pppd(8) — Linux manual page

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

NAME         top

       pppd - Point-to-Point Protocol Daemon

SYNOPSIS         top

       pppd [ options ]

DESCRIPTION         top

       PPP is the protocol used for establishing internet links over
       dial-up modems, DSL connections, and many other types of point-
       to-point links.  The pppd daemon works together with the kernel
       PPP driver to establish and maintain a PPP link with another
       system (called the peer) and to negotiate Internet Protocol (IP)
       addresses for each end of the link.  Pppd can also authenticate
       the peer and/or supply authentication information to the peer.
       PPP can be used with other network protocols besides IP, but such
       use is becoming increasingly rare.

FREQUENTLY USED OPTIONS         top

       ttyname
              Use the serial port called ttyname to communicate with the
              peer.  If ttyname does not begin with a slash (/), the
              string "/dev/" is prepended to ttyname to form the name of
              the device to open.  If no device name is given, or if the
              name of the terminal connected to the standard input is
              given, pppd will use that terminal, and will not fork to
              put itself in the background.  A value for this option
              from a privileged source cannot be overridden by a non-
              privileged user.

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

       asyncmap map
              This option sets the Async-Control-Character-Map (ACCM)
              for this end of the link.  The ACCM is a set of 32 bits,
              one for each of the ASCII control characters with values
              from 0 to 31, where a 1 bit indicates that the
              corresponding control character should not be used in PPP
              packets sent to this system.  The map is encoded as a
              hexadecimal number (without a leading 0x) where the least
              significant bit (00000001) represents character 0 and the
              most significant bit (80000000) represents character 31.
              Pppd will ask the peer to send these characters as a
              2-byte escape sequence.  If multiple asyncmap options are
              given, the values are ORed together.  If no asyncmap
              option is given, the default is zero, so pppd will ask the
              peer not to escape any control characters.  To escape
              transmitted characters, use the escape option.

       auth   Require the peer to authenticate itself before allowing
              network packets to be sent or received.  This option is
              the default if the system has a default route.  If neither
              this option nor the noauth option is specified, pppd will
              only allow the peer to use IP addresses to which the
              system does not already have a route.

       call name
              Read additional options from the file /etc/ppp/peers/name.
              This file may contain privileged options, such as noauth,
              even if pppd is not being run by root.  The name string
              may not begin with / or include .. as a pathname
              component.  The format of the options file is described
              below.

       connect script
              Usually there is something which needs to be done to
              prepare the link before the PPP protocol can be started;
              for instance, with a dial-up modem, commands need to be
              sent to the modem to dial the appropriate phone number.
              This option specifies an command for pppd to execute (by
              passing it to a shell) before attempting to start PPP
              negotiation.  The chat (8) program is often useful here,
              as it provides a way to send arbitrary strings to a modem
              and respond to received characters.  A value for this
              option from a privileged source cannot be overridden by a
              non-privileged user.

       crtscts
              Specifies that pppd should set the serial port to use
              hardware flow control using the RTS and CTS signals in the
              RS-232 interface.  If neither the crtscts, the nocrtscts,
              the cdtrcts nor the nocdtrcts option is given, the
              hardware flow control setting for the serial port is left
              unchanged.  Some serial ports (such as Macintosh serial
              ports) lack a true RTS output. Such serial ports use this
              mode to implement unidirectional flow control. The serial
              port will suspend transmission when requested by the modem
              (via CTS) but will be unable to request the modem to stop
              sending to the computer. This mode retains the ability to
              use DTR as a modem control line.

       defaultroute
              Add a default route to the system routing tables, using
              the peer as the gateway, when IPCP negotiation is
              successfully completed.  This entry is removed when the
              PPP connection is broken.  This option is privileged if
              the nodefaultroute option has been specified.

       defaultroute-metric
              Define the metric of the defaultroute and only add it if
              there is no other default route with the same metric.
              With the default value of -1, the route is only added if
              there is no default route at all.

       replacedefaultroute
              This option is a flag to the defaultroute option. If
              defaultroute is set and this flag is also set, pppd
              replaces an existing default route with the new default
              route.  This option is privileged.

