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RedHat 9 (Linux i386) - man page for pppd (redhat section 8)

PPPD(8) 			     System Manager's Manual				  PPPD(8)

NAME
       pppd - Point to Point Protocol daemon

SYNOPSIS
       pppd [ tty_name ] [ speed ] [ options ]

DESCRIPTION
       The Point-to-Point Protocol (PPP) provides a method for transmitting datagrams over serial
       point-to-point links.  PPP is composed of three parts: a method	for  encapsulating  data-
       grams  over  serial links, an extensible Link Control Protocol (LCP), and a family of Net-
       work Control Protocols (NCP) for establishing and configuring different network-layer pro-
       tocols.

       The  encapsulation  scheme  is  provided  by driver code in the kernel.	Pppd provides the
       basic LCP, authentication support, and an NCP for establishing and configuring the  Inter-
       net Protocol (IP) (called the IP Control Protocol, IPCP).

FREQUENTLY USED OPTIONS
       <tty_name>
	      Communicate  over  the named device.  The string "/dev/" is prepended if necessary.
	      If no device name is given, or if the name of the terminal connected to  the  stan-
	      dard  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>
	      Set  the	baud  rate  to <speed> (a decimal number).  On systems such as 4.4BSD and
	      NetBSD, any speed can be specified.  Other systems (e.g. SunOS) allow only  a  lim-
	      ited set of speeds.

       asyncmap <map>
	      Set  the async character map to <map>.  This map describes which control characters
	      cannot be successfully received over the serial line.  Pppd will ask  the  peer  to
	      send  these  characters  as a 2-byte escape sequence.  The argument is a 32 bit hex
	      number with each bit representing a character to escape.	Bit 0  (00000001)  repre-
	      sents  the  character  0x00; bit 31 (80000000) represents the character 0x1f or ^_.
	      If multiple asyncmap options are given,  the  values  are  ORed  together.   If  no
	      asyncmap option is given, no async character map will be negotiated for the receive
	      direction; the peer should then escape all control characters.  To escape transmit-
	      ted 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 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
	      Use  the executable or shell command specified by script to set up the serial line.
	      This script would typically use the chat(8) program to dial the modem and start the
	      remote  ppp  session.   A  value for this option from a privileged source cannot be
	      overridden by a non-privileged user.

       crtscts
	      Use hardware flow control (i.e. RTS/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 unidirectional  flow  control.  The  serial
	      port  will  suspend  transmission when requested by the modem (via CTS) but will be
	      unable to request the modem stop sending to the computer.  This  mode  retains  the
	      ability to use DTR as a modem control line.

       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.

       disconnect script
	      Run the executable or shell command specified by script after pppd  has  terminated
	      the  link.  This script could, for example, issue commands to the modem to cause it
	      to hang up if hardware modem control signals were not  available.   The  disconnect
	      script is not run if the modem has already hung up.  A value for this option from a
	      privileged source cannot be overridden by a non-privileged user.

       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
	      Run  the	executable  or shell command specified by script 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.

       mru n  Set the MRU [Maximum Receive Unit] value to n. Pppd will ask the peer to send pack-
	      ets of no more than n bytes.  The minimum MRU value is 128.  The default MRU  value
	      is  1500.  A value of 296 is recommended for slow links (40 bytes for TCP/IP header
	      + 256 bytes of data).  (Note that for IPv6 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 IPv6 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 <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 (see above).  On systems which supports a unique persistent  id,
	      such  as EUI-48 derived from the Ethernet MAC address, ipv6cp-use-persistent option
	      can be used to replace the ipv6 <local>,<remote> option. Otherwise  the  identifier
	      is 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 con-
	      junction with the idle option if there are packets being sent or received regularly
	      over the link (for example, routing information packets) which would otherwise pre-
	      vent 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  Net-
	      BSD,  and  then  only  if  both  the  kernel and pppd were compiled with PPP_FILTER
	      defined.

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

       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  compres-
	      sion  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.

       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 con-
	      trol. The sacrifice is that this flow control mode does not permit using DTR  as	a
	      modem control line.

       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).

       connect-delay n
	      Wait for up n milliseconds after the connect script finishes for a valid PPP packet
	      from  the  peer.	 At  the end of this time, or when a valid PPP packet is received
	      from the peer, pppd will commence negotiation by sending its first LCP packet.  The
	      default  value is 1000 (1 second).  This wait period only applies if the connect or
	      pty option is used.

