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pppd

PPPD(8)                                                                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  datagrams  over serial links, an
       extensible Link Control Protocol (LCP), and a family of Network Control
       Protocols  (NCP)  for  establishing  and configuring different network-
       layer protocols.

       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 Internet 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 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>
              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 limited 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) represents the character 0x00; bit 31 (80000000) rep-
              resents 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 char-
              acters.   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 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 over-
              ridden 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 unidirec-
              tional 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 spec-
              ified.

       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 transmis-
              sion (regardless of whether the peer requests them to be escaped
              with  its  async  control  character map).  The characters to be
              escaped are specified as a list of hex numbers separated by com-
              mas.   Note  that  almost any character can be specified for the
              escape option, unlike the asyncmap option which only allows con-
              trol  characters  to be specified.  The characters which may not
              be escaped are those with hex values 0x20 - 0x3f or 0x5e.

       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 ini-
              tialize 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  over-
              ridden 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 packets 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 with-
              out 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 conjunc-
              tion with the idle option if there are  packets  being  sent  or
              received  regularly over the link (for example, routing informa-
              tion 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 inap-
              propriate for a PPP link, such as ether and arp, are not permit-
              ted.  Generally the filter expression should be enclosed in sin-
              gle-quotes  to  prevent  whitespace in the expression from being
              interpreted by the shell. This option is currently  only  avail-
              able  under  NetBSD,  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  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).

       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  corre-
              sponding  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  con-
              trol  the  flow  of  data  on  the  serial port.  If neither the
              crtscts, the nocrtscts, the cdtrcts nor the nocdtrcts option  is
              given,  the hardware flow control setting for the serial port is
              left unchanged.  Some serial ports  (such  as  Macintosh  serial
              ports)  lack  a true RTS output. Such serial ports use this mode
              to implement true bi-directional flow control. The sacrifice  is
              that this flow control mode does not permit using DTR as a modem
              control line.

       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  chal-
              lenges) 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  packets  are  logged  through
              syslog  with  facility daemon and level debug.  This information
              can be directed to a file by setting up /etc/syslog.conf  appro-
              priately (see syslog.conf(5)).

       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 compression in the corre-
              sponding direction.  Use  nodeflate  or  deflate  0  to  disable
              Deflate compression entirely.  (Note: pppd requests Deflate com-
              pression in preference  to  BSD-Compress  if  the  peer  can  do
              either.)

       demand Initiate  the  link  only  on  demand, i.e. when data traffic is
              present.  With this option, the remote IP address must be speci-
              fied  by  the  user  on  the command line or in an options file.
              Pppd will initially configure the interface and enable it for IP
              traffic  without  connecting  to  the  peer.   When  traffic  is
              available, pppd will connect to the peer  and  perform  negotia-
              tion,  authentication,  etc.   When this is completed, pppd will
              commence passing data packets  (i.e.,  IP  packets)  across  the
              link.

              The demand option implies the persist option.  If this behaviour
              is not desired,  use  the  nopersist  option  after  the  demand
              option.  The idle and holdoff options are also useful in conjuc-
              tion with the demand option.

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

       dryrun With  the dryrun option, pppd will print out all the option val-
              ues which have been set and then exit, after parsing the command
              line  and  options  files  and  checking  the option values, but
              before initiating the link.  The option  values  are  logged  at
              level  info,  and  also  printed  to  standard output unless the
              device on standard output is the device that pppd would be using
              to communicate with the peer.

       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 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.

       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.

       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  pack-
              ets)  are  being sent or received.  Note: it is not advisable to
              use this option with  the  persist  option  without  the  demand
              option.   If  the  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-restart n
              Set the IPCP restart interval (retransmission timeout) to n sec-
              onds (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 sys-
              tem 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 argu-
              ment values depend on the specific kernel driver, but in general
              a  value  of 1 will enable general kernel debug messages.  (Note
              that these messages are usually only useful  for  debugging  the
              kernel  driver  itself.)  For the Linux 2.2.x kernel driver, the
              value is a sum of bits: 1 to enable general debug messages, 2 to
              request  that the contents of received packets be printed, and 4
              to request that the contents of transmitted packets be  printed.
              On  most  systems,  messages printed by the kernel are logged by
              syslog(1) to a file as directed in the /etc/syslog.conf configu-
              ration file.

