# pppd

## NAME



           pppd - Point-to-Point Protocol Daemon
    


## SYNOPSIS



           **pppd**[ _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 information to the peer.
           PPP can be used with other network protocols besides IP, but such
           use is becoming increasingly rare.
    


## FREQUENTLY USED OPTIONS



           _ttyname_
                  Use the serial port called _ttyname_ to communicate with the
                  peer.  If _ttyname_ does not begin with a slash (/), 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 Linux,
                  4.4BSD and NetBSD, any speed can be specified.  Other
                  systems (e.g. SunOS) only support the commonly-used baud
                  rates.
    
           **asyncmap** _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.
    
           **auth** 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.
    
           **call** _name_
                  Read additional 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.
    
           **connect** _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-
                  privileged user.
    
           **crtscts**
                  Specifies that pppd should set the serial port to use
                  hardware flow control using the RTS and CTS signals in the
                  RS-232 interface.  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.
    
           **defaultroute**
                  Add a default route to the system routing tables, using the
                  peer as the gateway, when IPCP negotiation is successfully
                  completed.  This entry is removed when the PPP connection
                  is broken.  This option is privileged if the _nodefaultroute_
                  option has been specified.
    
           **defaultroute-metric**
                  Define the metric of the _defaultroute_.  By default the
                  default route will be added with a metric of 0.  This
                  option is privileged.
    
           **disconnect** _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 disconnect script is not run if the modem
                  has already hung up.  A value for this option from a
                  privileged source cannot be overridden by a non-privileged
                  user.
    
           **escape** _xx,yy,..._
                  Specifies that certain characters should be escaped on
                  transmission (regardless of whether the peer requests them
                  to be escaped with its async control character map).  The
                  characters to be escaped are specified as a list of hex
                  numbers separated by commas.  Note that almost any
                  character can be specified for the _escape_ option, unlike
                  the _asyncmap_ option which only allows control characters to
                  be specified.  The characters which may not be escaped are
                  those with hex values 0x20 - 0x3f or 0x5e.
    
           **file** _name_
                  Read options from file _name_ (the format is described
                  below).  The file must be readable by the user who has
                  invoked pppd.
    
           **init** _script_
                  Execute the command specified by _script_ , by passing it to a
                  shell, to initialize the serial line.  This script would
                  typically use the chat(8) program to configure the modem to
                  enable auto answer.  A value for this option from a
                  privileged source cannot be overridden by a non-privileged
                  user.
    
           **lock** Specifies that pppd should create a UUCP-style lock file
                  for the serial device to ensure exclusive access to the
                  device.  By default, pppd will not create a lock file.
    
           **mru** _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.
    
           **mtu** _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.
    
           **passive**
                  Enables the "passive" option in the LCP.  With this option,
                  pppd will attempt to initiate a connection; if no reply is
                  received from the peer, pppd will then just wait passively
                  for a valid LCP packet from the peer, instead of exiting,
                  as it would without this option.
    


## OPTIONS



           _< local_IP_address>_**:**_< remote_IP_address>_
                  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.
    
           **+ipv6** Enable the IPv6CP and IPv6 protocols.
    
           **ipv6** _< local_interface_identifier>_,_< remote_interface_identifier>_
                  Set the local and/or remote 64-bit interface identifier.
                  Either one may be omitted. The identifier must be specified
                  in standard ASCII notation of IPv6 addresses (e.g.
                  ::dead:beef). If the _ipv6cp-use-ipaddr_ option is given, the
                  local identifier is the local IPv4 address and the remote
                  identifier is the remote IPv4 address (see above).  If the
                  _ipv6cp-use-remotenumber_ option is given, the remote
                  identifier is set to the value from _remotenumber_ option.
                  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 set local
                  identifier.  Otherwise both local and remote identifiers
                  are randomized.
    
           **active-filter** _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-dialling mode.  This option
                  is useful in conjunction with the **idle** option if there are
                  packets being sent or received regularly over the link (for
                  example, routing information packets) which would otherwise
                  prevent the link from ever appearing to be idle.  The
                  _filter-expression_ syntax is as described for tcpdump(1),
                  except that qualifiers which are inappropriate for a PPP
                  link, such as **ether** and **arp** , 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 filtering support
                  (CONFIG_PPP_FILTER).  Note that it is possible to apply
                  different constraints to incoming and outgoing packets
                  using the **inbound** and **outbound** qualifiers.
    
           **allow-ip** _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).
    
           **allow-number** _number_
                  Allow peers to connect from the given telephone number.  A
                  trailing `*' character will match all numbers beginning
                  with the leading part.
    
           **bsdcomp** _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 corresponding direction.  Use
                  _nobsdcomp_ or _bsdcomp 0_ to disable BSD-Compress compression
                  entirely.
    
           **ca** _ca-file_
                  (EAP-TLS, or PEAP) Use the file _ca-file_ as the X.509
                  Certificate Authority (CA) file (in PEM format), needed for
                  setting up an EAP-TLS connection.  This option is used on
                  the client-side in conjunction with the **cert** and **key**
                  options.  Either _ca_ , or _capath_ options are required for
                  PEAP. EAP-TLS may also use the entry in eaptls-client or
                  eaptls-server for a CA certificate associated with a
                  particular peer.
    
           **capath** _path_
                  (EAP-TLS, or PEAP) Specify a location that contains public
                  CA certificates.  Either _ca_ , or _capath_ options are required
                  for PEAP.
    
           **cdtrcts**
                  Use a non-standard hardware flow control (i.e. DTR/CTS) to
                  control the flow of data on the serial port.  If neither
                  the _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.
    
           **cert** _certfile_
                  (EAP-TLS) Use the file _certfile_ as the X.509 certificate
                  (in PEM format), needed for setting up an EAP-TLS
                  connection. This option is used on the client-side in
                  conjunction with the **ca** and **key** options.
    
           **chap-interval** _n_
                  If this option is given, pppd will rechallenge the peer
                  every _n_ seconds.
    
           **chap-max-challenge** _n_
                  Set the maximum number of CHAP challenge transmissions to _n_
                  (default 10).
    
           **chap-restart** _n_
                  Set the CHAP restart interval (retransmission timeout for
                  challenges) to _n_ seconds (default 3).
    
           **chap-timeout** _n_
                  Set timeout for CHAP authentication by peer to _n_ seconds
                  (default 60).
    
           **chapms-strip-domain**
                  Some Windows 9x/ME clients might be transmitting the MS
                  domain before the username in the provided client name.
                  This option enables stripping the domain from the client
                  name on the server side before matching it against the
                  secret file.
    
           **child-timeout** _n_
                  When exiting, wait for up to _n_ seconds for any child
                  processes (such as the command specified with the **pty**
                  command) to exit before exiting.  At the end of the
                  timeout, pppd will send a SIGTERM signal to any remaining
                  child processes and exit.  A value of 0 means no timeout,
                  that is, pppd will wait until all child processes have
                  exited.
    