       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 pack-
	      ets are logged through syslog with facility daemon and level debug.  This  informa-
	      tion  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.

       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 com-
	      pression in the corresponding direction.	Use nodeflate or  deflate  0  to  disable
	      Deflate  compression entirely.  (Note: pppd requests Deflate compression in prefer-
	      ence 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 must be specified by the user on the command line or
	      in an options file.  Pppd will initially configure the interface and enable it  for
	      IP  traffic  without  connecting to the peer.  When traffic is available, 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 conjuction 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  out-
	      put 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.

       endpoint <epdisc>
	      Sets the endpoint discriminator sent by the local machine to the peer during multi-
	      link 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-dec-
	      imal 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.

       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  termi-
	      nates.   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.

       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 con-
	      figure-Rejects instead to n (default 10).

       ipcp-max-terminate n
	      Set the maximum number of IPCP terminate-request transmissions to n (default 3).

       ipcp-restart n
	      Set the IPCP restart interval (retransmission timeout) to n seconds (default 3).

       ipparam string
	      Provides	an  extra  parameter to the ip-up and ip-down scripts.	If this option is
	      given, the string supplied is given as the 6th parameter to those scripts.

       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).

       ipx    Enable  the IPXCP and IPX protocols.  This option is presently only supported under
	      Linux, and only if your kernel has been configured to include IPX support.

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

       ipx-node n:m
	      Set the IPX node numbers. The two node numbers are separated from each other with a
	      colon character. The first number n is the local node number. The second	number	m
	      is  the  peer's  node  number. Each node number is a hexadecimal number, at most 10
	      digits long. The node numbers on the ipx-network must be unique. There is no  valid
	      default.	If  this  option is not specified then the node numbers are obtained from
	      the peer.

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

       ipx-routing n
	      Set  the	routing protocol to be received by this option. More than one instance of
	      ipx-routing may be specified. The 'none' option (0) may be specified  as	the  only
	      instance	of  ipx-routing.  The  values may be 0 for NONE, 2 for RIP/SAP, and 4 for
	      NLSP.

       ipxcp-accept-local
	      Accept the peer's NAK for the node number specified in the ipx-node  option.  If	a
	      node number was specified, and non-zero, the default is to insist that the value be
	      used. If you include this option then you will permit  the  peer	to  override  the
	      entry of the node number.

       ipxcp-accept-network
	      Accept  the  peer's NAK for the network number specified in the ipx-network option.
	      If a network number was specified, and non-zero, the default is to insist that  the
	      value be used. If you include this option then you will permit the peer to override
	      the entry of the node number.

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

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

       ipxcp-max-failure n
	      Set  the maximum number of IPXCP NAK frames which the local system will send before
	      it rejects the options. The default value is 3.

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

       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 ker-
	      nel  debug  messages.  (Note that these messages are usually only useful for debug-
	      ging 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.

       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-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  termi-
	      nate 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 con-
	      figure-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).

       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.

       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.

       maxconnect n
	      Terminate the connection when it has been available for network traffic for n  sec-
	      onds (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.

       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.

       mp     Enables  the  use  of  PPP  multilink; this is an alias for the `multilink' option.
	      This option is currently only available under Linux.

       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 indi-
	      vidual 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  multi-
	      link,  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	authenti-
	      cating 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 n
	      Set  the	interface  netmask to n, a 32 bit netmask in "decimal dot" notation (e.g.
	      255.255.255.0).  If this option is given, the value  specified  is  ORed	with  the
	      default  netmask.   The default netmask is chosen based on the negotiated remote IP
	      address; it is the appropriate network mask for the class of the remote IP address,
	      ORed  with the netmasks for any non point-to-point network interfaces in the system
	      which are on the same network.  (Note: on some  platforms,  pppd	will  always  use
	      255.255.255.255 for the netmask, if that is the only appropriate value for a point-
	      to-point interface.)

       noaccomp
	      Disable Address/Control compression in both directions (send and receive).

       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 pack-
	      ets 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 nego-
	      tiation.

       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  creating  default routes 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).

       noipx  Disable  the  IPXCP  and IPX protocols.  This option should only be required if the
	      peer is buggy and gets confused by requests from pppd for IPXCP negotiation.

       noktune
	      Opposite of the ktune option; disables pppd from changing system settings.

