump(8) program.
868 .B remotename \fIname
869 Set the assumed name of the remote system for authentication purposes
872 .B remotenumber \fInumber
873 Set the assumed telephone number of the remote system for authentication
874 purposes to \fInumber\fR.
877 With this option, pppd will not agree to authenticate itself to the
881 With this option, pppd will not agree to authenticate itself to the
885 With this option, pppd will not agree to authenticate itself to the
886 peer using MS-CHAPv2.
889 With this option, pppd will not agree to authenticate itself to the
893 Require the peer to authenticate itself using CHAP [Challenge
894 Handshake Authentication Protocol] authentication.
897 Require the use of MPPE (Microsoft Point to Point Encryption). This
898 option disables all other compression types. This option enables
899 both 40\-bit and 128\-bit encryption. In order for MPPE to successfully
900 come up, you must have authenticated with either MS-CHAP or MS-CHAPv2.
901 This option is presently only supported under Linux, and only if your
902 kernel has been configured to include MPPE support.
905 Require the use of MPPE, with 40\-bit encryption.
908 Require the use of MPPE, with 128\-bit encryption.
911 Require the peer to authenticate itself using MS-CHAP [Microsft Challenge
912 Handshake Authentication Protocol] authentication.
915 Require the peer to authenticate itself using MS-CHAPv2 [Microsft Challenge
916 Handshake Authentication Protocol, Version 2] authentication.
919 Require the peer to authenticate itself using PAP [Password
920 Authentication Protocol] authentication.
923 When logging the contents of PAP packets, this option causes pppd to
924 show the password string in the log message.
927 With this option, pppd will not transmit LCP packets to initiate a
928 connection until a valid LCP packet is received from the peer (as for
929 the `passive' option with ancient versions of pppd).
932 Use synchronous HDLC serial encoding instead of asynchronous.
933 The device used by pppd with this option must have sync support.
934 Currently supports Microgate SyncLink adapters
935 under Linux and FreeBSD 2.2.8 and later.
938 With this option, pppd will detach from its controlling terminal once
939 it has successfully established the ppp connection (to the point where
940 the first network control protocol, usually the IP control protocol,
944 Enforce the use of the hostname (with domain name appended, if given)
945 as the name of the local system for authentication purposes (overrides
946 the \fIname\fR option). This option is not normally needed since the
947 \fIname\fR option is privileged.
950 Ask the peer for up to 2 DNS server addresses. The addresses supplied
951 by the peer (if any) are passed to the /etc/ppp/ip-up script in the
952 environment variables DNS1 and DNS2. In addition, pppd will create an
953 /etc/ppp/resolv.conf file containing one or two nameserver lines with
954 the address(es) supplied by the peer.
957 Sets the name used for authenticating the local system to the peer to
961 Sets the number of connection slots to be used by the Van Jacobson
962 TCP/IP header compression and decompression code to \fIn\fR, which
963 must be between 2 and 16 (inclusive).
966 Run the executable or shell command specified by \fIscript\fR before
967 initiating PPP negotiation, after the connect script (if any) has
968 completed. A value for this option from a privileged source cannot be
969 overridden by a non-privileged user.
972 Use software flow control (i.e. XON/XOFF) to control the flow of data on
975 Options can be taken from files as well as the command line. Pppd
976 reads options from the files /etc/ppp/options, ~/.ppprc and
977 /etc/ppp/options.\fIttyname\fR (in that order) before processing the
978 options on the command line. (In fact, the command-line options are
979 scanned to find the terminal name before the options.\fIttyname\fR
980 file is read.) In forming the name of the options.\fIttyname\fR file,
981 the initial /dev/ is removed from the terminal name, and any remaining
982 / characters are replaced with dots.
984 An options file is parsed into a series of words, delimited by
985 whitespace. Whitespace can be included in a word by enclosing the
986 word in double-quotes ("). A backslash (\\) quotes the following character.
987 A hash (#) starts a comment, which continues until the end of the
988 line. There is no restriction on using the \fIfile\fR or \fIcall\fR
989 options within an options file.