           **connect-delay** _n_
                  Wait for up to _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 **connect** or **pty** option
                  is used.
    
           **crl** _filename_
                  (EAP-TLS, or PEAP) Use the file _filename_ as the Certificate
                  Revocation List to check for the validity of the peer's
                  certificate. This option is not mandatory for setting up a
                  TLS connection. Also see the **crl-dir** option.
    
           **crl-dir** _directory_
                  (EAP-TLS, or PEAP) Use the directory _directory_ to scan for
                  CRL files in has format ($hash.r0) to check for the
                  validity of the peer's certificate.  This option is not
                  mandatory for setting up a TLS connection.  Also see the
                  **crl** option.
    
           **debug** 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 appropriately (see syslog.conf(5)).
    
           **default-asyncmap**
                  Disable asyncmap negotiation, forcing all control
                  characters to be escaped for both the transmit and the
                  receive direction.
    
           **default-mru**
                  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.
    
           **defaultroute6**
                  Add a default IPv6 route to the system routing tables,
                  using the peer as the gateway, when IPv6CP negotiation is
                  successfully completed.  This entry is removed when the PPP
                  connection is broken.  This option is privileged if the
                  _nodefaultroute6_ option has been specified.  **WARNING: Do not**
                  **enable this option by default**.  IPv6 routing tables are
                  managed by kernel (as apposite to IPv4) and IPv6 default
                  route is configured by kernel automatically too based on
                  ICMPv6 Router Advertisement packets.  This option may
                  conflict with kernel IPv6 route setup and should be used
                  only for broken IPv6 networks.
    
           **defaultroute6-metric**
                  Define the metric of the _defaultroute6_.  By default the
                  default route will be added with a metric of 0.  This
                  option is privileged.
    
           **deflate** _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
                  corresponding direction.  Use _nodeflate_ or _deflate 0_ to
                  disable Deflate compression entirely.  (Note: pppd requests
                  Deflate compression in preference to BSD-Compress if the
                  peer can do either.)
    
           **demand** Initiate the link only on demand, i.e. when data traffic is
                  present.  With this option, the remote IP address may be
                  specified by the user on the command line or in an options
                  file, or if not, pppd will use an arbitrary address in the
                  10.x.x.x range.  Pppd will initially configure the
                  interface and enable it for IP traffic without connecting
                  to the peer.  When traffic is available, 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 conjunction with the _demand_ option.
    
           **domain** _d_
                  Append the domain name _d_ to the local host name for
                  authentication purposes.  For example, if gethostname()
                  returns the name porsche, but the fully qualified domain
                  name is porsche.Quotron.COM, you 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.
    
           **dryrun** With the **dryrun** option, pppd will print out all the option
                  values which have been set and then exit, after parsing the
                  command line and options files and checking the option
                  values, but before initiating the link.  The option values
                  are logged at level info, and also printed to standard
                  output unless the device on standard output is the device
                  that pppd would be using to communicate with the peer.
    
           **dump** With the **dump** option, pppd will print out all the option
                  values which have been set.  This option is like the **dryrun**
                  option except that pppd proceeds as normal rather than
                  exiting.
    
           **enable-session**
                  Enables session accounting via PAM or wtwp/wtmpx, as
                  appropriate.  When PAM is enabled, the PAM "account" and
                  "session" module stacks determine behavior, and are enabled
                  for all PPP authentication protocols.  When PAM is
                  disabled, wtmp/wtmpx entries are recorded regardless of
                  whether the peer name identifies a valid user on the local
                  system, making peers visible in the last(1) log.  This
                  feature is automatically enabled when the pppd **login** option
                  is used.  Session accounting is disabled by default.
    
           **endpoint** _< epdisc>_
                  Sets the endpoint discriminator sent by the local machine
                  to the peer during multilink negotiation to _< epdisc>_.  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 **null** or of the form _type_ :_value_ , where type is a
                  decimal number or one of the strings **local** , **IP** , **MAC** , **magic** ,
                  or **phone**.  The value is an IP address in dotted-decimal
                  notation for the **IP** 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.
    
           **eap-interval** _n_
                  If this option is given and pppd authenticates the peer
                  with EAP (i.e., is the server), pppd will restart EAP
                  authentication every _n_ seconds.  For EAP SRP-SHA1, see also
                  the **srp-interval** option, which enables lightweight
                  rechallenge.
    
           **eap-max-rreq** _n_
                  Set the maximum number of EAP Requests to which pppd will
                  respond (as a client) without hearing EAP Success or
                  Failure.  (Default is 20.)
    
           **eap-max-sreq** _n_
                  Set the maximum number of EAP Requests that pppd will issue
                  (as a server) while attempting authentication.  (Default is
                  10.)
    
           **eap-restart** _n_
                  Set the retransmit timeout for EAP Requests when acting as
                  a server (authenticator).  (Default is 3 seconds.)
    
           **eap-timeout** _n_
                  Set the maximum time to wait for the peer to send an EAP
                  Request when acting as a client (authenticatee).  (Default
                  is 20 seconds.)
    
           **hide-password**
                  When logging the contents of PAP packets, this option
                  causes pppd to exclude the password string from the log.
                  This is the default.
    
           **holdoff** _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, connect time expired, modem hangup or user
                  request.
    
           **idle** _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 packets) are being sent or received.  Note: it is not
                  advisable to use this option with the _persist_ option
                  without the _demand_ option.  If the **active-filter** option is
                  given, data packets which are rejected by the specified
                  activity filter also count as the link being idle.
    
           **ipcp-accept-local**
                  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.
    
           **ipcp-accept-remote**
                  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.
    
           **ipcp-max-configure** _n_
                  Set the maximum number of IPCP configure-request
                  transmissions to _n_ (default 10).
    
           **ipcp-max-failure** _n_
                  Set the maximum number of IPCP configure-NAKs returned
                  before starting to send configure-Rejects instead to _n_
                  (default 10).
    
           **ipcp-max-terminate** _n_
                  Set the maximum number of IPCP terminate-request
                  transmissions to _n_ (default 3).
    
           **ipcp-no-address**
                  Disable negotiation of addresses via IP-Address IPCP
                  option.
    
           **ipcp-no-addresses**
                  Disable negotiation of addresses via old-style deprecated
                  IP-Addresses IPCP option. pppd by default try to use new-
                  style IP-Address IPCP option.  If new-style is not
                  supported by peer or is disabled by **ipcp-no-address** option
                  then pppd fallbacks to old-style deprecated IP-Addresses
                  IPCP option.  When both new-style and old-style are
                  disabled by both **ipcp-no-address** and **ipcp-no-addresses**
                  options then negotiation of IP addresses is completely
                  disabled.
    
