Manual Pages for UNIX Darwin command on man pppd

PPPD(8) PPPD(8)

NAME

pppd - Point-to-Point Protocol Daemon

SYNOPSIS

ppppppdd [ options ]

DESCRIPTION

PPP is the protocol used for establishing internet links over dial-up

modems, DSL connections, and many other types of point-to-point links.

The pppd daemon works together with the kernel PPP driver to establish

and maintain a PPP link with another system (called the peer) and to negotiate Internet Protocol (IP) addresses for each end of the link.

Pppd can also authenticate the peer and/or supply authentication infor-

mation to the peer. PPP can be used with other network protocols besides IP, but such use is becoming increasingly rare. FFRREEQQUUEENNTTLLYY UUSSEEDD OOPPTTIIOONNSS ttyname Use the serial port called ttyname to communicate with the peer. The string "/dev/" is prepended to ttyname to form the name of the device to open. If no device name is given, or if the name

of the terminal connected to the standard input is given, pppd

will use that terminal, and will not fork to put itself in the background. A value for this option from a privileged source

cannot be overridden by a non-privileged user.

speed An option that is a decimal number is taken as the desired baud rate for the serial device. On systems such as 4.4BSD and NetBSD, any speed can be specified. Other systems (e.g. Linux,

SunOS) only support the commonly-used baud rates.

aassyynnccmmaapp map

This option sets the Async-Control-Character-Map (ACCM) for this

end of the link. The ACCM is a set of 32 bits, one for each of the ASCII control characters with values from 0 to 31, where a 1 bit indicates that the corresponding control character should not be used in PPP packets sent to this system. The map is encoded as a hexadecimal number (without a leading 0x) where the least significant bit (00000001) represents character 0 and the most significant bit (80000000) represents character 31. Pppd

will ask the peer to send these characters as a 2-byte escape

sequence. If multiple asyncmap options are given, the values are ORed together. If no asyncmap option is given, the default

is zero, so pppd will ask the peer not to escape any control

characters. To escape transmitted characters, use the escape option. aauutthh Require the peer to authenticate itself before allowing network packets to be sent or received. This option is the default if the system has a default route. If neither this option nor the

noauth option is specified, pppd will only allow the peer to use

IP addresses to which the system does not already have a route. ccaallll name Read options from the file /etc/ppp/peers/name. This file may

contain privileged options, such as noauth, even if pppd is not

being run by root. The name string may not begin with / or include .. as a pathname component. The format of the options file is described below. ccoonnnneecctt script Usually there is something which needs to be done to prepare the link before the PPP protocol can be started; for instance, with

a dial-up modem, commands need to be sent to the modem to dial

the appropriate phone number. This option specifies an command

for pppd to execute (by passing it to a shell) before attempting

to start PPP negotiation. The chat (8) program is often useful here, as it provides a way to send arbitrary strings to a modem and respond to received characters. A value for this option

from a privileged source cannot be overridden by a non-privi-

leged user. ccrrttssccttss

Specifies that pppd should set the serial port to use hardware

flow control using the RTS and CTS signals in the RS-232 inter-

face. If neither the crtscts, the nocrtscts, the cdtrcts nor the nocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged. Some serial ports (such as Macintosh serial ports) lack a true RTS output. Such serial ports use this mode to implement unidirectional flow control. The serial port will suspend transmission when requested by the modem (via CTS) but will be unable to request the modem to stop sending to the computer. This mode retains the ability to use DTR as a modem control line. ddeeffaauullttrroouuttee Add a default route to the system routing tables, using the peer as the gateway, when IPCP negotiation is successfully completed. This entry is removed when the PPP connection is broken. This

option is privileged if the nodefaultroute option has been spec-

ified. ddiissccoonnnneecctt script Execute the command specified by script, by passing it to a

shell, after pppd has terminated the link. This command could,

for example, issue commands to the modem to cause it to hang up

if hardware modem control signals were not available. The dis-

connect script is not run if the modem has already hung up. A

value for this option from a privileged source cannot be over-

ridden by a non-privileged user.

eessccaappee xx,yy,...

Specifies that certain characters should be escaped on transmis-

sion (regardless of whether the peer requests them to be escaped with its async control character map). The characters to be

escaped are specified as a list of hex numbers separated by com-

mas. Note that almost any character can be specified for the

escape option, unlike the asyncmap option which only allows con-

trol characters to be specified. The characters which may not

be escaped are those with hex values 0x20 - 0x3f or 0x5e.

ffiillee name Read options from file name (the format is described below).

The file must be readable by the user who has invoked pppd.

iinniitt script Execute the command specified by script, by passing it to a

shell, to initialize the serial line. This script would typi-

cally use the chat(8) program to configure the modem to enable auto answer. A value for this option from a privileged source

cannot be overridden by a non-privileged user.

lloocckk Specifies that pppd should create a UUCP-style lock file for the

serial device to ensure exclusive access to the device. mmrruu n Set the MRU [Maximum Receive Unit] value to n. Pppd will ask the peer to send packets of no more than n bytes. The value of n must be between 128 and 16384; the default is 1500. A value of 296 works well on very slow links (40 bytes for TCP/IP header + 256 bytes of data). Note that for the IPv6 protocol, the MRU must be at least 1280. mmttuu n Set the MTU [Maximum Transmit Unit] value to n. Unless the peer

requests a smaller value via MRU negotiation, pppd will request

that the kernel networking code send data packets of no more than n bytes through the PPP network interface. Note that for the IPv6 protocol, the MTU must be at least 1280. ppaassssiivvee

Enables the "passive" option in the LCP. With this option, pppd

will attempt to initiate a connection; if no reply is received

from the peer, pppd will then just wait passively for a valid

LCP packet from the peer, instead of exiting, as it would with-

out this option. OOPPTTIIOONNSS :: Set the local and/or remote interface IP addresses. Either one may be omitted. The IP addresses can be specified with a host name or in decimal dot notation (e.g. 150.234.56.78). The default local address is the (first) IP address of the system (unless the noipdefault option is given). The remote address will be obtained from the peer if not specified in any option. Thus, in simple cases, this option is not required. If a local

and/or remote IP address is specified with this option, pppd

will not accept a different value from the peer in the IPCP

negotiation, unless the ipcp-accept-local and/or ipcp-accept-

remote options are given, respectively. iippvv66 ,

Set the local and/or remote 64-bit interface identifier. Either

one may be omitted. The identifier must be specified in standard ascii notation of IPv6 addresses (e.g. ::dead:beef). If the

ipv6cp-use-ipaddr option is given, the local identifier is the

local IPv4 address (see above). On systems which supports a

unique persistent id, such as EUI-48 derived from the Ethernet

MAC address, ipv6cp-use-persistent option can be used to replace

the ipv6 , option. Otherwise the identifier is randomized.

aaccttiivvee-ffiilltteerr filter-expression

Specifies a packet filter to be applied to data packets to determine which packets are to be regarded as link activity, and therefore reset the idle timer, or cause the link to be brought

up in demand-dialing mode. This option is useful in conjunction

with the iiddllee option if there are packets being sent or received

regularly over the link (for example, routing information pack-

ets) which would otherwise prevent the link from ever appearing

to be idle. The filter-expression syntax is as described for

tcpdump(1), except that qualifiers which are inappropriate for a PPP link, such as eetthheerr and aarrpp, are not permitted. Generally

the filter expression should be enclosed in single-quotes to

prevent whitespace in the expression from being interpreted by the shell. This option is currently only available under Linux,

and requires that the kernel was configured to include PPP fil-

tering support (CONFIGPPPFILTER). Note that it is possible to apply different constraints to incoming and outgoing packets using the iinnbboouunndd and oouuttbboouunndd qualifiers.