992 provides system administrators with sufficient access control that PPP
993 access to a server machine can be provided to legitimate users without
994 fear of compromising the security of the server or the network it's
995 on. This control is provided through restrictions on which IP
996 addresses the peer may use, based on its authenticated identity (if
997 any), and through restrictions on which options a non-privileged user
998 may use. Several of pppd's options are privileged, in particular
999 those which permit potentially insecure configurations; these options
1000 are only accepted in files which are under the control of the system
1001 administrator, or if pppd is being run by root.
1003 The default behaviour of pppd is to allow an unauthenticated peer to
1004 use a given IP address only if the system does not already have a
1005 route to that IP address. For example, a system with a
1006 permanent connection to the wider internet will normally have a
1007 default route, and thus all peers will have to authenticate themselves
1008 in order to set up a connection. On such a system, the \fIauth\fR
1009 option is the default. On the other hand, a system where the
1010 PPP link is the only connection to the internet will not normally have
1011 a default route, so the peer will be able to use almost any IP address
1012 without authenticating itself.
1014 As indicated above, some security-sensitive options are privileged,
1015 which means that they may not be used by an ordinary non-privileged
1016 user running a setuid-root pppd, either on the command line, in the
1017 user's ~/.ppprc file, or in an options file read using the \fIfile\fR
1018 option. Privileged options may be used in /etc/ppp/options file or in
1019 an options file read using the \fIcall\fR option. If pppd is being
1020 run by the root user, privileged options can be used without
1023 When opening the device, pppd uses either the invoking user's user ID
1024 or the root UID (that is, 0), depending on whether the device name was
1025 specified by the user or the system administrator. If the device name
1026 comes from a privileged source, that is, /etc/ppp/options or an
1027 options file read using the \fIcall\fR option, pppd uses full root
1028 privileges when opening the device. Thus, by creating an appropriate
1029 file under /etc/ppp/peers, the system administrator can allow users to
1030 establish a ppp connection via a device which they would not normally
1031 have permission to access. Otherwise pppd uses the invoking user's
1032 real UID when opening the device.
1034 Authentication is the process whereby one peer convinces the other of
1035 its identity. This involves the first peer sending its name to the
1036 other, together with some kind of secret information which could only
1037 come from the genuine authorized user of that name. In such an
1038 exchange, we will call the first peer the "client" and the other the
1039 "server". The client has a name by which it identifies itself to the
1040 server, and the server also has a name by which it identifies itself
1041 to the client. Generally the genuine client shares some secret (or
1042 password) with the server, and authenticates itself by proving that it
1043 knows that secret. Very often, the names used for authentication
1044 correspond to the internet hostnames of the peers, but this is not
1047 At present, pppd supports two authentication protocols: the Password
1048 Authentication Protocol (PAP) and the Challenge Handshake
1049 Authentication Protocol (CHAP). PAP involves the client sending its
1050 name and a cleartext password to the server to authenticate itself.
1051 In contrast, the server initiates the CHAP authentication exchange by
1052 sending a challenge to the client (the challenge packet includes the
1053 server's name). The client must respond with a response which
1054 includes its name plus a hash value derived from the shared secret and
1055 the challenge, in order to prove that it knows the secret.
1057 The PPP protocol, being symmetrical, allows both peers to require the
1058 other to authenticate itself. In that case, two separate and
1059 independent authentication exchanges will occur. The two exchanges
1060 could use different authentication protocols, and in principle,
1061 different names could be used in the two exchanges.
1063 The default behaviour of pppd is to agree to authenticate if
1064 requested, and to not require authentication from the peer. However,
1065 pppd will not agree to authenticate itself with a particular protocol
1066 if it has no secrets which could be used to do so.
1068 Pppd stores secrets for use in authentication in secrets
1069 files (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for
1070 CHAP/MS-CHAP/MS-CHAPv2).
1071 Both secrets files have the same format. The secrets files can
1072 contain secrets for pppd to use in authenticating itself to other
1073 systems, as well as secrets for pppd to use when authenticating other
1076 Each line in a secrets file contains one secret. A given secret is
1077 specific to a particular combination of client and server - it can
1078 only be used by that client to authenticate itself to that server.