           **ipcp-restart** _n_
                  Set the IPCP restart interval (retransmission timeout) to _n_
                  seconds (default 3).
    
           **ipparam** _string_
                  Provides an extra parameter most of the notification
                  scripts, most notably ip-up, ip-pre-up, ip-down, ipv6-up,
                  ipv6-down, auth-up and auth-down scripts.  If this option
                  is given, the _string_ supplied is given as the 6th parameter
                  to those scripts.
    
           **ipv6cp-accept-local**
                  With this option, pppd will accept the peer's idea of our
                  local IPv6 interface identifier, even if the local IPv6
                  interface identifier was specified in an option.
    
           **ipv6cp-accept-remote**
                  With this option, pppd will accept the peer's idea of its
                  (remote) IPv6 interface identifier, even if the remote IPv6
                  interface identifier was specified in an option.
    
           **ipv6cp-noremote**
                  Allow pppd to operate without having an IPv6 link local
                  address for the peer.  This option is only available under
                  Linux.  Normally, pppd will request the peer's IPv6
                  interface identifier (used for composing IPv6 link local
                  address), and if the peer does not supply it, pppd will
                  generate one for the peer.  With this option, if the peer
                  does not supply its IPv6 interface identifier, pppd will
                  not ask the peer for it, and will not set the destination
                  IPv6 link local address of the ppp interface.  In this
                  situation, the ppp interface can be used for routing by
                  creating device routes, but the peer itself cannot be
                  addressed directly for IPv6 traffic until the peer starts
                  announcing ICMPv6 Router Advertisement or ICMPv6 Neighbor
                  Advertisement packets.  Note that IPv6 router must announce
                  ICMPv6 Router Advertisement packets.
    
           **ipv6cp-nosendip**
                  Don't send our local IPv6 interface identifier to peer
                  during IPv6 interface identifier negotiation.
    
           **ipv6cp-max-configure** _n_
                  Set the maximum number of IPv6CP configure-request
                  transmissions to _n_ (default 10).
    
           **ipv6cp-max-failure** _n_
                  Set the maximum number of IPv6CP configure-NAKs returned
                  before starting to send configure-Rejects instead to _n_
                  (default 10).
    
           **ipv6cp-max-terminate** _n_
                  Set the maximum number of IPv6CP terminate-request
                  transmissions to _n_ (default 3).
    
           **ipv6cp-restart** _n_
                  Set the IPv6CP restart interval (retransmission timeout) to
                  _n_ seconds (default 3).
    
           **kdebug** _n_
                  Enable debugging code in the kernel-level PPP driver.  The
                  argument values depend on the specific kernel driver, but
                  in general a value of 1 will enable general kernel debug
                  messages.  (Note that these messages are usually only
                  useful for debugging the kernel driver itself.)  For the
                  Linux 2.2.x kernel driver, the value is a sum of bits: 1 to
                  enable general debug messages, 2 to request that the
                  contents of received packets be printed, and 4 to request
                  that the contents of transmitted packets be printed.  On
                  most systems, messages printed by the kernel are logged by
                  syslog(1) to a file as directed in the /etc/syslog.conf
                  configuration file.
    
           **key** _keyfile_
                  (EAP-TLS) Use the file _keyfile_ as the private key file (in
                  PEM format), needed for setting up an EAP-TLS connection.
                  This option is used on the client-side in conjunction with
                  the **ca** and **cert** options.
    
           **ktune** Enables pppd to alter kernel settings as appropriate.
                  Under Linux, pppd will enable IP forwarding (i.e. set
                  /proc/sys/net/ipv4/ip_forward to 1) if the _proxyarp_ option
                  is used, and will enable the dynamic IP address option
                  (i.e. set /proc/sys/net/ipv4/ip_dynaddr to 1) in demand
                  mode if the local address changes.
    
           **lcp-echo-adaptive**
                  If this option is used with the _lcp-echo-failure_ option
                  then pppd will send LCP echo-request frames only if no
                  traffic was received from the peer since the last
                  echo-request was sent.
    
           **lcp-echo-failure** _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 connection.  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.
    
           **lcp-echo-interval** _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.
    
           **lcp-max-configure** _n_
                  Set the maximum number of LCP configure-request
                  transmissions to _n_ (default 10).
    
           **lcp-max-failure** _n_
                  Set the maximum number of LCP configure-NAKs returned
                  before starting to send configure-Rejects instead to _n_
                  (default 10).
    
           **lcp-max-terminate** _n_
                  Set the maximum number of LCP terminate-request
                  transmissions to _n_ (default 3).
    
           **lcp-restart** _n_
                  Set the LCP restart interval (retransmission timeout) to _n_
                  seconds (default 3).
    
           **lcp-rtt-file** _filename_
                  Sets the file where the round-trip time (RTT) of LCP echo-
                  request frames will be logged.
    
           **linkname** _name_
                  Sets the logical name of the link to _name_.  Pppd will
                  create a file named **ppp-**_name_**.pid** in /var/run (or /etc/ppp
                  on some systems) containing its process ID.  This can be
                  useful in determining which instance of pppd is responsible
                  for the link to a given peer system.  This is a privileged
                  option.
    
           **local** Don't use the modem control lines.  With this option, pppd
                  will ignore the state of the CD (Carrier Detect) signal
                  from the modem and will not change the state of the DTR
                  (Data Terminal Ready) signal.  This is the opposite of the
                  **modem** option.
    
           **logfd** _n_
                  Send log messages to file descriptor _n_.  Pppd will send log
                  messages to at most one file or file descriptor (as well as
                  sending the log messages to syslog), so this option and the
                  **logfile** 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.
    
           **logfile** _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.
    
           **login** Use the system password database for authenticating the
                  peer using PAP, and record the user in the system wtmp
                  file.  Note that the peer must have an entry in the
                  /etc/ppp/pap-secrets file as well as the system password
                  database to be allowed access.  See also the **enable-session**
                  option.
    
           **master_detach**
                  If multilink is enabled and this pppd process is the
                  multilink bundle master, and the link controlled by this
                  pppd process terminates, this pppd process continues to run
                  in order to maintain the bundle.  If the **master_detach**
                  option has been given, pppd will detach from its
                  controlling terminal in this situation, even if the
                  **nodetach** option has been given.
    
           **maxconnect** _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).
    
           **maxfail** _n_
                  Terminate after _n_ consecutive failed connection attempts.
                  A value of 0 means no limit.  The default value is 10.
    
           **max-tls-version** _string_
                  (EAP-TLS, or PEAP) Configures the max allowed TLS version
                  used during negotiation with a peer.  The default value for
                  this is _1.2_.  Values allowed for this option is _1.0._ , _1.1_ ,
                  _1.2_ , _1.3_.
    