aallllooww-iipp address(es)

Allow peers to use the given IP address or subnet without authenticating themselves. The parameter is parsed as for each element of the list of allowed IP addresses in the secrets files (see the AUTHENTICATION section below).

aallllooww-nnuummbbeerr number

Allow peers to connect from the given telephone number. A trailing `*' character will match all numbers beginning with the leading part. bbssddccoommpp nr,nt Request that the peer compress packets that it sends, using the

BSD-Compress scheme, with a maximum code size of nr bits, and

agree to compress packets sent to the peer with a maximum code size of nt bits. If nt is not specified, it defaults to the value given for nr. Values in the range 9 to 15 may be used for nr and nt; larger values give better compression but consume more kernel memory for compression dictionaries. Alternatively,

a value of 0 for nr or nt disables compression in the corre-

sponding direction. Use nobsdcomp or bsdcomp 0 to disable BSD-

Compress compression entirely. ccddttrrccttss

Use a non-standard hardware flow control (i.e. DTR/CTS) to con-

trol the flow of data on the serial port. If neither the crtscts, the nocrtscts, the cdtrcts nor the nocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged. Some serial ports (such as Macintosh serial ports) lack a true RTS output. Such serial ports use this mode

to implement true bi-directional flow control. The sacrifice is

that this flow control mode does not permit using DTR as a modem control line.

cchhaapp-iinntteerrvvaall n

If this option is given, pppd will rechallenge the peer every n

seconds.

cchhaapp-mmaaxx-cchhaalllleennggee n

Set the maximum number of CHAP challenge transmissions to n (default 10).

cchhaapp-rreessttaarrtt n

Set the CHAP restart interval (retransmission timeout for chal-

lenges) to n seconds (default 3).

ccoonnnneecctt-ddeellaayy n

Wait for up n milliseconds after the connect script finishes for a valid PPP packet from the peer. At the end of this time, or

when a valid PPP packet is received from the peer, pppd will

commence negotiation by sending its first LCP packet. The default value is 1000 (1 second). This wait period only applies if the ccoonnnneecctt or ppttyy option is used. ddeebbuugg Enables connection debugging facilities. If this option is

given, pppd will log the contents of all control packets sent or

received in a readable form. The packets are logged through syslog with facility daemon and level debug. This information

can be directed to a file by setting up /etc/syslog.conf appro-

priately (see syslog.conf(5)).

ddeeffaauulltt-aassyynnccmmaapp

Disable asyncmap negotiation, forcing all control characters to be escaped for both the transmit and the receive direction.

ddeeffaauulltt-mmrruu

Disable MRU [Maximum Receive Unit] negotiation. With this

option, pppd will use the default MRU value of 1500 bytes for

both the transmit and receive direction. ddeeffllaattee nr,nt Request that the peer compress packets that it sends, using the Deflate scheme, with a maximum window size of 2**nr bytes, and agree to compress packets sent to the peer with a maximum window size of 2**nt bytes. If nt is not specified, it defaults to the value given for nr. Values in the range 9 to 15 may be used for nr and nt; larger values give better compression but consume more kernel memory for compression dictionaries. Alternatively,

a value of 0 for nr or nt disables compression in the corre-

sponding direction. Use nodeflate or deflate 0 to disable

Deflate compression entirely. (Note: pppd requests Deflate com-

pression in preference to BSD-Compress if the peer can do

either.) ddeemmaanndd Initiate the link only on demand, i.e. when data traffic is

present. With this option, the remote IP address must be speci-

fied by the user on the command line or in an options file. Pppd will initially configure the interface and enable it for IP

traffic without connecting to the peer. When traffic is avail-

able, pppd will connect to the peer and perform negotiation,

authentication, etc. When this is completed, pppd will commence

passing data packets (i.e., IP packets) across the link. The demand option implies the persist option. If this behaviour is not desired, use the nopersist option after the demand

option. The idle and holdoff options are also useful in conjuc-

tion with the demand option. ddoommaaiinn d

Append the domain name d to the local host name for authentica-

tion purposes. For example, if gethostname() returns the name porsche, but the fully qualified domain name is porsche.Quotron.COM, you could specify domain Quotron.COM. Pppd would then use the name porsche.Quotron.COM for looking up secrets in the secrets file, and as the default name to send to the peer when authenticating itself to the peer. This option is privileged.

ddrryyrruunn With the ddrryyrruunn option, pppd will print out all the option val-

ues which have been set and then exit, after parsing the command line and options files and checking the option values, but before initiating the link. The option values are logged at level info, and also printed to standard output unless the

device on standard output is the device that pppd would be using

to communicate with the peer.

dduummpp With the dduummpp option, pppd will print out all the option values

which have been set. This option is like the ddrryyrruunn option

except that pppd proceeds as normal rather than exiting.

eennddppooiinntt Sets the endpoint discriminator sent by the local machine to the peer during multilink negotiation to . The default is to use the MAC address of the first ethernet interface on the system, if any, otherwise the IPv4 address corresponding to the hostname, if any, provided it is not in the multicast or

locally-assigned IP address ranges, or the localhost address.

The endpoint discriminator can be the string nnuullll or of the form type:value, where type is a decimal number or one of the strings llooccaall, IIPP, MMAACC, mmaaggiicc, or pphhoonnee. The value is an IP address in

dotted-decimal notation for the IIPP type, or a string of bytes in

hexadecimal, separated by periods or colons for the other types. For the MAC type, the value may also be the name of an ethernet or similar network interface. This option is currently only available under Linux.

hhiiddee-ppaasssswwoorrdd

When logging the contents of PAP packets, this option causes

pppd to exclude the password string from the log. This is the

default. hhoollddooffff n

Specifies how many seconds to wait before re-initiating the link

after it terminates. This option only has any effect if the persist or demand option is used. The holdoff period is not applied if the link was terminated because it was idle.

iiddllee n Specifies that pppd should disconnect if the link is idle for n

seconds. The link is idle when no data packets (i.e. IP pack-

ets) are being sent or received. Note: it is not advisable to use this option with the persist option without the demand

option. If the aaccttiivvee-ffiilltteerr option is given, data packets

which are rejected by the specified activity filter also count as the link being idle.

iippccpp-aacccceepptt-llooccaall

With this option, pppd will accept the peer's idea of our local

IP address, even if the local IP address was specified in an option.

iippccpp-aacccceepptt-rreemmoottee

With this option, pppd will accept the peer's idea of its

(remote) IP address, even if the remote IP address was specified in an option.

iippccpp-mmaaxx-ccoonnffiigguurree n

Set the maximum number of IPCP configure-request transmissions

to n (default 10).

iippccpp-mmaaxx-ffaaiilluurree n

Set the maximum number of IPCP configure-NAKs returned before

starting to send configure-Rejects instead to n (default 10).

iippccpp-mmaaxx-tteerrmmiinnaattee n

Set the maximum number of IPCP terminate-request transmissions

to n (default 3).

iippccpp-rreessttaarrtt n

Set the IPCP restart interval (retransmission timeout) to n sec-

onds (default 3). iippppaarraamm string

Provides an extra parameter to the ip-up and ip-down scripts.