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

       escape xx,yy,...
              Specifies that certain characters should be escaped on
              transmission (regardless of whether the peer requests them
              to be escaped with its async control character map).  The
              characters to be escaped are specified as a list of hex
              numbers separated by commas.  Note that almost any
              character can be specified for the escape option, unlike
              the asyncmap option which only allows control characters
              to be specified.  The characters which may not be escaped
              are those with hex values 0x20 - 0x3f or 0x5e.

       file name
              Read options from file name (the format is described
              below).  The file must be readable by the user who has
              invoked pppd.

       init script
              Execute the command specified by script, by passing it to
              a shell, to initialize the serial line.  This script would
              typically use the chat(8) program to configure the modem
              to enable auto answer.  A value for this option from a
              privileged source cannot be overridden by a non-privileged
              user.

       lock   Specifies that pppd should create a UUCP-style lock file
              for the serial device to ensure exclusive access to the
              device.  By default, pppd will not create a lock file.

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

       mtu n  Set the MTU [Maximum Transmit Unit] value to n.  Unless
              the peer requests a smaller value via MRU negotiation,
              pppd will request that the kernel networking code send
              data packets of no more than n bytes through the PPP
              network interface.  Note that for the IPv6 protocol, the
              MTU must be at least 1280.

       passive
              Enables the "passive" option in the LCP.  With this
              option, pppd will attempt to initiate a connection; if no
              reply is received from the peer, pppd will then just wait
              passively for a valid LCP packet from the peer, instead of
              exiting, as it would without this option.

OPTIONS         top

       <local_IP_address>:<remote_IP_address>
              Set the local and/or remote interface IP addresses.
              Either one may be omitted.  The IP addresses can be
              specified with a host name or in decimal dot notation
              (e.g. 150.234.56.78).  The default local address is the
              (first) IP address of the system (unless the noipdefault
              option is given).  The remote address will be obtained
              from the peer if not specified in any option.  Thus, in
              simple cases, this option is not required.  If a local
              and/or remote IP address is specified with this option,
              pppd will not accept a different value from the peer in
              the IPCP negotiation, unless the ipcp-accept-local and/or
              ipcp-accept-remote options are given, respectively.

       +ipv6  Enable the IPv6CP and IPv6 protocols.

       ipv6 <local_interface_identifier>,<remote_interface_identifier>
              Set the local and/or remote 64-bit interface identifier.
              Either one may be omitted. The identifier must be
              specified in standard ASCII notation of IPv6 addresses
              (e.g. ::dead:beef). If the ipv6cp-use-ipaddr option is
              given, the local identifier is the local IPv4 address (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 conjunction with the idle option if
              there are packets being sent or received regularly over
              the link (for example, routing information packets) which
              would otherwise prevent the link from ever appearing to be
              idle.  The filter-expression syntax is as described for
              tcpdump(1), except that qualifiers which are inappropriate
              for a PPP link, such as ether and arp, are not permitted.
              Generally the filter expression should be enclosed in
              single-quotes to prevent whitespace in the expression from
              being interpreted by the shell. This option is currently
              only available under Linux, and requires that the kernel
              was configured to include PPP filtering support
              (CONFIG_PPP_FILTER).  Note that it is possible to apply
              different constraints to incoming and outgoing packets
              using the inbound and outbound qualifiers.

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

       allow-number number
              Allow peers to connect from the given telephone number.  A
              trailing `*' character will match all numbers beginning
              with the leading part.

       bsdcomp nr,nt
              Request that the peer compress packets that it sends,
              using the BSD-Compress scheme, with a maximum code size of
              nr bits, and agree to compress packets sent to the peer
              with a maximum code size of nt bits.  If nt is not
              specified, it defaults to the value given for nr.  Values
              in the range 9 to 15 may be used for nr and nt; larger
              values give better compression but consume more kernel
              memory for compression dictionaries.  Alternatively, a
              value of 0 for nr or nt disables compression in the
              corresponding direction.  Use nobsdcomp or bsdcomp 0 to
              disable BSD-Compress compression entirely.

       ca ca-file
              (EAP-TLS) Use the file ca-file as the X.509 Certificate
              Authority (CA) file (in PEM format), needed for setting up
              an EAP-TLS connection.  This option is used on the client-
              side in conjunction with the cert and key options.

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

       cert certfile
              (EAP-TLS) Use the file certfile as the X.509 certificate
              (in PEM format), needed for setting up an EAP-TLS
              connection. This option is used on the client-side in
              conjunction with the ca and key options.

       chap-interval n
              If this option is given, pppd will rechallenge the peer
              every n seconds.