           **modem** Use the modem control lines.  This option is the default.
                  With this option, pppd will wait for the CD (Carrier
                  Detect) signal from the modem to be asserted when opening
                  the serial device (unless a connect script is specified),
                  and it will drop the DTR (Data Terminal Ready) signal
                  briefly when the connection is terminated and before
                  executing the connect script.  On Ultrix, this option
                  implies hardware flow control, as for the _crtscts_ option.
                  This is the opposite of the **local** option.
    
           **mp** Enables the use of PPP multilink; this is an alias for the
                  `multilink' option.  This option is currently only
                  available under Linux.
    
           **mppe-stateful**
                  Allow MPPE to use stateful mode.  Stateless mode is still
                  attempted first.  The default is to disallow stateful mode.
    
           **mpshortseq**
                  Enables the use of short (12-bit) sequence numbers in
                  multilink headers, as opposed to 24-bit sequence numbers.
                  This option is only available under Linux, and only has any
                  effect if multilink is enabled (see the multilink option).
    
           **mrru** _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).
    
           **ms-dns** _< addr>_
                  If pppd is acting as a server for Microsoft Windows
                  clients, this option allows pppd to supply one or two DNS
                  (Domain Name Server) 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 **dns-addr**.)
    
           **ms-wins** _< addr>_
                  If pppd is acting as a server for Microsoft Windows or
                  "Samba" clients, this option allows pppd to supply one or
                  two WINS (Windows Internet Name Services) server addresses
                  to the clients.  The first instance of this option
                  specifies the primary WINS address; the second instance (if
                  given) specifies the secondary WINS address.
    
           **multilink**
                  Enables the use of the PPP multilink protocol.  If the peer
                  also supports multilink, then this link can become part of
                  a bundle between the local system and the peer.  If there
                  is an existing bundle to the peer, pppd will join this link
                  to that bundle, otherwise pppd will create a new bundle.
                  See the MULTILINK section below.  This option is currently
                  only available under Linux.
    
           **name** _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_.)
    
           **netmask** _mask_
                  Set the IPV4 network mask on the PPP interface to the given
                  _mask_ , which can be given in dotted-quad notation or as a
                  single hexadecimal number preceded by 0x.  This option is
                  not normally needed because the PPP interface is a point-
                  to-point connection, but in some specialized circumstances
                  it can be useful.
    
           **noaccomp**
                  Disable Address/Control compression in both directions
                  (send and receive).
    
           **need-peer-eap**
                  (EAP-TLS) Require the peer to verify our authentication
                  credentials.
    
           **noauth** Do not require the peer to authenticate itself.  This
                  option is privileged.
    
           **nobsdcomp**
                  Disables BSD-Compress compression; **pppd** will not request or
                  agree to compress packets using the BSD-Compress scheme.
    
           **noccp** 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.
    
           **nocrtscts**
                  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.
    
           **nocdtrcts**
                  This option is a synonym for _nocrtscts_. Either of these
                  options will disable both forms of hardware flow control.
    
           **nodefaultroute**
                  Disable the _defaultroute_ option.  The system administrator
                  who wishes to prevent users from adding a default route
                  with pppd can do so by placing this option in the
                  /etc/ppp/options file.
    
           **nodefaultroute6**
                  Disable the _defaultroute6_ option.  The system administrator
                  who wishes to prevent users from adding a default route
                  with pppd can do so by placing this option in the
                  /etc/ppp/options file.
    
           **nodeflate**
                  Disables Deflate compression; pppd will not request or
                  agree to compress packets using the Deflate scheme.
    
           **nodetach**
                  Don't detach from the controlling terminal.  Without this
                  option, if a serial device other than the terminal on the
                  standard input is specified, pppd will fork to become a
                  background process.
    
           **noendpoint**
                  Disables pppd from sending an endpoint discriminator to the
                  peer or accepting one from the peer (see the MULTILINK
                  section below).  This option should only be required if the
                  peer is buggy.
    
           **noip** Disable IPCP negotiation and IP communication.  This option
                  should only be required if the peer is buggy and gets
                  confused by requests from pppd for IPCP negotiation.
    
           **noipv6** Disable IPv6CP negotiation and IPv6 communication. This
                  option should only be required if the peer is buggy and
                  gets confused by requests from pppd for IPv6CP negotiation.
    
           **noipdefault**
                  Disables the default behaviour when no local IP address is
                  specified, which is to determine (if possible) the local IP
                  address from the hostname.  With this option, the peer will
                  have to supply the local IP address during IPCP negotiation
                  (unless it specified explicitly on the command line or in
                  an options file).
    
           **noktune**
                  Opposite of the _ktune_ option; disables pppd from changing
                  system settings.
    
           **nolock** Opposite of the _lock_ option; specifies that pppd should not
                  create a UUCP-style lock file for the serial device.  This
                  option is privileged.
    
           **nolog** Do not send log messages to a file or file descriptor.
                  This option cancels the **logfd** and **logfile** options.
    
           **nomagic**
                  Disable magic number negotiation.  With this option, pppd
                  cannot detect a looped-back line.  This option should only
                  be needed if the peer is buggy.
    
           **nomp** Disables the use of PPP multilink.  This option is
                  currently only available under Linux.
    
           **nomppe** Disables MPPE (Microsoft Point to Point Encryption).  This
                  is the default.
    
           **nomppe-40**
                  Disable 40-bit encryption with MPPE.
    
           **nomppe-128**
                  Disable 128-bit encryption with MPPE.
    
           **nomppe-stateful**
                  Disable MPPE stateful mode.  This is the default.
    
           **nompshortseq**
                  Disables the use of short (12-bit) sequence numbers in the
                  PPP multilink protocol, forcing the use of 24-bit sequence
                  numbers.  This option is currently only available under
                  Linux, and only has any effect if multilink is enabled.
    
           **nomultilink**
                  Disables the use of PPP multilink.  This option is
                  currently only available under Linux.
    
           **nopcomp**
                  Disable protocol field compression negotiation in both the
                  receive and the transmit direction.
    
           **nopersist**
                  Exit once a connection has been made and terminated.  This
                  is the default unless the _persist_ or _demand_ option has been
                  specified.
    
           **nopredictor1**
                  Do not accept or agree to Predictor-1 compression.
    
           **noproxyarp**
                  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.
    
           **noremoteip**
                  Allow pppd to operate without having an IP address for the
                  peer.  This option is only available under Linux.
                  Normally, pppd will request the peer's IP address, and if
                  the peer does not supply it, pppd will use an arbitrary
                  address in the 10.x.x.x subnet.  With this option, if the
                  peer does not supply its IP address, pppd will not ask the
                  peer for it, and will not set the destination address of
                  the ppp interface.  In this situation, the ppp interface
                  can be used for routing by creating device routes, but the
                  peer itself cannot be addressed directly for IP traffic.
    