If this option is given, the string supplied is given as the 6th parameter to those scripts.

iippvv66ccpp-mmaaxx-ccoonnffiigguurree n

Set the maximum number of IPv6CP configure-request transmissions

to n (default 10).

iippvv66ccpp-mmaaxx-ffaaiilluurree n

Set the maximum number of IPv6CP configure-NAKs returned before

starting to send configure-Rejects instead to n (default 10).

iippvv66ccpp-mmaaxx-tteerrmmiinnaattee n

Set the maximum number of IPv6CP terminate-request transmissions

to n (default 3).

iippvv66ccpp-rreessttaarrtt n

Set the IPv6CP restart interval (retransmission timeout) to n seconds (default 3). iippxx Enable the IPXCP and IPX protocols. This option is presently only supported under Linux, and only if your kernel has been configured to include IPX support.

iippxx-nneettwwoorrkk n

Set the IPX network number in the IPXCP configure request frame to n, a hexadecimal number (without a leading 0x). There is no valid default. If this option is not specified, the network number is obtained from the peer. If the peer does not have the network number, the IPX protocol will not be started.

iippxx-nnooddee n::m

Set the IPX node numbers. The two node numbers are separated from each other with a colon character. The first number n is the local node number. The second number m is the peer's node number. Each node number is a hexadecimal number, at most 10

digits long. The node numbers on the ipx-network must be unique.

There is no valid default. If this option is not specified then the node numbers are obtained from the peer.

iippxx-rroouutteerr-nnaammee

Set the name of the router. This is a string and is sent to the peer as information data.

iippxx-rroouuttiinngg n

Set the routing protocol to be received by this option. More

than one instance of ipx-routing may be specified. The 'none'

option (0) may be specified as the only instance of ipx-routing.

The values may be 0 for NONE, 2 for RIP/SAP, and 4 for NLSP.

iippxxccpp-aacccceepptt-llooccaall

Accept the peer's NAK for the node number specified in the ipx-

node option. If a node number was specified, and non-zero, the

default is to insist that the value be used. If you include this option then you will permit the peer to override the entry of the node number.

iippxxccpp-aacccceepptt-nneettwwoorrkk

Accept the peer's NAK for the network number specified in the

ipx-network option. If a network number was specified, and non-

zero, the default is to insist that the value be used. If you include this option then you will permit the peer to override the entry of the node number.

iippxxccpp-aacccceepptt-rreemmoottee

Use the peer's network number specified in the configure request frame. If a node number was specified for the peer and this option was not specified, the peer will be forced to use the value which you have specified.

iippxxccpp-mmaaxx-ccoonnffiigguurree n

Set the maximum number of IPXCP configure request frames which the system will send to n. The default is 10.

iippxxccpp-mmaaxx-ffaaiilluurree n

Set the maximum number of IPXCP NAK frames which the local sys-

tem will send before it rejects the options. The default value is 3.

iippxxccpp-mmaaxx-tteerrmmiinnaattee n

Set the maximum nuber of IPXCP terminate request frames before the local system considers that the peer is not listening to them. The default value is 3. kkddeebbuugg n

Enable debugging code in the kernel-level PPP driver. The argu-

ment values depend on the specific kernel driver, but in general a value of 1 will enable general kernel debug messages. (Note that these messages are usually only useful for debugging the kernel driver itself.) For the Linux 2.2.x kernel driver, the value is a sum of bits: 1 to enable general debug messages, 2 to request that the contents of received packets be printed, and 4 to request that the contents of transmitted packets be printed. On most systems, messages printed by the kernel are logged by

syslog(1) to a file as directed in the /etc/syslog.conf configu-

ration file.

kkttuunnee Enables pppd to alter kernel settings as appropriate. Under

Linux, pppd will enable IP forwarding (i.e. set

/proc/sys/net/ipv4/ipforward to 1) if the proxyarp option is used, and will enable the dynamic IP address option (i.e. set /proc/sys/net/ipv4/ipdynaddr to 1) in demand mode if the local address changes.

llccpp-eecchhoo-ffaaiilluurree n

If this option is given, pppd will presume the peer to be dead

if n LCP echo-requests are sent without receiving a valid LCP

echo-reply. If this happens, pppd will terminate the connec-

tion. Use of this option requires a non-zero value for the lcp-

echo-interval parameter. This option can be used to enable pppd

to terminate after the physical connection has been broken (e.g., the modem has hung up) in situations where no hardware modem control lines are available.

llccpp-eecchhoo-iinntteerrvvaall n

If this option is given, pppd will send an LCP echo-request

frame to the peer every n seconds. Normally the peer should

respond to the echo-request by sending an echo-reply. This

option can be used with the lcp-echo-failure option to detect

that the peer is no longer connected.

llccpp-mmaaxx-ccoonnffiigguurree n

Set the maximum number of LCP configure-request transmissions to

n (default 10).

llccpp-mmaaxx-ffaaiilluurree n

Set the maximum number of LCP configure-NAKs returned before

starting to send configure-Rejects instead to n (default 10).

llccpp-mmaaxx-tteerrmmiinnaattee n

Set the maximum number of LCP terminate-request transmissions to

n (default 3).

llccpp-rreessttaarrtt n

Set the LCP restart interval (retransmission timeout) to n sec-

onds (default 3). lliinnkknnaammee name Sets the logical name of the link to name. Pppd will create a

file named pppppp-name..ppiidd in /var/run (or /etc/ppp on some sys-

tems) containing its process ID. This can be useful in deter-

mining which instance of pppd is responsible for the link to a

given peer system. This is a privileged option.

llooccaall Don't use the modem control lines. With this option, pppd will

ignore the state of the CD (Carrier Detect) signal from the modem and will not change the state of the DTR (Data Terminal Ready) signal. llooggffdd n

Send log messages to file descriptor n. Pppd will send log mes-

sages to at most one file or file descriptor (as well as sending the log messages to syslog), so this option and the llooggffiillee

option are mutually exclusive. The default is for pppd to send

log messages to stdout (file descriptor 1), unless the serial port is already open on stdout. llooggffiillee filename Append log messages to the file filename (as well as sending the log messages to syslog). The file is opened with the privileges

of the user who invoked pppd, in append mode.

llooggiinn Use the system password database for authenticating the peer using PAP, and record the user in the system wtmp file. Note

that the peer must have an entry in the /etc/ppp/pap-secrets

file as well as the system password database to be allowed access. mmaaxxccoonnnneecctt n Terminate the connection when it has been available for network traffic for n seconds (i.e. n seconds after the first network control protocol comes up). mmaaxxffaaiill n Terminate after n consecutive failed connection attempts. A value of 0 means no limit. The default value is 10. mmooddeemm Use the modem control lines. This option is the default. With

this option, pppd will wait for the CD (Carrier Detect) signal

from the modem to be asserted when opening the serial device (unless a connect script is specified), and it will drop the DTR

(Data Terminal Ready) signal briefly when the connection is ter-

minated and before executing the connect script. On Ultrix, this option implies hardware flow control, as for the crtscts option.

mmpp Enables the use of PPP multilink; this is an alias for the `mul-

tilink' option. This option is currently only available under Linux.

mmppppee-ssttaatteeffuull

Allow MPPE to use stateful mode. Stateless mode is still attempted first. The default is to disallow stateful mode. mmppsshhoorrttsseeqq