1079 Thus each line in a secrets file has at least 3 fields: the name of
1080 the client, the name of the server, and the secret. These fields may
1081 be followed by a list of the IP addresses that the specified client
1082 may use when connecting to the specified server.
1084 A secrets file is parsed into words as for a options file, so the
1085 client name, server name and secrets fields must each be one word,
1086 with any embedded spaces or other special characters quoted or
1087 escaped. Note that case is significant in the client and server names
1090 If the secret starts with an `@', what follows is assumed to be the
1091 name of a file from which to read the secret. A "*" as the client or
1092 server name matches any name. When selecting a secret, pppd takes the
1093 best match, i.e. the match with the fewest wildcards.
1095 Any following words on the same line are taken to be a list of
1096 acceptable IP addresses for that client. If there are only 3 words on
1097 the line, or if the first word is "-", then all IP addresses are
1098 disallowed. To allow any address, use "*". A word starting with "!"
1099 indicates that the specified address is \fInot\fR acceptable. An
1100 address may be followed by "/" and a number \fIn\fR, to indicate a
1101 whole subnet, i.e. all addresses which have the same value in the most
1102 significant \fIn\fR bits. In this form, the address may be followed
1103 by a plus sign ("+") to indicate that one address from the subnet is
1104 authorized, based on the ppp network interface unit number in use.
1105 In this case, the host part of the address will be set to the unit
1108 Thus a secrets file contains both secrets for use in authenticating
1109 other hosts, plus secrets which we use for authenticating ourselves to
1110 others. When pppd is authenticating the peer (checking the peer's
1111 identity), it chooses a secret with the peer's name in the first
1112 field and the name of the local system in the second field. The
1113 name of the local system defaults to the hostname, with the domain
1114 name appended if the \fIdomain\fR option is used. This default can be
1115 overridden with the \fIname\fR option, except when the
1116 \fIusehostname\fR option is used.
1118 When pppd is choosing a secret to use in authenticating itself to the
1119 peer, it first determines what name it is going to use to identify
1120 itself to the peer. This name can be specified by the user with the
1121 \fIuser\fR option. If this option is not used, the name defaults to
1122 the name of the local system, determined as described in the previous
1123 paragraph. Then pppd looks for a secret with this name in the first
1124 field and the peer's name in the second field. Pppd will know the
1125 name of the peer if CHAP authentication is being used, because the
1126 peer will have sent it in the challenge packet. However, if PAP is being
1127 used, pppd will have to determine the peer's name from the options
1128 specified by the user. The user can specify the peer's name directly
1129 with the \fIremotename\fR option. Otherwise, if the remote IP address
1130 was specified by a name (rather than in numeric form), that name will
1131 be used as the peer's name. Failing that, pppd will use the null
1132 string as the peer's name.
1134 When authenticating the peer with PAP, the supplied password is first
1135 compared with the secret from the secrets file. If the password
1136 doesn't match the secret, the password is encrypted using crypt() and
1137 checked against the secret again. Thus secrets for authenticating the
1138 peer can be stored in encrypted form if desired. If the
1139 \fIpapcrypt\fR option is given, the first (unencrypted) comparison is
1140 omitted, for better security.
1142 Furthermore, if the \fIlogin\fR option was specified, the username and
1143 password are also checked against the system password database. Thus,
1144 the system administrator can set up the pap-secrets file to allow PPP
1145 access only to certain users, and to restrict the set of IP addresses
1146 that each user can use. Typically, when using the \fIlogin\fR option,
1147 the secret in /etc/ppp/pap-secrets would be "", which will match any
1148 password supplied by the peer. This avoids the need to have the same
1149 secret in two places.