           **nosendip**
                  Don't send our local IP address to peer during IP address
                  negotiation.
    
           **notty** Normally, pppd requires a terminal device.  With this
                  option, pppd will allocate itself a pseudo-tty master/slave
                  pair and use the slave as its terminal device.  Pppd will
                  create a child process to act as a `character shunt' to
                  transfer characters between the pseudo-tty master and its
                  standard input and output.  Thus pppd will transmit
                  characters on its standard output and receive characters on
                  its standard input even if they are not terminal devices.
                  This option increases the latency and CPU overhead of
                  transferring data over the ppp interface as all of the
                  characters sent and received must flow through the
                  character shunt process.  An explicit device name may not
                  be given if this option is used.
    
           **novj** Disable Van Jacobson style TCP/IP header compression in
                  both the transmit and the receive direction.
    
           **novjccomp**
                  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.
    
           **papcrypt**
                  Indicates that all secrets in the /etc/ppp/pap-secrets file
                  which are used for checking the identity of the peer are
                  encrypted, and thus pppd should not accept a password
                  which, before encryption, is identical to the secret from
                  the /etc/ppp/pap-secrets file.
    
           **pap-max-authreq** _n_
                  Set the maximum number of PAP authenticate-request
                  transmissions to _n_ (default 10).
    
           **pap-restart** _n_
                  Set the PAP restart interval (retransmission timeout) to _n_
                  seconds (default 3).
    
           **pap-timeout** _n_
                  Set the maximum time that pppd will wait for the peer to
                  authenticate itself with PAP to _n_ seconds (0 means no
                  limit).
    
           **pass-filter** _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 **ether** and **arp** , 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 **inbound** and **outbound** qualifiers. This
                  option is currently only available under Linux, and
                  requires that the kernel was configured to include PPP
                  filtering support (CONFIG_PPP_FILTER).
    
           **password** _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)).
    
           **persist**
                  Do not exit after a connection is terminated; instead try
                  to reopen the connection. The **maxfail** option still has an
                  effect on persistent connections.
    
           **plugin** _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 **/usr/lib/pppd/**_version_
                  directory for the plugin, where _version_ is the version
                  number of pppd (for example, 2.4.2).
    
           **predictor1**
                  Request that the peer compress frames that it sends using
                  Predictor-1 compression, and agree to compress transmitted
                  frames with Predictor-1 if requested.  This option has no
                  effect unless the kernel driver supports Predictor-1
                  compression.
    
           **privgroup** _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.
    
           **proxyarp**
                  Add an entry to this system's ARP [Address Resolution
                  Protocol] table with the IP address of the peer and the
                  Ethernet address of this system.  This will have the effect
                  of making the peer appear to other systems to be on the
                  local ethernet.
    
           **pty** _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 conjunction with the _pty_ option, the
                  child process will have pipes on its standard input and
                  output.)
    
                  It is important to note that script will be executed by
                  passing it to /bin/sh using -c, such that if script
                  contains arguments /bin/sh may attempt to interpret that,
                  and thus any arguments should be escaped to avoid shell
                  expansion.
    
           **receive-all**
                  With this option, pppd will accept all control characters
                  from the peer, including those marked in the receive
                  asyncmap.  Without this option, pppd will discard those
                  characters as specified in RFC1662.  This option should
                  only be needed if the peer is buggy.
    
           **record** _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 transfer characters between the pseudo-tty and the real
                  serial device, so it will increase the latency and CPU
                  overhead of transferring data over the ppp interface.  The
                  characters are stored in a tagged format with timestamps,
                  which can be displayed in readable form using the
                  pppdump(8) program.
    
           **remotename** _name_
                  Set the assumed name of the remote system for
                  authentication purposes to _name_.
    
           **remotenumber** _number_
                  Set the assumed telephone number of the remote system for
                  authentication purposes to _number_.
    
           **refuse-chap**
                  With this option, pppd will not agree to authenticate
                  itself to the peer using CHAP.
    
           **refuse-mschap**
                  With this option, pppd will not agree to authenticate
                  itself to the peer using MS-CHAP.
    
           **refuse-mschap-v2**
                  With this option, pppd will not agree to authenticate
                  itself to the peer using MS-CHAPv2.
    
           **refuse-eap**
                  With this option, pppd will not agree to authenticate
                  itself to the peer using EAP.
    
           **refuse-pap**
                  With this option, pppd will not agree to authenticate
                  itself to the peer using PAP.
    
           **require-chap**
                  Require the peer to authenticate itself using CHAP
                  [Challenge Handshake Authentication Protocol]
                  authentication.
    
           **require-mppe**
                  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.
    
           **require-mppe-40**
                  Require the use of MPPE, with 40-bit encryption.
    
           **require-mppe-128**
                  Require the use of MPPE, with 128-bit encryption.
    
           **require-mschap**
                  Require the peer to authenticate itself using MS-CHAP
                  [Microsoft Challenge Handshake Authentication Protocol]
                  authentication.
    
           **require-mschap-v2**
                  Require the peer to authenticate itself using MS-CHAPv2
                  [Microsoft Challenge Handshake Authentication Protocol,
                  Version 2] authentication.
    
           **require-eap**
                  Require the peer to authenticate itself using EAP
                  [Extensible Authentication Protocol] authentication.
    
           **require-pap**
                  Require the peer to authenticate itself using PAP [Password
                  Authentication Protocol] authentication.
    
           **set** _name_ =_value_
                  Set an environment variable for scripts that are invoked by
                  pppd.  When set by a privileged source, the variable
                  specified by _name_ cannot be changed by options contained in
                  an unprivileged source.  See also the _unset_ option and the
                  environment described in _SCRIPTS_.
    
           **show-password**
                  When logging the contents of PAP packets, this option
                  causes pppd to show the password string in the log message.
    
           **silent** With this option, pppd will not transmit LCP packets to
                  initiate a connection until a valid LCP packet is received
                  from the peer (as for the `passive' option with ancient
                  versions of pppd).
    
           **srp-interval** _n_
                  If this parameter is given and pppd uses EAP SRP-SHA1 to
                  authenticate the peer (i.e., is the server), then pppd will
                  use the optional lightweight SRP rechallenge mechanism at
                  intervals of _n_ seconds.  This option is faster than
                  **eap-interval** reauthentication because it uses a hash-based
                  mechanism and does not derive a new session key.
    
           **srp-pn-secret** _string_
                  Set the long-term pseudonym-generating secret for the
                  server.  This value is optional and if set, needs to be
                  known at the server (authenticator) side only, and should
                  be different for each server (or poll of identical
                  servers).  It is used along with the current date to
                  generate a key to encrypt and decrypt the client's identity
                  contained in the pseudonym.
    
           **srp-use-pseudonym**
                  When operating as an EAP SRP-SHA1 client, attempt to use
                  the pseudonym stored in ~/.ppp_pseudonym first as the
                  identity, and save in this file any pseudonym offered by
                  the peer during authentication.
    