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

       chap-restart n
              Set the CHAP restart interval (retransmission timeout for
              challenges) to n seconds (default 3).

       chap-timeout n
              Set timeout for CHAP authentication by peer to n seconds
              (default 60).

       chapms-strip-domain
              Some Windows 9x/ME clients might be transmitting the MS
              domain before the username in the provided client name.
              This option enables stripping the domain from the client
              name on the server side before matching it against the
              secret file.

       child-timeout n
              When exiting, wait for up to n seconds for any child
              processes (such as the command specified with the pty
              command) to exit before exiting.  At the end of the
              timeout, pppd will send a SIGTERM signal to any remaining
              child processes and exit.  A value of 0 means no timeout,
              that is, pppd will wait until all child processes have
              exited.

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

       crl filename
              (EAP-TLS) Use the file filename as the Certificate
              Revocation List to check for the validity of the peer's
              certificate. This option is not mandatory for setting up
              an EAP-TLS connection. Also see the crl-dir option.

       crl-dir directory
              (EAP-TLS) Use the directory directory to scan for CRL
              files in has format ($hash.r0) to check for the validity
              of the peer's certificate.  This option is not mandatory
              for setting up an EAP-TLS connection.  Also see the crl
              option.

       debug  Enables connection debugging facilities.  If this option
              is given, pppd will log the contents of all control
              packets sent or received in a readable form.  The packets
              are logged through syslog with facility daemon and level
              debug.  This information can be directed to a file by
              setting up /etc/syslog.conf appropriately (see
              syslog.conf(5)).

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

       default-mru
              Disable MRU [Maximum Receive Unit] negotiation.  With this
              option, pppd will use the default MRU value of 1500 bytes
              for both the transmit and receive direction.

       defaultroute6
              Add a default IPv6 route to the system routing tables,
              using the peer as the gateway, when IPv6CP negotiation is
              successfully completed.  This entry is removed when the
              PPP connection is broken.  This option is privileged if
              the nodefaultroute6 option has been specified.  WARNING:
              Do not enable this option by default.  IPv6 routing tables
              are managed by kernel (as apposite to IPv4) and IPv6
              default route is configured by kernel automatically too
              based on ICMPv6 Router Advertisement packets.  This option
              may conflict with kernel IPv6 route setup and should be
              used only for broken IPv6 networks.

       deflate nr,nt
              Request that the peer compress packets that it sends,
              using the Deflate scheme, with a maximum window size of
              2**nr bytes, and agree to compress packets sent to the
              peer with a maximum window size of 2**nt bytes.  If nt is
              not specified, it defaults to the value given for nr.
              Values in the range 9 to 15 may be used for nr and nt;
              larger values give better compression but consume more
              kernel memory for compression dictionaries.
              Alternatively, a value of 0 for nr or nt disables
              compression in the corresponding direction.  Use nodeflate
              or deflate 0 to disable Deflate compression entirely.
              (Note: pppd requests Deflate compression in preference to
              BSD-Compress if the peer can do either.)

       demand Initiate the link only on demand, i.e. when data traffic
              is present.  With this option, the remote IP address may
              be specified by the user on the command line or in an
              options file, or if not, pppd will use an arbitrary
              address in the 10.x.x.x range.  Pppd will initially
              configure the interface and enable it for IP traffic
              without connecting to the peer.  When traffic is
              available, pppd will connect to the peer and perform
              negotiation, authentication, etc.  When this is completed,
              pppd will commence passing data packets (i.e., IP packets)
              across the link.

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

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

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

       dump   With the dump option, pppd will print out all the option
              values which have been set.  This option is like the
              dryrun option except that pppd proceeds as normal rather
              than exiting.

       enable-session
              Enables session accounting via PAM or wtwp/wtmpx, as
              appropriate.  When PAM is enabled, the PAM "account" and
              "session" module stacks determine behavior, and are
              enabled for all PPP authentication protocols.  When PAM is
              disabled, wtmp/wtmpx entries are recorded regardless of
              whether the peer name identifies a valid user on the local
              system, making peers visible in the last(1) log.  This
              feature is automatically enabled when the pppd login
              option is used.  Session accounting is disabled by
              default.

       endpoint <epdisc>
              Sets the endpoint discriminator sent by the local machine
              to the peer during multilink negotiation to <epdisc>.  The
              default is to use the MAC address of the first ethernet
              interface on the system, if any, otherwise the IPv4
              address corresponding to the hostname, if any, provided it
              is not in the multicast or locally-assigned IP address
              ranges, or the localhost address.  The endpoint
              discriminator can be the string null or of the form
              type:value, where type is a decimal number or one of the
              strings local, IP, MAC, magic, or phone.  The value is an
              IP address in dotted-decimal notation for the IP type, or
              a string of bytes in hexadecimal, separated by periods or
              colons for the other types.  For the MAC type, the value
              may also be the name of an ethernet or similar network
              interface.  This option is currently only available under
              Linux.