       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  connec-
              tion.  Use of this option requires a non-zero value for the lcp-
              echo-interval parameter.  This option can be used to enable pppd
              to  terminate  after  the  physical  connection  has been broken
              (e.g., the modem has hung up) in situations  where  no  hardware
              modem control lines are available.

       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  sec-
              onds (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  sys-
              tems)  containing  its process ID.  This can be useful in deter-
              mining which instance of pppd is responsible for the link  to  a
              given peer system.  This is a privileged option.

       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 mes-
              sages 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 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.

       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 ter-
              minated  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 `mul-
              tilink' 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  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 (Win-
              dows Internet Name Services) server addresses  to  the  clients.
              The  first  instance  of  this option specifies the primary WINS
              address; the second instance (if given) specifies the  secondary
              WINS address.

       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 sec-
              tion 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 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 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 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  stan-
              dard  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 spec-
              ified, which is to determine (if possible) the local IP  address
              from the hostname.  With this option, the peer will have to sup-
              ply the local IP address  during  IPCP  negotiation  (unless  it
              specified explicitly on the command line or in an options file).

       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 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 speci-
              fied.

       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 pro-
              cess 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 sec-
              onds (default 3).

       pap-timeout n
              Set the maximum time that pppd will wait for the peer to authen-
              ticate itself with PAP to n seconds (0 means no limit).

       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 inap-
              propriate for a PPP link, such as ether and arp, are not permit-
              ted.  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 currently 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 Pre-
              dictor-1 compression, and agree to compress  transmitted  frames
              with Predictor-1 if requested.  This option has no effect unless
              the kernel driver supports Predictor-1 compression.

       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 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.  With-
              out 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 trans-
              fer  characters  between  the  pseudo-tty  and  the  real serial
              device, so it will increase the  latency  and  CPU  overhead  of
              transferring  data  over  the ppp interface.  The characters are
              stored in a tagged format with timestamps,  which  can  be  dis-
              played in readable form using the pppdump(8) program.

       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 Authentication Protocol] authentication.

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

       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).

       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.

       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).

       usehostname
              Enforce  the  use of the hostname (with domain name appended, if
              given) as the name of the local system for  authentication  pur-
              poses  (overrides the name option).  This option is not normally
              needed since the name option is privileged.

       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 Jacob-
              son 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.

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 whites-
       pace.  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 admin-
       istrator, or if pppd is being run by root.

       The  default  behaviour  of pppd is to allow an unauthenticated peer to
       use a given IP address only if the system does not already have a route
       to  that IP address.  For example, a system with a permanent connection
       to the wider internet will normally have a default route, and thus  all
       peers will have to authenticate themselves in order to set up a connec-
       tion.  On such a system, the auth option is the default.  On the  other
       hand,  a system where the PPP link is the only connection to the inter-
       net will not normally have a default route, so the peer will be able to
       use almost any IP address without authenticating itself.

       As  indicated  above,  some  security-sensitive options are privileged,
       which means that they may not be used  by  an  ordinary  non-privileged
       user  running  a  setuid-root  pppd, either on the command line, in the
       user's ~/.ppprc file, or in an options file read using the file option.
       Privileged  options  may  be  used  in  /etc/ppp/options  file or in an
       options file read using the call option.  If pppd is being run  by  the
       root user, privileged options can be used without restriction.

       When  opening  the device, pppd uses either the invoking user's user ID
       or the root UID (that is, 0), depending on whether the device name  was
       specified  by the user or the system administrator.  If the device name
       comes from a privileged source, that is, /etc/ppp/options or an options
       file  read  using  the call option, pppd uses full root privileges when
       opening the device.   Thus,  by  creating  an  appropriate  file  under
       /etc/ppp/peers, the system administrator can allow users to establish a
       ppp connection via a device which they would not normally have  permis-
       sion  to access.  Otherwise pppd uses the invoking user's real UID when
       opening the device.

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 pass-
       word) with the server, and authenticates  itself  by  proving  that  it
       knows  that secret.  Very often, the names used for authentication cor-
       respond to the internet hostnames of the peers, but this is not  essen-
       tial.