Enables the use of short (12-bit) sequence numbers in multilink

headers, as opposed to 24-bit sequence numbers. This option is

only available under Linux, and only has any effect if multilink is enabled (see the multilink option). mmrrrruu n Sets the Maximum Reconstructed Receive Unit to n. The MRRU is the maximum size for a received packet on a multilink bundle, and is analogous to the MRU for the individual links. This option is currently only available under Linux, and only has any effect if multilink is enabled (see the multilink option).

mmss-ddnnss

If pppd is acting as a server for Microsoft Windows clients,

this option allows pppd to supply one or two DNS (Domain Name

Server) addresses to the clients. The first instance of this option specifies the primary DNS address; the second instance (if given) specifies the secondary DNS address. (This option

was present in some older versions of pppd under the name ddnnss-

aaddddrr.)

mmss-wwiinnss

If pppd is acting as a server for Microsoft Windows or "Samba"

clients, this option allows pppd to supply one or two WINS (Win-

dows Internet Name Services) server addresses to the clients. The first instance of this option specifies the primary WINS address; the second instance (if given) specifies the secondary WINS address. mmuullttiilliinnkk Enables the use of the PPP multilink protocol. If the peer also supports multilink, then this link can become part of a bundle between the local system and the peer. If there is an existing

bundle to the peer, pppd will join this link to that bundle,

otherwise pppd will create a new bundle. See the MULTILINK sec-

tion below. This option is currently only available under Linux. nnaammee name Set the name of the local system for authentication purposes to

name. This is a privileged option. With this option, pppd will

use lines in the secrets files which have name as the second field when looking for a secret to use in authenticating the peer. In addition, unless overridden with the user option, name will be used as the name to send to the peer when authenticating

the local system to the peer. (Note that pppd does not append

the domain name to name.) nnooaaccccoommpp Disable Address/Control compression in both directions (send and receive). nnooaauutthh Do not require the peer to authenticate itself. This option is privileged. nnoobbssddccoommpp

Disables BSD-Compress compression; ppppppdd will not request or

agree to compress packets using the BSD-Compress scheme.

nnooccccpp Disable CCP (Compression Control Protocol) negotiation. This option should only be required if the peer is buggy and gets

confused by requests from pppd for CCP negotiation.

nnooccrrttssccttss Disable hardware flow control (i.e. RTS/CTS) on the serial port. If neither the crtscts nor the nocrtscts nor the cdtrcts nor the nocdtrcts option is given, the hardware flow control setting for the serial port is left unchanged. nnooccddttrrccttss This option is a synonym for nocrtscts. Either of these options will disable both forms of hardware flow control. nnooddeeffaauullttrroouuttee Disable the defaultroute option. The system administrator who

wishes to prevent users from creating default routes with pppd

can do so by placing this option in the /etc/ppp/options file. nnooddeeffllaattee

Disables Deflate compression; pppd will not request or agree to

compress packets using the Deflate scheme. nnooddeettaacchh Don't detach from the controlling terminal. Without this

option, if a serial device other than the terminal on the stan-

dard input is specified, pppd will fork to become a background

process. nnooeennddppooiinntt

Disables pppd from sending an endpoint discriminator to the peer

or accepting one from the peer (see the MULTILINK section below). This option should only be required if the peer is buggy. nnooiipp Disable IPCP negotiation and IP communication. This option should only be required if the peer is buggy and gets confused

by requests from pppd for IPCP negotiation.

nnooiippvv66 Disable IPv6CP negotiation and IPv6 communication. This option should only be required if the peer is buggy and gets confused

by requests from pppd for IPv6CP negotiation.

nnooiippddeeffaauulltt

Disables the default behaviour when no local IP address is spec-

ified, which is to determine (if possible) the local IP address

from the hostname. With this option, the peer will have to sup-

ply the local IP address during IPCP negotiation (unless it specified explicitly on the command line or in an options file). nnooiippxx Disable the IPXCP and IPX protocols. This option should only be required if the peer is buggy and gets confused by requests from

pppd for IPXCP negotiation.

nnookkttuunnee

Opposite of the ktune option; disables pppd from changing system

settings. nnoolloogg Do not send log messages to a file or file descriptor. This option cancels the llooggffdd and llooggffiillee options. nnoommaaggiicc

Disable magic number negotiation. With this option, pppd cannot

detect a looped-back line. This option should only be needed if

the peer is buggy. nnoommpp Disables the use of PPP multilink. This option is currently only available under Linux. nnoommppppee Disables MPPE (Microsoft Point to Point Encryption). This is the default.

nnoommppppee-4400

Disable 40-bit encryption with MPPE.

nnoommppppee-112288

Disable 128-bit encryption with MPPE.

nnoommppppee-ssttaatteeffuull

Disable MPPE stateful mode. This is the default. nnoommppsshhoorrttsseeqq

Disables the use of short (12-bit) sequence numbers in the PPP

multilink protocol, forcing the use of 24-bit sequence numbers.

This option is currently only available under Linux, and only has any effect if multilink is enabled. nnoommuullttiilliinnkk Disables the use of PPP multilink. This option is currently only available under Linux. nnooppccoommpp Disable protocol field compression negotiation in both the receive and the transmit direction. nnooppeerrssiisstt Exit once a connection has been made and terminated. This is

the default unless the persist or demand option has been speci-

fied. nnoopprreeddiiccttoorr11

Do not accept or agree to Predictor-1 compression.

nnoopprrooxxyyaarrpp Disable the proxyarp option. The system administrator who wishes to prevent users from creating proxy ARP entries with

pppd can do so by placing this option in the /etc/ppp/options

file.

nnoottttyy Normally, pppd requires a terminal device. With this option,

pppd will allocate itself a pseudo-tty master/slave pair and use

the slave as its terminal device. Pppd will create a child process to act as a `character shunt' to transfer characters

between the pseudo-tty master and its standard input and output.

Thus pppd will transmit characters on its standard output and

receive characters on its standard input even if they are not terminal devices. This option increases the latency and CPU overhead of transferring data over the ppp interface as all of the characters sent and received must flow through the character shunt process. An explicit device name may not be given if this option is used. nnoovvjj Disable Van Jacobson style TCP/IP header compression in both the transmit and the receive direction. nnoovvjjccccoommpp

Disable the connection-ID compression option in Van Jacobson

style TCP/IP header compression. With this option, pppd will

not omit the connection-ID byte from Van Jacobson compressed

TCP/IP headers, nor ask the peer to do so. ppaappccrryypptt

Indicates that all secrets in the /etc/ppp/pap-secrets file

which are used for checking the identity of the peer are

encrypted, and thus pppd should not accept a password which,

before encryption, is identical to the secret from the

/etc/ppp/pap-secrets file.

ppaapp-mmaaxx-aauutthhrreeqq n

Set the maximum number of PAP authenticate-request transmissions

to n (default 10).

ppaapp-rreessttaarrtt n

Set the PAP restart interval (retransmission timeout) to n sec-

onds (default 3).

ppaapp-ttiimmeeoouutt n

Set the maximum time that pppd will wait for the peer to authen-

ticate itself with PAP to n seconds (0 means no limit).