       eap-interval n
              If this option is given and pppd authenticates the peer
              with EAP (i.e., is the server), pppd will restart EAP
              authentication every n seconds.  For EAP SRP-SHA1, see
              also the srp-interval option, which enables lightweight
              rechallenge.

       eap-max-rreq n
              Set the maximum number of EAP Requests to which pppd will
              respond (as a client) without hearing EAP Success or
              Failure.  (Default is 20.)

       eap-max-sreq n
              Set the maximum number of EAP Requests that pppd will
              issue (as a server) while attempting authentication.
              (Default is 10.)

       eap-restart n
              Set the retransmit timeout for EAP Requests when acting as
              a server (authenticator).  (Default is 3 seconds.)

       eap-timeout n
              Set the maximum time to wait for the peer to send an EAP
              Request when acting as a client (authenticatee).  (Default
              is 20 seconds.)

       hide-password
              When logging the contents of PAP packets, this option
              causes pppd to exclude the password string from the log.
              This is the default.

       holdoff n
              Specifies how many seconds to wait before re-initiating
              the link after it terminates.  This option only has any
              effect if the persist or demand option is used.  The
              holdoff period is not applied if the link was terminated
              because it was idle.

       idle n Specifies that pppd should disconnect if the link is idle
              for n seconds.  The link is idle when no data packets
              (i.e. IP packets) are being sent or received.  Note: it is
              not advisable to use this option with the persist option
              without the demand option.  If the active-filter option is
              given, data packets which are rejected by the specified
              activity filter also count as the link being idle.

       ipcp-accept-local
              With this option, pppd will accept the peer's idea of our
              local IP address, even if the local IP address was
              specified in an option.

       ipcp-accept-remote
              With this option, pppd will accept the peer's idea of its
              (remote) IP address, even if the remote IP address was
              specified in an option.

       ipcp-max-configure n
              Set the maximum number of IPCP configure-request
              transmissions to n (default 10).

       ipcp-max-failure n
              Set the maximum number of IPCP configure-NAKs returned
              before starting to send configure-Rejects instead to n
              (default 10).

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

       ipcp-no-address
              Disable negotiation of addresses via IP-Address IPCP
              option.

       ipcp-no-addresses
              Disable negotiation of addresses via old-style deprecated
              IP-Addresses IPCP option. pppd by default try to use new-
              style IP-Address IPCP option.  If new-style is not
              supported by peer or is disabled by ipcp-no-address option
              then pppd fallbacks to old-style deprecated IP-Addresses
              IPCP option.  When both new-style and old-style are
              disabled by both ipcp-no-address and ipcp-no-addresses
              options then negotiation of IP addresses is completely
              disabled.

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

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

       ipv6cp-accept-local
              With this option, pppd will accept the peer's idea of our
              local IPv6 interface identifier, even if the local IPv6
              interface identifier was specified in an option.

       ipv6cp-accept-remote
              With this option, pppd will accept the peer's idea of its
              (remote) IPv6 interface identifier, even if the remote
              IPv6 interface identifier was specified in an option.

       ipv6cp-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 number 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 kernel debug
              messages.  (Note that these messages are usually only
              useful for debugging the kernel driver itself.)  For the
              Linux 2.2.x kernel driver, the value is a sum of bits: 1
              to enable general debug messages, 2 to request that the
              contents of received packets be printed, and 4 to request
              that the contents of transmitted packets be printed.  On
              most systems, messages printed by the kernel are logged by
              syslog(1) to a file as directed in the /etc/syslog.conf
              configuration file.

       key keyfile
              (EAP-TLS) Use the file keyfile as the private key file (in
              PEM format), needed for setting up an EAP-TLS connection.
              This option is used on the client-side in conjunction with
              the ca and cert options.

       ktune  Enables pppd to alter kernel settings as appropriate.
              Under Linux, pppd will enable IP forwarding (i.e. set
              /proc/sys/net/ipv4/ip_forward to 1) if the proxyarp option
              is used, and will enable the dynamic IP address option
              (i.e. set /proc/sys/net/ipv4/ip_dynaddr to 1) in demand
              mode if the local address changes.