1151 Authentication must be satisfactorily completed before IPCP (or any
1152 other Network Control Protocol) can be started. If the peer is
1153 required to authenticate itself, and fails to do so, pppd will
1154 terminated the link (by closing LCP). If IPCP negotiates an
1155 unacceptable IP address for the remote host, IPCP will be closed. IP
1156 packets can only be sent or received when IPCP is open.
1158 In some cases it is desirable to allow some hosts which can't
1159 authenticate themselves to connect and use one of a restricted set of
1160 IP addresses, even when the local host generally requires
1161 authentication. If the peer refuses to authenticate itself when
1162 requested, pppd takes that as equivalent to authenticating with PAP
1163 using the empty string for the username and password. Thus, by adding
1164 a line to the pap-secrets file which specifies the empty string for
1165 the client and password, it is possible to allow restricted access to
1166 hosts which refuse to authenticate themselves.
1169 When IPCP negotiation is completed successfully, pppd will inform the
1170 kernel of the local and remote IP addresses for the ppp interface.
1171 This is sufficient to create a host route to the remote end of the
1172 link, which will enable the peers to exchange IP packets.
1173 Communication with other machines generally requires further
1174 modification to routing tables and/or ARP (Address Resolution
1175 Protocol) tables. In most cases the \fIdefaultroute\fR and/or
1176 \fIproxyarp\fR options are sufficient for this, but in some cases
1177 further intervention is required. The /etc/ppp/ip-up script can be
1180 Sometimes it is desirable to add a default route through the remote
1181 host, as in the case of a machine whose only connection to the
1182 Internet is through the ppp interface. The \fIdefaultroute\fR option
1183 causes pppd to create such a default route when IPCP comes up, and
1184 delete it when the link is terminated.
1186 In some cases it is desirable to use proxy ARP, for example on a
1187 server machine connected to a LAN, in order to allow other hosts to
1188 communicate with the remote host. The \fIproxyarp\fR option causes
1189 pppd to look for a network interface on the same subnet as the remote
1190 host (an interface supporting broadcast and ARP, which is up and not a
1191 point-to-point or loopback interface). If found, pppd creates a
1192 permanent, published ARP entry with the IP address of the remote host
1193 and the hardware address of the network interface found.
1195 When the \fIdemand\fR option is used, the interface IP addresses have
1196 already been set at the point when IPCP comes up. If pppd has not
1197 been able to negotiate the same addresses that it used to configure
1198 the interface (for example when the peer is an ISP that uses dynamic
1199 IP address assignment), pppd has to change the interface IP addresses
1200 to the negotiated addresses. This may disrupt existing connections,
1201 and the use of demand dialling with peers that do dynamic IP address
1202 assignment is not recommended.
1204 Multilink PPP provides the capability to combine two or more PPP links
1205 between a pair of machines into a single `bundle', which appears as a
1206 single virtual PPP link which has the combined bandwidth of the
1207 individual links. Currently, multilink PPP is only supported under
1210 Pppd detects that the link it is controlling is connected to the same
1211 peer as another link using the peer's endpoint discriminator and the
1212 authenticated identity of the peer (if it authenticates itself). The
1213 endpoint discriminator is a block of data which is hopefully unique
1214 for each peer. Several types of data can be used, including
1215 locally-assigned strings of bytes, IP addresses, MAC addresses,
1216 randomly strings of bytes, or E-164 phone numbers. The endpoint
1217 discriminator sent to the peer by pppd can be set using the endpoint
1220 In circumstances the peer may send no endpoint discriminator or a
1221 non-unique value. The optional bundle option adds an extra string
1222 which is added to the peer's endpoint discriminator and authenticated
1223 identity when matching up links to be joined together in a bundle.
1224 The bundle option can also be used to allow the establishment of
1225 multiple bundles between the local system and the peer. Pppd uses a
1226 TDB database in /var/run/pppd.tdb to match up links.
1228 Assuming that multilink is enabled and the peer is willing to
1229 negotiate multilink, then when pppd is invoked to bring up the first
1230 link to the peer, it will detect that no other link is connected to
1231 the peer and create a new bundle, that is, another ppp network
1232 interface unit. When another pppd is invoked to bring up another link
1233 to the peer, it will detect the existing bundle and join its link to
1234 it. Currently, if the first pppd terminates (for example, because of
1235 a hangup or a received signal) the bundle is destroyed.