ppaassss-ffiilltteerr filter-expression

Specifies a packet filter to applied to data packets being sent or received to determine which packets should be allowed to pass. Packets which are rejected by the filter are silently discarded. This option can be used to prevent specific network daemons (such as routed) using up link bandwidth, or to provide

a very basic firewall capability. The filter-expression syntax

is as described for tcpdump(1), except that qualifiers which are inappropriate for a PPP link, such as eetthheerr and aarrpp, are not permitted. Generally the filter expression should be enclosed

in single-quotes to prevent whitespace in the expression from

being interpreted by the shell. Note that it is possible to apply different constraints to incoming and outgoing packets

using the iinnbboouunndd and oouuttbboouunndd qualifiers. This option is cur-

rently only available under Linux, and requires that the kernel

was configured to include PPP filtering support (CONFIGPPPFIL-

TER).

ppaasssswwoorrdd password-string

Specifies the password to use for authenticating to the peer. Use of this option is discouraged, as the password is likely to be visible to other users on the system (for example, by using ps(1)). ppeerrssiisstt Do not exit after a connection is terminated; instead try to reopen the connection. The mmaaxxffaaiill option still has an effect on persistent connections. pplluuggiinn filename Load the shared library object file filename as a plugin. This is a privileged option. If filename does not contain a slash

(/), pppd will look in the //uussrr//lliibb//ppppppdd//version directory for

the plugin, where version is the version number of pppd (for

example, 2.4.2). pprreeddiiccttoorr11

Request that the peer compress frames that it sends using Pre-

dictor-1 compression, and agree to compress transmitted frames

with Predictor-1 if requested. This option has no effect unless

the kernel driver supports Predictor-1 compression.

pprriivvggrroouupp group-name

Allows members of group group-name to use privileged options.

This is a privileged option. Use of this option requires care

as there is no guarantee that members of group-name cannot use

pppd to become root themselves. Consider it equivalent to

putting the members of group-name in the kmem or disk group.

pprrooxxyyaarrpp Add an entry to this system's ARP [Address Resolution Protocol] table with the IP address of the peer and the Ethernet address of this system. This will have the effect of making the peer appear to other systems to be on the local ethernet. ppttyy script Specifies that the command script is to be used to communicate rather than a specific terminal device. Pppd will allocate

itself a pseudo-tty master/slave pair and use the slave as its

terminal device. The script will be run in a child process with

the pseudo-tty master as its standard input and output. An

explicit device name may not be given if this option is used. (Note: if the record option is used in conjuction with the pty option, the child process will have pipes on its standard input and output.)

rreecceeiivvee-aallll

With this option, pppd will accept all control characters from

the peer, including those marked in the receive asyncmap. With-

out this option, pppd will discard those characters as specified

in RFC1662. This option should only be needed if the peer is buggy. rreeccoorrdd filename

Specifies that pppd should record all characters sent and

received to a file named filename. This file is opened in

append mode, using the user's user-ID and permissions. This

option is implemented using a pseudo-tty and a process to trans-

fer characters between the pseudo-tty and the real serial

device, so it will increase the latency and CPU overhead of transferring data over the ppp interface. The characters are

stored in a tagged format with timestamps, which can be dis-

played in readable form using the pppdump(8) program.

rreemmootteennaammee name Set the assumed name of the remote system for authentication purposes to name. rreemmootteennuummbbeerr number Set the assumed telephone number of the remote system for authentication purposes to number.

rreeffuussee-cchhaapp

With this option, pppd will not agree to authenticate itself to

the peer using CHAP.

rreeffuussee-mmsscchhaapp

With this option, pppd will not agree to authenticate itself to

the peer using MS-CHAP.

rreeffuussee-mmsscchhaapp-vv22

With this option, pppd will not agree to authenticate itself to

the peer using MS-CHAPv2.

rreeffuussee-eeaapp

With this option, pppd will not agree to authenticate itself to

the peer using EAP.

rreeffuussee-ppaapp

With this option, pppd will not agree to authenticate itself to

the peer using PAP.

rreeqquuiirree-cchhaapp

Require the peer to authenticate itself using CHAP [Challenge Handshake Authentication Protocol] authentication.

rreeqquuiirree-mmppppee

Require the use of MPPE (Microsoft Point to Point Encryption). This option disables all other compression types. This option

enables both 40-bit and 128-bit encryption. In order for MPPE

to successfully come up, you must have authenticated with either

MS-CHAP or MS-CHAPv2. This option is presently only supported

under Linux, and only if your kernel has been configured to include MPPE support.

rreeqquuiirree-mmppppee-4400

Require the use of MPPE, with 40-bit encryption.

rreeqquuiirree-mmppppee-112288

Require the use of MPPE, with 128-bit encryption.

rreeqquuiirree-mmsscchhaapp

Require the peer to authenticate itself using MS-CHAP [Microsft

Challenge Handshake Authentication Protocol] authentication.

rreeqquuiirree-mmsscchhaapp-vv22

Require the peer to authenticate itself using MS-CHAPv2

[Microsft Challenge Handshake Authentication Protocol, Version 2] authentication.

rreeqquuiirree-eeaapp

Require the peer to authenticate itself using EAP [Extensible Authentication Protocol] authentication.

rreeqquuiirree-ppaapp

Require the peer to authenticate itself using PAP [Password Authentication Protocol] authentication.

sshhooww-ppaasssswwoorrdd

When logging the contents of PAP packets, this option causes

pppd to show the password string in the log message.

ssiilleenntt With this option, pppd will not transmit LCP packets to initiate

a connection until a valid LCP packet is received from the peer

(as for the `passive' option with ancient versions of pppd).

ssyynncc Use synchronous HDLC serial encoding instead of asynchronous.

The device used by pppd with this option must have sync support.

Currently supports Microgate SyncLink adapters under Linux and FreeBSD 2.2.8 and later. uunniitt num Sets the ppp unit number (for a ppp0 or ppp1 etc interface name) for outbound connections. uuppddeettaacchh

With this option, pppd will detach from its controlling terminal

once it has successfully established the ppp connection (to the point where the first network control protocol, usually the IP control protocol, has come up). uusseehhoossttnnaammee Enforce the use of the hostname (with domain name appended, if

given) as the name of the local system for authentication pur-

poses (overrides the name option). This option is not normally needed since the name option is privileged. uusseeppeeeerrddnnss Ask the peer for up to 2 DNS server addresses. The addresses

supplied by the peer (if any) are passed to the /etc/ppp/ip-up

script in the environment variables DNS1 and DNS2, and the envi-

ronment variable USEPEERDNS will be set to 1. In addition, pppd

will create an /etc/ppp/resolv.conf file containing one or two nameserver lines with the address(es) supplied by the peer. uusseerr name Sets the name used for authenticating the local system to the peer to name.

vvjj-mmaaxx-sslloottss n

Sets the number of connection slots to be used by the Van Jacob-

son TCP/IP header compression and decompression code to n, which must be between 2 and 16 (inclusive). wweellccoommee script Run the executable or shell command specified by script before initiating PPP negotiation, after the connect script (if any) has completed. A value for this option from a privileged source

cannot be overridden by a non-privileged user.

xxoonnxxooffff Use software flow control (i.e. XON/XOFF) to control the flow of data on the serial port.

OPTIONS FILES

Options can be taken from files as well as the command line. Pppd reads options from the files /etc/ppp/options, ~/.ppprc and /etc/ppp/options.ttyname (in that order) before processing the options

on the command line. (In fact, the command-line options are scanned to

find the terminal name before the options.ttyname file is read.) In forming the name of the options.ttyname file, the initial /dev/ is removed from the terminal name, and any remaining / characters are replaced with dots.