           **stop-bits** _n_
                  Set the number of stop bits for the serial port. Valid
                  values are 1 or 2.  The default value is 1.
    
           **sync** Use synchronous HDLC serial encoding instead of
                  asynchronous.  The device used by pppd with this option
                  must have sync support.  Currently supports Microgate
                  SyncLink adapters under Linux and FreeBSD 2.2.8 and later.
    
           **tls-verify-method** _string_
                  (EAP-TLS, or PEAP) Match the value specified for _remotename_
                  to that that of the X509 certificates subject name, common
                  name, or suffix of the common name.  Respective values
                  allowed for this option is: _none_ , _subject_ , _name_ , or _suffix_.
                  The default value for this option is _name_.
    
           **tls-verify-key-usage**
                  (EAP-TLS, or PEAP) Enables examination of peer
                  certificate's purpose, and extended key usage attributes.
    
           **unit** _num_
                  Sets the ppp unit number (for a ppp0 or ppp1 etc interface
                  name) for outbound connections.  If the unit is already in
                  use a dynamically allocated number will be used.
    
           **ifname** _string_
                  Set the ppp interface name for outbound connections.  If
                  the interface name is already in use, or if the name cannot
                  be used for any other reason, pppd will terminate.
    
           **unset** _name_
                  Remove a variable from the environment variable for scripts
                  that are invoked by pppd.  When specified by a privileged
                  source, the variable _name_ cannot be set by options
                  contained in an unprivileged source.  See also the _set_
                  option and the environment described in _SCRIPTS_.
    
           **updetach**
                  With this option, pppd will detach from its controlling
                  terminal once it has successfully established the ppp
                  connection (to the point where the first network control
                  protocol, usually the IP control protocol, has come up).
    
           **up_sdnotify**
                  Use this option to run pppd in systemd service units of
                  Type=notify (**up_sdnotify** implies **nodetach**).  When
                  **up_sdnotify** is enabled, pppd will notify systemd once it
                  has successfully established the ppp connection (to the
                  point where the first network control protocl, usually the
                  IP control protocol, has come up). This option is only
                  availble when pppd is compiled with systemd support.
    
           **usehostname**
                  Enforce the use of the hostname (with domain name appended,
                  if given) as the name of the local system for
                  authentication purposes (overrides the _name_ option).  This
                  option is not normally needed since the _name_ option is
                  privileged.
    
           **usepeerdns**
                  Ask the peer for up to 2 DNS server addresses.  The
                  addresses supplied by the peer (if any) are passed to the
                  /etc/ppp/ip-up script in the environment variables DNS1 and
                  DNS2, and the environment 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 (unless the
                  _noresolvconf_ option is given).
    
           **usepeerwins**
                  Ask the peer for up to 2 WINS server addresses.  The
                  addresses supplied by the peer (if any) are passed to the
                  /etc/ppp/ip-up script in the environment variables WINS1
                  and WINS2, and the environment variable USEPEERWINS will be
                  set to 1.
    
           Please note that some modems (like the Huawei E220) requires this
           option in order to avoid a race condition that results in the
           incorrect DNS servers being assigned.
    
           **noresolvconf**
                  Do not create the /etc/ppp/resolv.conf file.
    
           **user** _name_
                  Sets the name used for authenticating the local system to
                  the peer to _name_.
    
           **vj-max-slots** _n_
                  Sets the number of connection slots to be used by the Van
                  Jacobson TCP/IP header compression and decompression code
                  to _n_ , which must be between 2 and 16 (inclusive).
    
           **welcome** _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.
    
           **xonxoff**
                  Use software flow control (i.e. XON/XOFF) to control the
                  flow of data on the serial port.
    


## PPPOE OPTIONS



           To establish PPP link over Ethernet (PPPoE) it is needed to load
           pppd's **plugin pppoe.so** and then specify option **nic-**_interface_
           instead of modem options _ttyname_ and _speed_.  Recognized pppd's
           PPPoE options are:
    
           **nic-**_interface_
                  Use the ethernet device _interface_ to communicate with the
                  peer.  For example, establishing PPPoE link on _eth0_
                  interface is done by specifying ppp'd option **nic-eth0**.
                  Prefix **nic-** for this option may be avoided if interface
                  name is unambiguous and does not look like any other pppd's
                  option.
    
           **pppoe-service** _name_
                  Connect to specified PPPoE service name. For backward
                  compatibility also **rp_pppoe_service** option name is
                  supported.
    
           **pppoe-ac** _name_
                  Connect to specified PPPoE access concentrator name. For
                  backward compatibility also **rp_pppoe_ac** option name is
                  supported.
    
           **pppoe-sess** _sessid_**:**_macaddr_
                  Attach to existing PPPoE session. For backward
                  compatibility also **rp_pppoe_sess** option name is supported.
    
           **pppoe-verbose** _n_
                  Be verbose about discovered access concentrators. When set
                  to 2 or bigger value then dump also discovery packets. For
                  backward compatibility also **rp_pppoe_verbose** option name is
                  supported.
    
           **pppoe-mac** _macaddr_
                  Connect to specified MAC address.
    
           **pppoe-host-uniq** _string_
                  Set the PPPoE Host-Uniq tag to the supplied hex string.  By
                  default PPPoE Host-Uniq tag is set to the pppd's process
                  PID.  For backward compatibility this option may be
                  specified without **pppoe-** prefix.
    
           **pppoe-padi-timeout** _n_
                  Initial timeout for discovery packets in seconds (default
                  5).
    
           **pppoe-padi-attempts** _n_
                  Number of discovery attempts (default 3).
    


## 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
           whitespace.  Whitespace can be included in a word by enclosing the
           word in double-quotes (").  A backslash (\) quotes the following
           character.  A hash (#) starts a comment, which continues until the
           end of the line.  There is no restriction on using the _file_ or
           _call_ options within an options file.
    


## SECURITY



           _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 administrator, 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 connection.  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 internet 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 permission to access.
           Otherwise pppd uses the invoking user's real UID when opening the
           device.
    


## AUTHENTICATION



           Authentication is the process whereby one peer convinces the other
           of its identity.  This involves the first peer sending its name to
           the other, together with some kind of secret information which
           could only come from the genuine authorized user of that name.  In
           such an exchange, we will call the first peer the "client" and the
           other the "server".  The client has a name by which it identifies
           itself to the server, and the server also has a name by which it
           identifies itself to the client.  Generally the genuine client
           shares some secret (or password) with the server, and
           authenticates itself by proving that it knows that secret.  Very
           often, the names used for authentication correspond to the
           internet hostnames of the peers, but this is not essential.
    
           At present, pppd supports three authentication protocols: the
           Password Authentication Protocol (PAP), Challenge Handshake
           Authentication Protocol (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.
           EAP supports CHAP-style authentication, and also includes the
           SRP-SHA1 mechanism, which is resistant to dictionary-based attacks
           and does not require a cleartext password on the server side.
    