       lcp-echo-adaptive
              If this option is used with the lcp-echo-failure option
              then pppd will send LCP echo-request frames only if no
              traffic was received from the peer since the last
              echo-request was sent.

       lcp-echo-failure n
              If this option is given, pppd will presume the peer to be
              dead if n LCP echo-requests are sent without receiving a
              valid LCP echo-reply.  If this happens, pppd will
              terminate the connection.  Use of this option requires a
              non-zero value for the lcp-echo-interval parameter.  This
              option can be used to enable pppd to terminate after the
              physical connection has been broken (e.g., the modem has
              hung up) in situations where no hardware modem control
              lines are available.

       lcp-echo-interval n
              If this option is given, pppd will send an LCP
              echo-request frame to the peer every n seconds.  Normally
              the peer should respond to the echo-request by sending an
              echo-reply.  This option can be used with the
              lcp-echo-failure option to detect that the peer is no
              longer connected.

       lcp-max-configure n
              Set the maximum number of LCP configure-request
              transmissions to n (default 10).

       lcp-max-failure n
              Set the maximum number of LCP configure-NAKs returned
              before starting to send configure-Rejects instead to n
              (default 10).

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

       lcp-restart n
              Set the LCP restart interval (retransmission timeout) to n
              seconds (default 3).

       linkname name
              Sets the logical name of the link to name.  Pppd will
              create a file named ppp-name.pid in /var/run (or /etc/ppp
              on some systems) containing its process ID.  This can be
              useful in determining which instance of pppd is
              responsible for the link to a given peer system.  This is
              a privileged option.

       local  Don't use the modem control lines.  With this option, pppd
              will ignore the state of the CD (Carrier Detect) signal
              from the modem and will not change the state of the DTR
              (Data Terminal Ready) signal.  This is the opposite of the
              modem option.

       logfd n
              Send log messages to file descriptor n.  Pppd will send
              log messages to at most one file or file descriptor (as
              well as sending the log messages to syslog), so this
              option and the logfile option are mutually exclusive.  The
              default is for pppd to send log messages to stdout (file
              descriptor 1), unless the serial port is already open on
              stdout.

       logfile filename
              Append log messages to the file filename (as well as
              sending the log messages to syslog).  The file is opened
              with the privileges of the user who invoked pppd, in
              append mode.

       login  Use the system password database for authenticating the
              peer using PAP, and record the user in the system wtmp
              file.  Note that the peer must have an entry in the
              /etc/ppp/pap-secrets file as well as the system password
              database to be allowed access.  See also the
              enable-session option.

       master_detach
              If multilink is enabled and this pppd process is the
              multilink bundle master, and the link controlled by this
              pppd process terminates, this pppd process continues to
              run in order to maintain the bundle.  If the master_detach
              option has been given, pppd will detach from its
              controlling terminal in this situation, even if the
              nodetach option has been given.

       maxconnect n
              Terminate the connection when it has been available for
              network traffic for n seconds (i.e. n seconds after the
              first network control protocol comes up).

       maxfail n
              Terminate after n consecutive failed connection attempts.
              A value of 0 means no limit.  The default value is 10.

       modem  Use the modem control lines.  This option is the default.
              With this option, pppd will wait for the CD (Carrier
              Detect) signal from the modem to be asserted when opening
              the serial device (unless a connect script is specified),
              and it will drop the DTR (Data Terminal Ready) signal
              briefly when the connection is terminated and before
              executing the connect script.  On Ultrix, this option
              implies hardware flow control, as for the crtscts option.
              This is the opposite of the local option.

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

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

       mpshortseq
              Enables the use of short (12-bit) sequence numbers in
              multilink headers, as opposed to 24-bit sequence numbers.
              This option is only available under Linux, and only has
              any effect if multilink is enabled (see the multilink
              option).