An options file is parsed into a series of words, delimited by white-

space. Whitespace can be included in a word by enclosing the word in

double-quotes ("). A backslash (\) quotes the following character. A

hash (#) starts a comment, which continues until the end of the line.

There is no restriction on using the file or call options within an options file. SSEECCUURRIITTYY

pppd provides system administrators with sufficient access control that

PPP access to a server machine can be provided to legitimate users without fear of compromising the security of the server or the network it's on. This control is provided through restrictions on which IP addresses the peer may use, based on its authenticated identity (if

any), and through restrictions on which options a non-privileged user

may use. Several of pppd's options are privileged, in particular those

which permit potentially insecure configurations; these options are

only accepted in files which are under the control of the system admin-

istrator, or if pppd is being run by root.

The default behaviour of pppd is to allow an unauthenticated peer to

use a given IP address only if the system does not already have a route to that IP address. For example, a system with a permanent connection to the wider internet will normally have a default route, and thus all

peers will have to authenticate themselves in order to set up a connec-

tion. On such a system, the auth option is the default. On the other

hand, a system where the PPP link is the only connection to the inter-

net will not normally have a default route, so the peer will be able to use almost any IP address without authenticating itself.

As indicated above, some security-sensitive options are privileged,

which means that they may not be used by an ordinary non-privileged

user running a setuid-root pppd, either on the command line, in the

user's ~/.ppprc file, or in an options file read using the file option. Privileged options may be used in /etc/ppp/options file or in an

options file read using the call option. If pppd is being run by the

root user, privileged options can be used without restriction.

When opening the device, pppd uses either the invoking user's user ID

or the root UID (that is, 0), depending on whether the device name was specified by the user or the system administrator. If the device name comes from a privileged source, that is, /etc/ppp/options or an options

file read using the call option, pppd uses full root privileges when

opening the device. Thus, by creating an appropriate file under /etc/ppp/peers, the system administrator can allow users to establish a

ppp connection via a device which they would not normally have permis-

sion to access. Otherwise pppd uses the invoking user's real UID when

opening the device. AAUUTTHHEENNTTIICCAATTIIOONN Authentication is the process whereby one peer convinces the other of its identity. This involves the first peer sending its name to the other, together with some kind of secret information which could only come from the genuine authorized user of that name. In such an exchange, we will call the first peer the "client" and the other the "server". The client has a name by which it identifies itself to the server, and the server also has a name by which it identifies itself to

the client. Generally the genuine client shares some secret (or pass-

word) with the server, and authenticates itself by proving that it

knows that secret. Very often, the names used for authentication cor-

respond to the internet hostnames of the peers, but this is not essen-

tial.

At present, pppd supports three authentication protocols: the Password

Authentication Protocol (PAP), Challenge Handshake Authentication Pro-

tocol (CHAP), and Extensible Authentication Protocol (EAP). PAP involves the client sending its name and a cleartext password to the server to authenticate itself. In contrast, the server initiates the CHAP authentication exchange by sending a challenge to the client (the challenge packet includes the server's name). The client must respond with a response which includes its name plus a hash value derived from the shared secret and the challenge, in order to prove that it knows the secret. The PPP protocol, being symmetrical, allows both peers to require the

other to authenticate itself. In that case, two separate and indepen-

dent authentication exchanges will occur. The two exchanges could use different authentication protocols, and in principle, different names could be used in the two exchanges.

The default behaviour of pppd is to agree to authenticate if requested,

and to not require authentication from the peer. However, pppd will

not agree to authenticate itself with a particular protocol if it has no secrets which could be used to do so. Pppd stores secrets for use in authentication in secrets files

(/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP/MS-

CHAP/MS-CHAPv2). Both secrets files have the same format. The secrets

files can contain secrets for pppd to use in authenticating itself to

other systems, as well as secrets for pppd to use when authenticating

other systems to itself. Each line in a secrets file contains one secret. A given secret is

specific to a particular combination of client and server - it can only

be used by that client to authenticate itself to that server. Thus each line in a secrets file has at least 3 fields: the name of the client, the name of the server, and the secret. These fields may be followed by a list of the IP addresses that the specified client may use when connecting to the specified server. A secrets file is parsed into words as for a options file, so the client name, server name and secrets fields must each be one word, with any embedded spaces or other special characters quoted or escaped. Note that case is significant in the client and server names and in the secret. If the secret starts with an `@', what follows is assumed to be the name of a file from which to read the secret. A "*" as the client or

server name matches any name. When selecting a secret, pppd takes the

best match, i.e. the match with the fewest wildcards.

Any following words on the same line are taken to be a list of accept-

able IP addresses for that client. If there are only 3 words on the

line, or if the first word is "-", then all IP addresses are disal-

lowed. To allow any address, use "*". A word starting with "!" indi-

cates that the specified address is not acceptable. An address may be followed by "/" and a number n, to indicate a whole subnet, i.e. all addresses which have the same value in the most significant n bits. In this form, the address may be followed by a plus sign ("+") to indicate

that one address from the subnet is authorized, based on the ppp net-

work interface unit number in use. In this case, the host part of the address will be set to the unit number plus one. Thus a secrets file contains both secrets for use in authenticating other hosts, plus secrets which we use for authenticating ourselves to

others. When pppd is authenticating the peer (checking the peer's

identity), it chooses a secret with the peer's name in the first field and the name of the local system in the second field. The name of the local system defaults to the hostname, with the domain name appended if the domain option is used. This default can be overridden with the name option, except when the usehostname option is used.

When pppd is choosing a secret to use in authenticating itself to the

peer, it first determines what name it is going to use to identify itself to the peer. This name can be specified by the user with the user option. If this option is not used, the name defaults to the name of the local system, determined as described in the previous paragraph.

Then pppd looks for a secret with this name in the first field and the

peer's name in the second field. Pppd will know the name of the peer if CHAP or EAP authentication is being used, because the peer will have

sent it in the challenge packet. However, if PAP is being used, pppd

will have to determine the peer's name from the options specified by the user. The user can specify the peer's name directly with the remotename option. Otherwise, if the remote IP address was specified by a name (rather than in numeric form), that name will be used as the

peer's name. Failing that, pppd will use the null string as the peer's

name. When authenticating the peer with PAP, the supplied password is first compared with the secret from the secrets file. If the password doesn't match the secret, the password is encrypted using crypt() and checked against the secret again. Thus secrets for authenticating the peer can be stored in encrypted form if desired. If the papcrypt option is given, the first (unencrypted) comparison is omitted, for better security.

Furthermore, if the login option was specified, the username and pass-

word are also checked against the system password database. Thus, the

system administrator can set up the pap-secrets file to allow PPP

access only to certain users, and to restrict the set of IP addresses that each user can use. Typically, when using the login option, the

secret in /etc/ppp/pap-secrets would be "", which will match any pass-

word supplied by the peer. This avoids the need to have the same secret in two places. Authentication must be satisfactorily completed before IPCP (or any other Network Control Protocol) can be started. If the peer is

required to authenticate itself, and fails to do so, pppd will termi-

nated the link (by closing LCP). If IPCP negotiates an unacceptable IP address for the remote host, IPCP will be closed. IP packets can only be sent or received when IPCP is open.

In some cases it is desirable to allow some hosts which can't authenti-

cate themselves to connect and use one of a restricted set of IP addresses, even when the local host generally requires authentication.