1238 The following examples assume that the /etc/ppp/options file contains
1239 the \fIauth\fR option (as in the default /etc/ppp/options file in the
1242 Probably the most common use of pppd is to dial out to an ISP. This
1243 can be done with a command such as
1247 where the /etc/ppp/peers/isp file is set up by the system
1248 administrator to contain something like this:
1252 connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
1256 In this example, we are using chat to dial the ISP's modem and go
1257 through any logon sequence required. The /etc/ppp/chat-isp file
1258 contains the script used by chat; it could for example contain
1259 something like this:
1271 ABORT "Username/Password Incorrect"
1279 "name:" "^Umyuserid"
1281 "word:" "\\qmypassword"
1287 See the chat(8) man page for details of chat scripts.
1289 Pppd can also be used to provide a dial-in ppp service for users. If
1290 the users already have login accounts, the simplest way to set up the
1291 ppp service is to let the users log in to their accounts and run pppd
1292 (installed setuid-root) with a command such as
1296 To allow a user to use the PPP facilities, you need to allocate an IP
1297 address for that user's machine and create an entry in
1298 /etc/ppp/pap-secrets or /etc/ppp/chap-secrets (depending on which
1299 authentication method the PPP implementation on the user's machine
1300 supports), so that the user's
1301 machine can authenticate itself. For example, if Joe has a machine
1302 called "joespc" which is to be allowed to dial in to the machine
1303 called "server" and use the IP address joespc.my.net, you would add an
1304 entry like this to /etc/ppp/pap-secrets or /etc/ppp/chap-secrets:
1306 joespc server "joe's secret" joespc.my.net
1308 Alternatively, you can create a username called (for example) "ppp",
1309 whose login shell is pppd and whose home directory is /etc/ppp.
1310 Options to be used when pppd is run this way can be put in
1313 If your serial connection is any more complicated than a piece of
1314 wire, you may need to arrange for some control characters to be
1315 escaped. In particular, it is often useful to escape XON (^Q) and
1316 XOFF (^S), using \fIasyncmap a0000\fR. If the path includes a telnet,
1317 you probably should escape ^] as well (\fIasyncmap 200a0000\fR). If
1318 the path includes an rlogin, you will need to use the \fIescape ff\fR
1319 option on the end which is running the rlogin client, since many
1320 rlogin implementations are not transparent; they will remove the
1321 sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the
1325 Messages are sent to the syslog daemon using facility LOG_DAEMON.
1326 (This can be overriden by recompiling pppd with the macro
1327 LOG_PPP defined as the desired facility.) In order to see the error
1328 and debug messages, you will need to edit your /etc/syslog.conf file
1329 to direct the messages to the desired output device or file.
1331 The \fIdebug\fR option causes the contents of all control packets sent
1332 or received to be logged, that is, all LCP, PAP, CHAP or IPCP packets.
1333 This can be useful if the PPP negotiation does not succeed or if
1334 authentication fails.
1335 If debugging is enabled at compile time, the \fIdebug\fR option also
1336 causes other debugging messages to be logged.
1338 Debugging can also be enabled or disabled by sending a SIGUSR1 signal
1339 to the pppd process. This signal acts as a toggle.
1341 The exit status of pppd is set to indicate whether any error was
1342 detected, or the reason for the link being terminated. The values
1346 Pppd has detached, or otherwise the connection was successfully
1347 established and terminated at the peer's request.
1350 An immediately fatal error of some kind occurred, such as an essential
1351 system call failing, or running out of virtual memory.
1354 An error was detected in processing the options given, such as two
1355 mutually exclusive options being used.
1358 Pppd is not setuid-root and the invoking user is not root.
1361 The kernel does not support PPP, for example, the PPP kernel driver is
1362 not included or cannot be loaded.