       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.

       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  avail-
	      able 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.

       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  charac-
	      ters  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 stan-
	      dard  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  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 sin-
	      gle-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  cur-
	      rently  only available under NetBSD, and then only if both the kernel and pppd were
	      compiled with PPP_FILTER defined.

       persist
	      Do not exit after a connection is terminated; instead try to reopen the connection.

       plugin filename
	      Load the shared library object file filename as a plugin.   This	is  a  privileged
	      option.

       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  spe-
	      cific  terminal  device.	 Pppd will allocate itself a pseudo-tty master/slave pair
	      and use the slave as its terminal device.  The  script  will  be	run  in  a  child
	      process  with  the pseudo-tty master as its standard input and output.  An explicit
	      device name may not be given if this option is used.  (Note: if the  record  option
	      is used in conjuction with the pty option, the child process will have pipes on its
	      standard input and output.)

       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 permis-
	      sions.   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.

       refuse-chap
	      With  this  option,  pppd  will  not agree to authenticate itself to the peer using
	      CHAP.

       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 Authentica-
	      tion Protocol] authentication.

       require-pap
	      Require  the  peer to authenticate itself using PAP [Password Authentication Proto-
	      col] authentication.

       show-password
	      When logging the contents of PAP packets, this option causes pppd to show the pass-
	      word 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).

       sync   Use  synchronous	HDLC serial encoding instead of asynchronous.  The device used by
	      pppd with this option must have sync support.  Currently	supports  Microgate  Syn-
	      cLink adapters under Linux and FreeBSD 2.2.8 and later.

       updetach
	      With  this  option, pppd will detach from its controlling terminal once it has suc-
	      cessfully established the ppp connection (to the point where the first network con-
	      trol protocol, usually the IP control protocol, has come up).

       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.   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.

       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 (inclu-
	      sive).

       welcome script
	      Run the executable or shell command specified by script before initiating PPP nego-
	      tiation,	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.

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  pro-
       cessing	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 secu-
       rity 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 configura-
       tions; 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  con-
       nection.   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 privi-
       leges   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 inter-
       net hostnames of the peers, but this is not essential.

       At present, pppd supports two authentication protocols: the Password Authentication Proto-
       col  (PAP)  and	the Challenge Handshake Authentication Protocol (CHAP).  PAP involves the
       client sending its name and a cleartext password to the server to authenticate itself.  In
       contrast,  the server initiates the CHAP authentication exchange by sending a challenge to
       the client (the challenge packet includes the server's name).   The  client  must  respond
       with  a	response which includes its name plus a hash value derived from the shared secret
       and the challenge, in order to prove that it knows the secret.

       The PPP protocol, being symmetrical, allows both peers to require the other  to	authenti-
       cate  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).  Both secrets  files  have  the  same  format.   The
       secrets	files  can contain secrets for pppd to use in authenticating itself to other sys-
       tems, 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 particu-
       lar  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  speci-
       fied 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  char-
       acters  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.

       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  sec-
       ond  field.   Pppd  will  know  the name of the peer if CHAP authentication is being used,
       because the peer will have sent it in the challenge packet.   However,  if  PAP	is  being
       used,  pppd will have to determine the peer's name from the options specified by the user.
       The user can specify the peer's name directly with the 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 authenti-
       cating 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 gener-
       ally 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.  Commu-
       nication  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  loop-
       back  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 end-
       point option.

       In circumstances the peer may send no endpoint discriminator or a non-unique  value.   The
       optional bundle option adds an extra string which is added to the peer's endpoint discrim-
       inator and authenticated identity when matching up links to be joined together in  a  bun-
       dle.   The  bundle  option can also be used to allow the establishment of multiple bundles
       between the local system and the peer.  Pppd uses a TDB database in  /var/run/pppd.tdb  to
       match up links.

       Assuming  that  multilink  is enabled and the peer is willing to negotiate multilink, then
       when pppd is invoked to bring up the first link to the peer, it will detect that no  other
       link is connected to the peer and create a new bundle, that is, another ppp network inter-
       face unit.  When another pppd is invoked to bring up another link to  the  peer,  it  will
       detect  the  existing bundle and join its link to it.  Currently, if the first pppd termi-
       nates (for example, because of a hangup or a received signal) the bundle is destroyed.