If the peer refuses to authenticate itself when requested, pppd takes

that as equivalent to authenticating with PAP using the empty string

for the username and password. Thus, by adding a line to the pap-

secrets file which specifies the empty string for the client and pass-

word, it is possible to allow restricted access to hosts which refuse to authenticate themselves. RROOUUTTIINNGG

When IPCP negotiation is completed successfully, pppd will inform the

kernel of the local and remote IP addresses for the ppp interface. This is sufficient to create a host route to the remote end of the

link, which will enable the peers to exchange IP packets. Communica-

tion with other machines generally requires further modification to routing tables and/or ARP (Address Resolution Protocol) tables. In most cases the defaultroute and/or proxyarp options are sufficient for this, but in some cases further intervention is required. The

/etc/ppp/ip-up script can be used for this.

Sometimes it is desirable to add a default route through the remote host, as in the case of a machine whose only connection to the Internet

is through the ppp interface. The defaultroute option causes pppd to

create such a default route when IPCP comes up, and delete it when the link is terminated. In some cases it is desirable to use proxy ARP, for example on a server

machine connected to a LAN, in order to allow other hosts to communi-

cate with the remote host. The proxyarp option causes pppd to look for

a network interface on the same subnet as the remote host (an interface

supporting broadcast and ARP, which is up and not a point-to-point or

loopback interface). If found, pppd creates a permanent, published ARP

entry with the IP address of the remote host and the hardware address of the network interface found. When the demand option is used, the interface IP addresses have already

been set at the point when IPCP comes up. If pppd has not been able to

negotiate the same addresses that it used to configure the interface (for example when the peer is an ISP that uses dynamic IP address

assignment), pppd has to change the interface IP addresses to the nego-

tiated addresses. This may disrupt existing connections, and the use of demand dialing with peers that do dynamic IP address assignment is not recommended. MMUULLTTIILLIINNKK Multilink PPP provides the capability to combine two or more PPP links between a pair of machines into a single `bundle', which appears as a

single virtual PPP link which has the combined bandwidth of the indi-

vidual links. Currently, multilink PPP is only supported under Linux. Pppd detects that the link it is controlling is connected to the same peer as another link using the peer's endpoint discriminator and the authenticated identity of the peer (if it authenticates itself). The endpoint discriminator is a block of data which is hopefully unique for

each peer. Several types of data can be used, including locally-

assigned strings of bytes, IP addresses, MAC addresses, randomly

strings of bytes, or E-164 phone numbers. The endpoint discriminator

sent to the peer by pppd can be set using the endpoint option.

In circumstances the peer may send no endpoint discriminator or a non-

unique value. The optional bundle option adds an extra string which is added to the peer's endpoint discriminator and authenticated identity when matching up links to be joined together in a bundle. The bundle option can also be used to allow the establishment of multiple bundles between the local system and the peer. Pppd uses a TDB database in

/var/run/pppd.tdb to match up links.

Assuming that multilink is enabled and the peer is willing to negotiate

multilink, then when pppd is invoked to bring up the first link to the

peer, it will detect that no other link is connected to the peer and create a new bundle, that is, another ppp network interface unit. When

another pppd is invoked to bring up another link to the peer, it will

detect the existing bundle and join its link to it. Currently, if the

first pppd terminates (for example, because of a hangup or a received

signal) the bundle is destroyed. EEXXAAMMPPLLEESS The following examples assume that the /etc/ppp/options file contains the auth option (as in the default /etc/ppp/options file in the ppp distribution).

Probably the most common use of pppd is to dial out to an ISP. This

can be done with a command such as

pppd call isp

where the /etc/ppp/peers/isp file is set up by the system administrator to contain something like this: ttyS0 19200 crtscts

connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'

noauth In this example, we are using chat to dial the ISP's modem and go

through any logon sequence required. The /etc/ppp/chat-isp file con-

tains the script used by chat; it could for example contain something like this: ABORT "NO CARRIER" ABORT "NO DIALTONE"

ABORT "ERROR"

ABORT "NO ANSWER" ABORT "BUSY" ABORT "Username/Password Incorrect" "" "at" OK "at&d0&c1" OK "atdt2468135" "name:" "^Umyuserid" "word:" "\qmypassword" "ispts" "\q^Uppp"

"~-^Uppp-~"

See the chat(8) man page for details of chat scripts.

Pppd can also be used to provide a dial-in ppp service for users. If

the users already have login accounts, the simplest way to set up the

ppp service is to let the users log in to their accounts and run pppd

(installed setuid-root) with a command such as

pppd proxyarp

To allow a user to use the PPP facilities, you need to allocate an IP

address for that user's machine and create an entry in /etc/ppp/pap-

secrets or /etc/ppp/chap-secrets (depending on which authentication

method the PPP implementation on the user's machine supports), so that the user's machine can authenticate itself. For example, if Joe has a machine called "joespc" which is to be allowed to dial in to the machine called "server" and use the IP address joespc.my.net, you would

add an entry like this to /etc/ppp/pap-secrets or /etc/ppp/chap-

secrets: joespc server "joe's secret" joespc.my.net Alternatively, you can create a username called (for example) "ppp",

whose login shell is pppd and whose home directory is /etc/ppp.

Options to be used when pppd is run this way can be put in

/etc/ppp/.ppprc. If your serial connection is any more complicated than a piece of wire, you may need to arrange for some control characters to be escaped. In particular, it is often useful to escape XON (^Q) and XOFF (^S), using asyncmap a0000. If the path includes a telnet, you probably should escape ^] as well (asyncmap 200a0000). If the path includes an rlogin, you will need to use the escape ff option on the end which is running

the rlogin client, since many rlogin implementations are not transpar-

ent; they will remove the sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the stream. DIAGNOSTICS Messages are sent to the syslog daemon using facility LOGRAS. (This

can be overriden by recompiling pppd with the macro LOGPPP defined as

the desired facility.) See the syslog(8) documentation for details of where the syslog daemon will write the messages. On most systems, the

syslog daemon uses the /etc/syslog.conf file to specify the destina-

tion(s) for syslog messages. You may need to edit that file to suit. The debug option causes the contents of all control packets sent or

received to be logged, that is, all LCP, PAP, CHAP, EAP or IPCP pack-

ets. This can be useful if the PPP negotiation does not succeed or if authentication fails. If debugging is enabled at compile time, the debug option also causes other debugging messages to be logged. Debugging can also be enabled or disabled by sending a SIGUSR1 signal

to the pppd process. This signal acts as a toggle.

EEXXIITT SSTTAATTUUSS

The exit status of pppd is set to indicate whether any error was

detected, or the reason for the link being terminated. The values used are: 00 Pppd has detached, or otherwise the connection was successfully established and terminated at the peer's request. 11 An immediately fatal error of some kind occurred, such as an essential system call failing, or running out of virtual memory. 22 An error was detected in processing the options given, such as two mutually exclusive options being used.

33 Pppd is not setuid-root and the invoking user is not root.

44 The kernel does not support PPP, for example, the PPP kernel driver is not included or cannot be loaded. 55 Pppd terminated because it was sent a SIGINT, SIGTERM or SIGHUP signal. 66 The serial port could not be locked. 77 The serial port could not be opened.

88 The connect script failed (returned a non-zero exit status).

99 The command specified as the argument to the pty option could not be run. 1100 The PPP negotiation failed, that is, it didn't reach the point where at least one network protocol (e.g. IP) was running. 1111 The peer system failed (or refused) to authenticate itself. 1122 The link was established successfully and terminated because it was idle. 1133 The link was established successfully and terminated because the connect time limit was reached. 1144 Callback was negotiated and an incoming call should arrive shortly. 1155 The link was terminated because the peer is not responding to echo requests. 1166 The link was terminated by the modem hanging up. 1177 The PPP negotiation failed because serial loopback was detected.