1365 Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP
1369 The serial port could not be locked.
1372 The serial port could not be opened.
1375 The connect script failed (returned a non-zero exit status).
1378 The command specified as the argument to the \fIpty\fR option could
1382 The PPP negotiation failed, that is, it didn't reach the point where
1383 at least one network protocol (e.g. IP) was running.
1386 The peer system failed (or refused) to authenticate itself.
1389 The link was established successfully and terminated because it was
1393 The link was established successfully and terminated because the
1394 connect time limit was reached.
1397 Callback was negotiated and an incoming call should arrive shortly.
1400 The link was terminated because the peer is not responding to echo
1404 The link was terminated by the modem hanging up.
1407 The PPP negotiation failed because serial loopback was detected.
1410 The init script failed (returned a non-zero exit status).
1413 We failed to authenticate ourselves to the peer.
1415 Pppd invokes scripts at various stages in its processing which can be
1416 used to perform site-specific ancillary processing. These scripts are
1417 usually shell scripts, but could be executable code files instead.
1418 Pppd does not wait for the scripts to finish. The scripts are
1419 executed as root (with the real and effective user-id set to 0), so
1420 that they can do things such as update routing tables or run
1421 privileged daemons. Be careful that the contents of these scripts do
1422 not compromise your system's security. Pppd runs the scripts with
1423 standard input, output and error redirected to /dev/null, and with an
1424 environment that is empty except for some environment variables that
1425 give information about the link. The environment variables that pppd
1429 The name of the serial tty device being used.
1432 The name of the network interface being used.
1435 The IP address for the local end of the link. This is only set when
1439 The IP address for the remote end of the link. This is only set when
1443 The authenticated name of the peer. This is only set if the peer
1444 authenticates itself.
1447 The baud rate of the tty device.
1450 The real user-id of the user who invoked pppd.
1453 The username of the real user-id that invoked pppd. This is always set.
1455 For the ip-down and auth-down scripts, pppd also sets the following
1456 variables giving statistics for the connection:
1459 The number of seconds from when the PPP negotiation started until the
1460 connection was terminated.
1463 The number of bytes sent (at the level of the serial port) during the
1467 The number of bytes received (at the level of the serial port) during
1471 The logical name of the link, set with the \fIlinkname\fR option.
1473 Pppd invokes the following scripts, if they exist. It is not an error
1474 if they don't exist.
1477 A program or script which is executed after the remote system
1478 successfully authenticates itself. It is executed with the parameters
1480 \fIinterface-name peer-name user-name tty-device speed\fR
1482 Note that this script is not executed if the peer doesn't authenticate
1483 itself, for example when the \fInoauth\fR option is used.
1485 .B /etc/ppp/auth-down
1486 A program or script which is executed when the link goes down, if
1487 /etc/ppp/auth-up was previously executed. It is executed in the same
1488 manner with the same parameters as /etc/ppp/auth-up.
1491 A program or script which is executed when the link is available for
1492 sending and receiving IP packets (that is, IPCP has come up). It is
1493 executed with the parameters
1495 \fIinterface-name tty-device speed local-IP-address
1496 remote-IP-address ipparam\fR
1499 A program or script which is executed when the link is no longer
1500 available for sending and receiving IP packets. This script can be
1501 used for undoing the effects of the /etc/ppp/ip-up script. It is
1502 invoked in the same manner and with the same parameters as the ip-up
1506 Like /etc/ppp/ip-up, except that it is executed when the link is available
1507 for sending and receiving IPv6 packets. It is executed with the parameters
1509 \fIinterface-name tty-device speed local-link-local-address
1510 remote-link-local-address ipparam\fR
1512 .B /etc/ppp/ipv6-down
1513 Similar to /etc/ppp/ip-down, but it is executed when IPv6 packets can no
1514 longer be transmitted on the link. It is executed with the same parameters
1515 as the ipv6-up script.