       At  present,  pppd  supports two authentication protocols: the Password
       Authentication Protocol (PAP) and the Challenge  Handshake  Authentica-
       tion  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 authenticate itself.  In that case, two separate and  indepen-
       dent  authentication exchanges will occur.  The two exchanges could use
       different authentication protocols, and in principle,  different  names
       could be used in the two exchanges.

       The default behaviour of pppd is to agree to authenticate if requested,
       and to not require authentication from the peer.   However,  pppd  will
       not  agree  to authenticate itself with a particular protocol if it has
       no secrets which could be used to do so.

       Pppd  stores  secrets  for  use  in  authentication  in  secrets  files
       (/etc/ppp/pap-secrets  for  PAP, /etc/ppp/chap-secrets for CHAP).  Both
       secrets files have the same format.   The  secrets  files  can  contain
       secrets  for  pppd to use in authenticating itself to other systems, as
       well as secrets for pppd to use when authenticating  other  systems  to
       itself.

       Each  line  in  a  secrets file contains one secret.  A given secret is
       specific to a particular combination of client and server - it can only
       be  used  by  that  client to authenticate itself to that server.  Thus
       each line in a secrets file has at least 3  fields:  the  name  of  the
       client,  the  name  of the server, and the secret.  These fields may be
       followed by a list of the IP addresses that the  specified  client  may
       use when connecting to the specified server.

       A  secrets  file  is  parsed  into  words as for a options file, so the
       client name, server name and secrets fields must each be one word, with
       any  embedded  spaces  or  other  special characters quoted or escaped.
       Note that case is significant in the client and server names and in the
       secret.

       If  the  secret  starts  with an `@', what follows is assumed to be the
       name of a file from which to read the secret.  A "*" as the  client  or
       server  name matches any name.  When selecting a secret, pppd takes the
       best match, i.e.  the match with the fewest wildcards.

       Any following words on the same line are taken to be a list of  accept-
       able  IP  addresses  for that client.  If there are only 3 words on the
       line, or if the first word is "-", then all  IP  addresses  are  disal-
       lowed.  To allow any address, use "*".  A word starting with "!"  indi-
       cates that the specified address is not acceptable.  An address may  be
       followed  by  "/"  and a number n, to indicate a whole subnet, i.e. all
       addresses which have the same value in the most significant n bits.  In
       this form, the address may be followed by a plus sign ("+") to indicate
       that one address from the subnet is authorized, based on the  ppp  net-
       work  interface unit number in use.  In this case, the host part of the
       address will be set to the unit number plus one.

       Thus a secrets file contains both secrets  for  use  in  authenticating
       other  hosts, plus secrets which we use for authenticating ourselves to
       others.  When pppd is authenticating  the  peer  (checking  the  peer's
       identity),  it chooses a secret with the peer's name in the first field
       and the name of the local system in the second field.  The name of  the
       local system defaults to the hostname, with the domain name appended if
       the domain option is used.  This default can  be  overridden  with  the
       name option, except when the usehostname option is used.

       When  pppd  is choosing a secret to use in authenticating itself to the
       peer, it first determines what name it is  going  to  use  to  identify
       itself  to  the  peer.  This name can be specified by the user with the
       user option.  If this option is not used, the name defaults to the name
       of the local system, determined as described in the previous paragraph.
       Then pppd looks for a secret with this name in the first field and  the
       peer's  name  in the second field.  Pppd will know the name of the peer
       if CHAP 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 remote-
       name option.  Otherwise, if the remote IP address was  specified  by  a
       name  (rather  than  in  numeric  form),  that name will be used as the
       peer's name.  Failing that, pppd will use the null string as the peer's
       name.

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

       Furthermore,  if the login option was specified, the username and pass-
       word are also checked against the system password database.  Thus,  the
       system  administrator  can  set  up  the  pap-secrets file to allow PPP
       access only to certain users, and to restrict the set of  IP  addresses
       that  each  user  can use.  Typically, when using the login option, the
       secret in /etc/ppp/pap-secrets would be "", which will match any  pass-
       word  supplied  by  the  peer.   This  avoids the need to have the same
       secret in two places.