1188 The init script failed (returned a non-zero exit status).

1199 We failed to authenticate ourselves to the peer. SSCCRRIIPPTTSS Pppd invokes scripts at various stages in its processing which can be

used to perform site-specific ancillary processing. These scripts are

usually shell scripts, but could be executable code files instead. Pppd does not wait for the scripts to finish. The scripts are executed

as root (with the real and effective user-id set to 0), so that they

can do things such as update routing tables or run privileged daemons. Be careful that the contents of these scripts do not compromise your system's security. Pppd runs the scripts with standard input, output and error redirected to /dev/null, and with an environment that is empty except for some environment variables that give information about

the link. The environment variables that pppd sets are:

DDEEVVIICCEE The name of the serial tty device being used.

IFNAME h nm o te ewr itrae en ue.

IIPPLLOOCCAALL The IP address for the local end of the link. This is only set when IPCP has come up. IIPPRREEMMOOTTEE The IP address for the remote end of the link. This is only set when IPCP has come up.

PEERNAME

The authenticated name of the peer. This is only set if the peer authenticates itself. SSPPEEEEDD The baud rate of the tty device. OORRIIGGUUIIDD

The real user-id of the user who invoked pppd.

PPPLOGNAME

The username of the real user-id that invoked pppd. This is

always set.

For the ip-down and auth-down scripts, pppd also sets the following

variables giving statistics for the connection: CCOONNNNEECCTTTTIIMMEE The number of seconds from when the PPP negotiation started until the connection was terminated. BBYYTTEESSSSEENNTT

The number of bytes sent (at the level of the serial port) dur-

ing the connection. BBYYTTEESSRRCCVVDD The number of bytes received (at the level of the serial port) during the connection.

LINKNAME

The logical name of the link, set with the linkname option. DDNNSS11 If the peer supplies DNS server addresses, this variable is set to the first DNS server address supplied. DDNNSS22 If the peer supplies DNS server addresses, this variable is set to the second DNS server address supplied. Pppd invokes the following scripts, if they exist. It is not an error if they don't exist.

//eettcc//pppppp//aauutthh-uupp

A program or script which is executed after the remote system successfully authenticates itself. It is executed with the parameters

interface-name peer-name user-name tty-device speed

Note that this script is not executed if the peer doesn't authenticate itself, for example when the noauth option is used.

//eettcc//pppppp//aauutthh-ddoowwnn

A program or script which is executed when the link goes down,

if /etc/ppp/auth-up was previously executed. It is executed in

the same manner with the same parameters as /etc/ppp/auth-up.

//eettcc//pppppp//iipp-uupp

A program or script which is executed when the link is available for sending and receiving IP packets (that is, IPCP has come up). It is executed with the parameters

interface-name tty-device speed local-IP-address remote-IP-

address ipparam

//eettcc//pppppp//iipp-ddoowwnn

A program or script which is executed when the link is no longer available for sending and receiving IP packets. This script can

be used for undoing the effects of the /etc/ppp/ip-up script.

It is invoked in the same manner and with the same parameters as

the ip-up script.

//eettcc//pppppp//iippvv66-uupp

Like /etc/ppp/ip-up, except that it is executed when the link is

available for sending and receiving IPv6 packets. It is executed with the parameters

interface-name tty-device speed local-link-local-address remote-

link-local-address ipparam

//eettcc//pppppp//iippvv66-ddoowwnn

Similar to /etc/ppp/ip-down, but it is executed when IPv6 pack-

ets can no longer be transmitted on the link. It is executed

with the same parameters as the ipv6-up script.

//eettcc//pppppp//iippxx-uupp

A program or script which is executed when the link is available for sending and receiving IPX packets (that is, IPXCP has come up). It is executed with the parameters

interface-name tty-device speed network-number local-IPX-node-

address remote-IPX-node-address local-IPX-routing-protocol

remote-IPX-routing-protocol local-IPX-router-name remote-IPX-

router-name ipparam pppd-pid

The local-IPX-routing-protocol and remote-IPX-routing-protocol

field may be one of the following: NONE to indicate that there is no routing protocol RIP to indicate that RIP/SAP should be used NLSP to indicate that Novell NLSP should be used RIP NLSP to indicate that both RIP/SAP and NLSP should be used

//eettcc//pppppp//iippxx-ddoowwnn

A program or script which is executed when the link is no longer available for sending and receiving IPX packets. This script

can be used for undoing the effects of the /etc/ppp/ipx-up

script. It is invoked in the same manner and with the same

parameters as the ipx-up script.

FILES //vvaarr//rruunn//ppppppn..ppiidd (BSD or Linux), //eettcc//pppppp//ppppppn..ppiidd (others)

Process-ID for pppd process on ppp interface unit n.

//vvaarr//rruunn//pppppp-name..ppiidd (BSD or Linux),

//eettcc//pppppp//pppppp-name..ppiidd (others) Process-ID for pppd process for

logical link name (see the linkname option).

//eettcc//pppppp//ppaapp-sseeccrreettss

Usernames, passwords and IP addresses for PAP authentication. This file should be owned by root and not readable or writable by any other user. Pppd will log a warning if this is not the case.

//eettcc//pppppp//cchhaapp-sseeccrreettss

Names, secrets and IP addresses for CHAP/MS-CHAP/MS-CHAPv2

authentication. As for /etc/ppp/pap-secrets, this file should

be owned by root and not readable or writable by any other user. Pppd will log a warning if this is not the case. //eettcc//pppppp//ooppttiioonnss

System default options for pppd, read before user default

options or command-line options.

~~//..pppppprrcc User default options, read before /etc/ppp/options.ttyname. //eettcc//pppppp//ooppttiioonnss..ttyname System default options for the serial port being used, read after ~/.ppprc. In forming the ttyname part of this filename, an initial /dev/ is stripped from the port name (if present), and any slashes in the remaining part are converted to dots. //eettcc//pppppp//ppeeeerrss

A directory containing options files which may contain privi-

leged options, even if pppd was invoked by a user other than

root. The system administrator can create options files in this

directory to permit non-privileged users to dial out without

requiring the peer to authenticate, but only to certain trusted peers.

Some limited degree of control can be exercised over a running pppd

process by sending it a signal from the list below. SSIIGGIINNTT,, SSIIGGTTEERRMM

These signals cause pppd to terminate the link (by closing LCP),

restore the serial device settings, and exit.

SSIIGGHHUUPP This signal causes pppd to terminate the link, restore the

serial device settings, and close the serial device. If the

persist or demand option has been specified, pppd will try to

reopen the serial device and start another connection (after the

holdoff period). Otherwise pppd will exit. If this signal is

received during the holdoff period, it causes pppd to end the

holdoff period immediately. SSIIGGUUSSRR11 This signal toggles the state of the debug option. SSIIGGUUSSRR22

This signal causes pppd to renegotiate compression. This can be

useful to re-enable compression after it has been disabled as a

result of a fatal decompression error. (Fatal decompression errors generally indicate a bug in one or other implementation.) AUTHORS Paul Mackerras (Paul.Mackerras@samba.org), based on earlier work by Drew Perkins, Brad Clements, Karl Fox, Greg Christy, and Brad Parker. PPPD(8)