           The PPP protocol, being symmetrical, allows both peers to require
           the other to authenticate itself.  In that case, two separate and
           independent authentication exchanges will occur.  The two
           exchanges could use different authentication protocols, and in
           principle, different names could be used in the two exchanges.
    
           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, and EAP MD5-Challenge, and
           /etc/ppp/srp-secrets for EAP SRP-SHA1).  All 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
           acceptable IP addresses for that client.  If there are only 3
           words on the line, or if the first word is "-", then all IP
           addresses are disallowed.  To allow any address, use "*".  A word
           starting with "!"  indicates that the specified address is _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 network 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.  (For EAP
           SRP-SHA1, see the srp-entry(8) utility for generating proper
           validator entries to be used in the "secret" field.)
    
           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
           password are also checked against the system password database.
           Thus, the system administrator can set up the pap-secrets file to
           allow PPP access only to certain users, and to restrict the set of
           IP addresses that each user can use.  Typically, when using the
           _login_ option, the secret in /etc/ppp/pap-secrets would be "",
           which will match any password supplied by the peer.  This avoids
           the need to have the same secret in two places.
    
           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
           terminated the link (by closing LCP).  If IPCP negotiates an
           unacceptable IP address for the remote host, IPCP will be closed.
           IP packets can only be sent or received when IPCP is open.
    
           In some cases it is desirable to allow some hosts which can't
           authenticate themselves to connect and use one of a restricted set
           of IP addresses, even when the local host generally requires
           authentication.  If the peer refuses to authenticate itself when
           requested, pppd takes that as equivalent to authenticating with
           PAP using the empty string for the username and password.  Thus,
           by adding a line to the pap-secrets file which specifies the empty
           string for the client and password, it is possible to allow
           restricted access to hosts which refuse to authenticate
           themselves.
    


## ROUTING



           When IPCP negotiation is completed successfully, pppd will inform
           the kernel of the local and remote IP addresses for the ppp
           interface.  This is sufficient to create a host route to the
           remote end of the link, which will enable the peers to exchange IP
           packets.  Communication with other machines generally requires
           further modification to routing tables and/or ARP (Address
           Resolution Protocol) tables.  In most cases the _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 communicate 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 negotiated addresses.  This may
           disrupt existing connections, and the use of demand dialling with
           peers that do dynamic IP address assignment is not recommended.
    


## MULTILINK



           Multilink PPP provides the capability to combine two or more PPP
           links between a pair of machines into a single `bundle', which
           appears as a single virtual PPP link which has the combined
           bandwidth of the individual links.  Currently, multilink PPP is
           only supported under Linux.
    
           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 some circumstances the peer may send no endpoint discriminator
           or a non-unique value.  The 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/pppd2.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.
    
           If the first link terminates (for example, because of a hangup or
           a received LCP terminate-request) the bundle is not destroyed
           unless there are no other links remaining in the bundle.  Rather
           than exiting, the first pppd keeps running after its link
           terminates, until all the links in the bundle have terminated.  If
           the first pppd receives a SIGTERM or SIGINT signal, it will
           destroy the bundle and send a SIGHUP to the pppd processes for
           each of the links in the bundle.  If the first pppd receives a
           SIGHUP signal, it will terminate its link but not the bundle.
    
           Note: demand mode is not currently supported with multilink.
    


## EXAMPLES



           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
           contains 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, /etc/ppp/chap-secrets, or
           /etc/ppp/srp-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" that 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
    
           (See srp-entry(8) for a means to generate the server's entry when
           SRP-SHA1 is in use.)  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 transparent; 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 LOG_DAEMON.
           (This can be overridden by recompiling pppd with the macro LOG_PPP
           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 destination(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 packets.  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.
    


## EXIT STATUS



           The exit status of pppd is set to indicate whether any error was
           detected, or the reason for the link being terminated.  The values
           used are:
    
           **0** Pppd has detached, or otherwise the connection was
                  successfully established and terminated at the peer's
                  request.
    
           **1** An immediately fatal error of some kind occurred, such as
                  an essential system call failing, or running out of virtual
                  memory.
    
           **2** An error was detected in processing the options given, such
                  as two mutually exclusive options being used.
    
           **3** Pppd is not setuid-root and the invoking user is not root.
    
           **4** The kernel does not support PPP, for example, the PPP
                  kernel driver is not included or cannot be loaded.
    
           **5** Pppd terminated because it was sent a SIGINT, SIGTERM or
                  SIGHUP signal.
    
           **6** The serial port could not be locked.
    
           **7** The serial port could not be opened.
    
           **8** The connect script failed (returned a non-zero exit
                  status).
    
           **9** The command specified as the argument to the _pty_ option
                  could not be run.
    
           **10** The PPP negotiation failed, that is, it didn't reach the
                  point where at least one network protocol (e.g. IP) was
                  running.
    
           **11** The peer system failed (or refused) to authenticate itself.
    
           **12** The link was established successfully and terminated
                  because it was idle.
    
           **13** The link was established successfully and terminated
                  because the connect time limit was reached.
    
           **14** Callback was negotiated and an incoming call should arrive
                  shortly.
    
           **15** The link was terminated because the peer is not responding
                  to echo requests.
    
           **16** The link was terminated by the modem hanging up.
    
           **17** The PPP negotiation failed because serial loopback was
                  detected.
    
           **18** The init script failed (returned a non-zero exit status).
    
           **19** We failed to authenticate ourselves to the peer.
    


## SCRIPTS



           Pppd invokes scripts at various stages in its processing which can
           be used to perform site-specific ancillary processing.  These
           scripts are usually shell scripts, but could be executable code
           files instead.  Pppd does not wait for the scripts to finish
           (except for the net-init, net-pre-up and ip-pre-up scripts).  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:
    
           **DEVICE** The name of the serial tty device being used.
    
           **IFNAME** The name of the network interface being used.
    
           **IPLOCAL**
                  The IP address for the local end of the link.  This is only
                  set when IPCP has come up.
    
           **IPREMOTE**
                  The IP address for the remote end of the link.  This is
                  only set when IPCP has come up.
    
           **LLLOCAL**
                  The Link-Local IPv6 address for the local end of the link.
                  This is only set when IPV6CP has come up.
    
           **LLREMOTE**
                  The Link-Local IPv6 address for the remote end of the link.
                  This is only set when IPV6CP has come up.
    
           **PEERNAME**
                  The authenticated name of the peer.  This is only set if
                  the peer authenticates itself.
    
           **REMOTENUMBER**
                  The remote's number as provided to pppd by the remotenumber
                  option.  The meaning of this varies based on the type of
                  connection, xl2tpd for example can either provide the
                  dialing number AVP or the remote's IP address.  pppoe-
                  server typically provides the MAC address.
    