       Authentication must be satisfactorily completed  before  IPCP  (or  any
       other  Network  Control  Protocol)  can  be  started.   If  the peer is
       required to authenticate itself, and fails to do so, pppd  will  termi-
       nated the link (by closing LCP).  If IPCP negotiates an unacceptable IP
       address for the remote host, IPCP will be closed.  IP packets can  only
       be sent or received when IPCP is open.

       In some cases it is desirable to allow some hosts which can't authenti-
       cate themselves to connect and use  one  of  a  restricted  set  of  IP
       addresses,  even when the local host generally requires authentication.
       If the peer refuses to authenticate itself when requested,  pppd  takes
       that  as  equivalent  to authenticating with PAP using the empty string
       for the username and password.  Thus, by adding  a  line  to  the  pap-
       secrets  file which specifies the empty string for the client and pass-
       word, it is possible to allow restricted access to hosts  which  refuse
       to authenticate themselves.

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

       Sometimes  it  is  desirable  to add a default route through the remote
       host, as in the case of a machine whose only connection to the Internet
       is  through  the ppp interface.  The defaultroute option causes pppd to
       create such a default route when IPCP comes up, and delete it when  the
       link is terminated.

       In some cases it is desirable to use proxy ARP, for example on a server
       machine connected to a LAN, in order to allow other hosts  to  communi-
       cate with the remote host.  The proxyarp option causes pppd to look for
       a network interface on the same subnet as the remote host (an interface
       supporting  broadcast  and ARP, which is up and not a point-to-point or
       loopback interface).  If found, pppd creates a permanent, published ARP
       entry  with  the IP address of the remote host and the hardware address
       of the network interface found.

       When the demand option is used, the interface IP addresses have already
       been set at the point when IPCP comes up.  If pppd has not been able to
       negotiate the same addresses that it used to  configure  the  interface
       (for  example  when  the  peer  is  an ISP that uses dynamic IP address
       assignment), pppd has to change the interface IP addresses to the nego-
       tiated  addresses.   This may disrupt existing connections, and the use
       of demand 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 indi-
       vidual links.  Currently, multilink PPP is only supported under  Linux.

       Pppd  detects  that the link it is controlling is connected to the same
       peer as another link using the peer's endpoint  discriminator  and  the
       authenticated  identity  of the peer (if it authenticates itself).  The
       endpoint discriminator is a block of data which is hopefully unique for
       each  peer.   Several  types  of  data  can be used, including locally-
       assigned strings  of  bytes,  IP  addresses,  MAC  addresses,  randomly
       strings  of  bytes, or E-164 phone numbers.  The endpoint discriminator
       sent to the peer by pppd can be set using the endpoint option.

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

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

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  con-
       tains  the  script used by chat; it could for example contain something
       like this:

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

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

       Pppd can also be used to provide a dial-in ppp service for  users.   If
       the  users  already have login accounts, the simplest way to set up the
       ppp service is to let the users log in to their accounts and  run  pppd
       (installed setuid-root) with a command such as

              pppd proxyarp

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

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

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

       If your serial connection is any more complicated than a piece of wire,
       you  may need to arrange for some control characters to be escaped.  In
       particular, it is often useful to escape XON (^Q) and XOFF (^S),  using
       asyncmap  a0000.   If  the  path includes a telnet, you probably should
       escape ^] as well (asyncmap 200a0000).  If the path includes an rlogin,
       you  will  need to use the escape ff option on the end which is running
       the rlogin client, since many rlogin implementations are not  transpar-
       ent; they will remove the sequence [0xff, 0xff, 0x73, 0x73, followed by
       any 8 bytes] from the stream.

DIAGNOSTICS
       Messages are sent to  the  syslog  daemon  using  facility  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 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.  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.

       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 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)  dur-
              ing 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.

       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

              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-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  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 pack-
              ets 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 parameters

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

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

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

       /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  privi-
              leged  options,  even  if  pppd was invoked by a user other than
              root.  The system administrator can create options files in this
              directory  to  permit  non-privileged  users to dial out without
              requiring the peer to authenticate, but only to certain  trusted
              peers.

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 implementation.)


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)