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  some-
       thing 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	or  /etc/ppp/chap-secrets
       (depending  on  which  authentication  method the PPP implementation on the user's machine
       supports), so that the user's machine can authenticate itself.  For example, if Joe has	a
       machine	called	"joespc" which is to be allowed to dial in to the machine called "server"
       and use the IP address joespc.my.net, you would add an entry like  this	to  /etc/ppp/pap-
       secrets or /etc/ppp/chap-secrets:

	      joespc	server	  "joe's secret" joespc.my.net

       Alternatively,  you can create a username called (for example) "ppp", whose login shell is
       pppd and whose home directory is /etc/ppp.  Options to be used when pppd is run	this  way
       can be put in /etc/ppp/.ppprc.

       If  your  serial  connection is any more complicated than a piece of wire, you may need to
       arrange for some control characters to be escaped.  In particular, it is often  useful  to
       escape  XON  (^Q) and XOFF (^S), using asyncmap a0000.  If the path includes a telnet, you
       probably should escape ^] as well (asyncmap 200a0000).  If the path  includes  an  rlogin,
       you  will  need to use the escape ff option on the end which is running the rlogin client,
       since many rlogin implementations are not  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 overriden
       by recompiling pppd with the macro LOG_PPP defined as the desired facility.)  In order  to
       see  the  error	and  debug  messages, you will need to edit your /etc/syslog.conf file to
       direct the messages to the desired output device or file.

       The debug option causes the contents of all control packets sent or received to be logged,
       that  is,  all  LCP, PAP, CHAP or IPCP packets.	This can be useful if the PPP negotiation
       does not succeed 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 exclu-
	      sive 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.  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 con-
       tents 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.

       PEERNAME
	      The  authenticated  name	of  the peer.  This is only set if the peer authenticates
	      itself.

       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  sta-
       tistics 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  connec-
	      tion.

       LINKNAME
	      The logical name of the link, set with the linkname option.

       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  authen-
	      ticates itself.  It is executed with the parameters

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

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

       /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 parame-
	      ters as /etc/ppp/auth-up.

       /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 parame-
	      ters

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

	      interface-name  tty-device  speed network-number local-IPX-node-address remote-IPX-
	      node-address  local-IPX-routing-protocol	 remote-IPX-routing-protocol   local-IPX-
	      router-name remote-IPX-router-name ipparam pppd-pid

	      The  local-IPX-routing-protocol and remote-IPX-routing-protocol field may be one of
	      the following:

	      NONE	to indicate that there is no routing protocol
	      RIP	to indicate that RIP/SAP should be used
	      NLSP	to indicate that Novell NLSP should be used
	      RIP NLSP	to indicate that both RIP/SAP and NLSP should be used

       /etc/ppp/ipx-down
	      A program or script which is executed when the link  is  no  longer  available  for
	      sending and receiving IPX packets.  This script can be used for undoing the effects
	      of the /etc/ppp/ipx-up script.  It is invoked in the same manner and with the  same
	      parameters as the ipx-up script.

FILES
       /var/run/pppn.pid (BSD or Linux), /etc/ppp/pppn.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).

       /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 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/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.

SEE ALSO
       RFC1144
	      Jacobson, V.  Compressing TCP/IP headers	for  low-speed	serial	links.	 February
	      1990.

       RFC1321
	      Rivest, R.  The MD5 Message-Digest Algorithm.  April 1992.

       RFC1332
	      McGregor, G.  PPP Internet Protocol Control Protocol (IPCP).  May 1992.

       RFC1334
	      Lloyd, B.; Simpson, W.A.	PPP authentication protocols.  October 1992.

       RFC1661
	      Simpson, W.A.  The Point-to-Point Protocol (PPP).  July 1994.

       RFC1662
	      Simpson, W.A.  PPP in HDLC-like Framing.	July 1994.

       RFC2472
	      Haskin, D.  IP Version 6 over PPP December 1998.

NOTES
       The following signals have the specified effect when sent to pppd.

       SIGINT, SIGTERM
	      These signals cause pppd to terminate the link (by closing LCP), restore the serial
	      device settings, and exit.

       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.

       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 imple-
	      mentation.)

AUTHORS
       Paul Mackerras (Paul.Mackerras@cs.anu.edu.au), based on earlier work by Drew Perkins, Brad
       Clements, Karl Fox, Greg Christy, and Brad Parker.

											  PPPD(8)


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