           **SPEED** The baud rate of the tty device.
    
           **ORIG_UID**
                  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:
    
           **CONNECT_TIME**
                  The number of seconds from when the PPP negotiation started
                  until the connection was terminated.
    
           **BYTES_SENT**
                  The number of bytes sent (at the level of the serial port)
                  during the connection.
    
           **BYTES_RCVD**
                  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.
    
           **CALL_FILE**
                  The value of the _call_ option.
    
           **DNS1** If the peer supplies DNS server addresses, this variable is
                  set to the first DNS server address supplied (whether or
                  not the usepeerdns option was given).
    
           **DNS2** If the peer supplies DNS server addresses, this variable is
                  set to the second DNS server address supplied (whether or
                  not the usepeerdns option was given).
    
           **WINS1** If the peer supplies WINS server addresses, this variable
                  is set to the first WINS server address supplied.
    
           **WINS2** If the peer supplies WINS server addresses, this variable
                  is set to the second WINS server address supplied.
    
           **ACNAME** If the pppoe plugin is used to establish a connection to an
                  access concentrator (AC), this variable is set to the name
                  of the AC, as supplied by the AC.
    
           Pppd invokes the following scripts, if they exist.  It is not an
           error if they don't exist.
    
           **/etc/ppp/auth-up**
                  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 ipparam_
    
                  Note that this script is not executed if the peer doesn't
                  authenticate itself, for example when the _noauth_ option is
                  used.
    
           **/etc/ppp/auth-down**
                  A program or script which is executed when the link goes
                  down, if /etc/ppp/auth-up was previously executed.  It is
                  executed in the same manner with the same parameters as
                  /etc/ppp/auth-up.
    
           **/etc/ppp/ip-pre-up**
                  A program or script which is executed just before the ppp
                  network interface is brought up.  It is executed with the
                  same parameters as the ip-up script (below).  At this point
                  the interface exists and has IP addresses assigned but is
                  still down.  This can be used to add firewall rules before
                  any IP traffic can pass through the interface.  Pppd will
                  wait for this script to finish before bringing the
                  interface up, so this script should run quickly.
    
           WARNING:  Please note that on systems where a single interface
           carries multiple protocols (Linux) ip-pre-up is NOT actually
           guaranteed to execute prior to the interface moving into an up
           state, although IP information won't be known you should consider
           using net-pre-up instead, alternatively, disable other NCPs such
           that IPv4 is the only negotiated protocol - which will also result
           in a guarantee that ip-pre-up is called prior to the interface
           going into an UP state.
    
           **/etc/ppp/ip-up**
                  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_
    
           **/etc/ppp/ip-down**
                  A program or script which is executed when the link is no
                  longer available for sending and receiving IP packets.
                  This script can be used for undoing the effects of the
                  /etc/ppp/ip-up and /etc/ppp/ip-pre-up scripts.  It is
                  invoked in the same manner and with the same parameters as
                  the ip-up script.
    
           **/etc/ppp/ipv6-up**
                  Like /etc/ppp/ip-up, except that it is executed when the
                  link is available for sending and receiving IPv6 packets.
                  It is executed with the parameters
    
                  _interface-name tty-device speed local-link-local-address_
                  _remote-link-local-address ipparam_
    
           **/etc/ppp/ipv6-down**
                  Similar to /etc/ppp/ip-down, but it is executed when IPv6
                  packets can no longer be transmitted on the link. It is
                  executed with the same parameters as the ipv6-up script.
    
           **/etc/ppp/net-init**
                  This script will be executed the moment the ppp unit number
                  is known.  This script will be waited for and should not
                  cause significant delays.  This can be used to update book-
                  keeping type systems external to ppp and provides the only
                  guaranteed point where a script can be executed knowing the
                  ppp unit number prior to LCP being initiated.  It is
                  executed with the parameters
    
                  _interface-name tty-device speed ipparam_
    
           **/etc/ppp/net-pre-up**
                  This script will be executed just prior to NCP negotiations
                  initiating, and is guaranteed to be executed whilst the
                  interface (Linux) and/or sub-interfaces (Solaris) as the
                  case may be is/are still down.  ppp will block waiting for
                  this script to complete, and the interface may be safely
                  renamed in this script (using for example "ip li set dev $1
                  name ppp-foobar".  The parameters are the same as for
                  net-init.
    
           **/etc/ppp/net-down**
                  This script will be executed just prior to ppp terminating
                  and will not be waited for.  The parameters are the same as
                  for net-init.
    
           **/var/run/ppp** _n_**.pid**(BSD or Linux), **/etc/ppp/ppp** _n_**.pid**(others)
                  Process-ID for pppd process on ppp interface unit _n_.
    
           **/var/run/ppp-**_name_**.pid**(BSD or Linux),
                  **/etc/ppp/ppp-**_name_**.pid**(others) Process-ID for pppd process
                  for logical link _name_ (see the _linkname_ option).
    
           **/var/run/pppd2.tdb**
                  Database containing information about pppd processes,
                  interfaces and links, used for matching links to bundles in
                  multilink operation.  May be examined by external programs
                  to obtain information about running pppd instances, the
                  interfaces and devices they are using, IP address
                  assignments, etc.  **/etc/ppp/pap-secrets** 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.
    
           **/etc/ppp/chap-secrets**
                  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.
    
           **/etc/ppp/srp-secrets**
                  Names, secrets, and IP addresses for EAP 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.
    
           **~/.ppp_pseudonym**
                  Saved client-side SRP-SHA1 pseudonym.  See the
                  _srp-use-pseudonym_ option for details.
    
           **/etc/ppp/options**
                  System default options for pppd, read before user default
                  options or command-line options.
    
           **~/.ppprc**
                  User default options, read before /etc/ppp/options._ttyname_.
    
           **/etc/ppp/options.**_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.
    
           **/etc/ppp/peers**
                  A directory containing options files which may contain
                  privileged options, even if pppd was invoked by a user
                  other than root.  The system administrator can create
                  options files in this directory to permit non-privileged
                  users to dial out without requiring the peer to
                  authenticate, but only to certain trusted peers.
    


## NOTES



           Some limited degree of control can be exercised over a running
           pppd process by sending it a signal from the list below.
    
           **SIGINT, SIGTERM**
                  These signals cause pppd to terminate the link (by closing
                  LCP), restore the serial device settings, and exit.  If a
                  connector or disconnector process is currently running,
                  pppd will send the same signal to its process group, so as
                  to terminate the connector or disconnector process.
    
           **SIGHUP** 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.  If a connector or disconnector process is
                  running, pppd will send the same signal to its process
                  group.
    
           **SIGUSR1**
                  This signal toggles the state of the _debug_ option.
    
           **SIGUSR2**
                  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.)
    


* * *