1518 A program or script which is executed when the link is available for
1519 sending and receiving IPX packets (that is, IPXCP has come up). It is
1520 executed with the parameters
1522 \fIinterface-name tty-device speed network-number local-IPX-node-address
1523 remote-IPX-node-address local-IPX-routing-protocol remote-IPX-routing-protocol
1524 local-IPX-router-name remote-IPX-router-name ipparam pppd-pid\fR
1526 The local-IPX-routing-protocol and remote-IPX-routing-protocol field
1527 may be one of the following:
1529 NONE to indicate that there is no routing protocol
1531 RIP to indicate that RIP/SAP should be used
1533 NLSP to indicate that Novell NLSP should be used
1535 RIP NLSP to indicate that both RIP/SAP and NLSP should be used
1537 .B /etc/ppp/ipx-down
1538 A program or script which is executed when the link is no longer
1539 available for sending and receiving IPX packets. This script can be
1540 used for undoing the effects of the /etc/ppp/ipx-up script. It is
1541 invoked in the same manner and with the same parameters as the ipx-up
1545 .B /var/run/ppp\fIn\fB.pid \fR(BSD or Linux), \fB/etc/ppp/ppp\fIn\fB.pid \fR(others)
1546 Process-ID for pppd process on ppp interface unit \fIn\fR.
1548 .B /var/run/ppp-\fIname\fB.pid \fR(BSD or Linux),
1549 \fB/etc/ppp/ppp-\fIname\fB.pid \fR(others)
1550 Process-ID for pppd process for logical link \fIname\fR (see the
1551 \fIlinkname\fR option).
1553 .B /etc/ppp/pap-secrets
1554 Usernames, passwords and IP addresses for PAP authentication. This
1555 file should be owned by root and not readable or writable by any other
1556 user. Pppd will log a warning if this is not the case.
1558 .B /etc/ppp/chap-secrets
1559 Names, secrets and IP addresses for CHAP/MS-CHAP/MS-CHAPv2 authentication.
1560 As for /etc/ppp/pap-secrets, this file should be owned by root and not
1561 readable or writable by any other user. Pppd will log a warning if
1562 this is not the case.
1565 System default options for pppd, read before user default options or
1566 command-line options.
1569 User default options, read before /etc/ppp/options.\fIttyname\fR.
1571 .B /etc/ppp/options.\fIttyname
1572 System default options for the serial port being used, read after
1573 ~/.ppprc. In forming the \fIttyname\fR part of this
1574 filename, an initial /dev/ is stripped from the port name (if
1575 present), and any slashes in the remaining part are converted to
1579 A directory containing options files which may contain privileged
1580 options, even if pppd was invoked by a user other than root. The
1581 system administrator can create options files in this directory to
1582 permit non-privileged users to dial out without requiring the peer to
1583 authenticate, but only to certain trusted peers.
1588 \fICompressing TCP/IP headers for low-speed serial links.\fR
1593 .I The MD5 Message-Digest Algorithm.
1598 .I PPP Internet Protocol Control Protocol (IPCP).
1602 Lloyd, B.; Simpson, W.A.
1603 .I PPP authentication protocols.
1608 .I The Point\-to\-Point Protocol (PPP).
1613 .I PPP in HDLC-like Framing.
1618 .I IP Version 6 over PPP
1621 The following signals have the specified effect when sent to pppd.
1624 These signals cause pppd to terminate the link (by closing LCP),
1625 restore the serial device settings, and exit.
1628 This signal causes pppd to terminate the link, restore the serial
1629 device settings, and close the serial device. If the \fIpersist\fR or
1630 \fIdemand\fR option has been specified, pppd will try to reopen the
1631 serial device and start another connection (after the holdoff period).
1632 Otherwise pppd will exit. If this signal is received during the
1633 holdoff period, it causes pppd to end the holdoff period immediately.
1636 This signal toggles the state of the \fIdebug\fR option.
1639 This signal causes pppd to renegotiate compression. This can be
1640 useful to re-enable compression after it has been disabled as a result
1641 of a fatal decompression error. (Fatal decompression errors generally
1642 indicate a bug in one or other implementation.)
1645 Paul Mackerras (Paul.Mackerras@cs.anu.edu.au), based on earlier work by
projects / ppp.git / blob