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

       ms-dns <addr>
              If pppd is acting as a server for Microsoft Windows
              clients, this option allows pppd to supply one or two DNS
              (Domain Name Server) addresses to the clients.  The first
              instance of this option specifies the primary DNS address;
              the second instance (if given) specifies the secondary DNS
              address.  (This option was present in some older versions
              of pppd under the name dns-addr.)

       ms-wins <addr>
              If pppd is acting as a server for Microsoft Windows or
              "Samba" clients, this option allows pppd to supply one or
              two WINS (Windows Internet Name Services) server addresses
              to the clients.  The first instance of this option
              specifies the primary WINS address; the second instance
              (if given) specifies the secondary WINS address.

       multilink
              Enables the use of the PPP multilink protocol.  If the
              peer also supports multilink, then this link can become
              part of a bundle between the local system and the peer.
              If there is an existing bundle to the peer, pppd will join
              this link to that bundle, otherwise pppd will create a new
              bundle.  See the MULTILINK section below.  This option is
              currently only available under Linux.

       name name
              Set the name of the local system for authentication
              purposes to name.  This is a privileged option.  With this
              option, pppd will use lines in the secrets files which
              have name as the second field when looking for a secret to
              use in authenticating the peer.  In addition, unless
              overridden with the user option, name will be used as the
              name to send to the peer when authenticating the local
              system to the peer.  (Note that pppd does not append the
              domain name to name.)

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

       need-peer-eap
              (EAP-TLS) Require the peer to verify our authentication
              credentials.

       noauth Do not require the peer to authenticate itself.  This
              option is privileged.

       nobsdcomp
              Disables BSD-Compress compression; pppd will not request
              or agree to compress packets using the BSD-Compress
              scheme.

       noccp  Disable CCP (Compression Control Protocol) negotiation.
              This option should only be required if the peer is buggy
              and gets confused by requests from pppd for CCP
              negotiation.

       nocrtscts
              Disable hardware flow control (i.e. RTS/CTS) on the serial
              port.  If neither the crtscts nor the nocrtscts nor the
              cdtrcts nor the nocdtrcts option is given, the hardware
              flow control setting for the serial port is left
              unchanged.

       nocdtrcts
              This option is a synonym for nocrtscts. Either of these
              options will disable both forms of hardware flow control.

       nodefaultroute
              Disable the defaultroute option.  The system administrator
              who wishes to prevent users from adding a default route
              with pppd can do so by placing this option in the
              /etc/ppp/options file.

       noreplacedefaultroute
              Disable the replacedefaultroute option. This allows to
              disable a replacedefaultroute option set previously in the
              configuration.

       nodefaultroute6
              Disable the defaultroute6 option.  The system
              administrator who wishes to prevent users from adding a
              default route with pppd can do so by placing this option
              in the /etc/ppp/options file.

       nodeflate
              Disables Deflate compression; pppd will not request or
              agree to compress packets using the Deflate scheme.

       nodetach
              Don't detach from the controlling terminal.  Without this
              option, if a serial device other than the terminal on the
              standard input is specified, pppd will fork to become a
              background process.

       noendpoint
              Disables pppd from sending an endpoint discriminator to
              the peer or accepting one from the peer (see the MULTILINK
              section below).  This option should only be required if
              the peer is buggy.

       noip   Disable IPCP negotiation and IP communication.  This
              option should only be required if the peer is buggy and
              gets confused by requests from pppd for IPCP negotiation.

       noipv6 Disable IPv6CP negotiation and IPv6 communication. This
              option should only be required if the peer is buggy and
              gets confused by requests from pppd for IPv6CP
              negotiation.

       noipdefault
              Disables the default behaviour when no local IP address is
              specified, which is to determine (if possible) the local
              IP address from the hostname.  With this option, the peer
              will have to supply the local IP address during IPCP
              negotiation (unless it specified explicitly on the command
              line or in an options file).

       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.

       nolock Opposite of the lock option; specifies that pppd should
              not create a UUCP-style lock file for the serial device.
              This option is privileged.

       nolog  Do not send log messages to a file or file descriptor.
              This option cancels the logfd and logfile options.

       nomagic
              Disable magic number negotiation.  With this option, pppd
              cannot detect a looped-back line.  This option should only
              be needed if the peer is buggy.

       nomp   Disables the use of PPP multilink.  This option is
              currently only available under Linux.

       nomppe Disables MPPE (Microsoft Point to Point Encryption).  This
              is the default.

       nomppe-40
              Disable 40-bit encryption with MPPE.

       nomppe-128
              Disable 128-bit encryption with MPPE.

       nomppe-stateful
              Disable MPPE stateful mode.  This is the default.

       nompshortseq
              Disables the use of short (12-bit) sequence numbers in the
              PPP multilink protocol, forcing the use of 24-bit sequence
              numbers.  This option is currently only available under
              Linux, and only has any effect if multilink is enabled.

       nomultilink
              Disables the use of PPP multilink.  This option is
              currently only available under Linux.

       nopcomp
              Disable protocol field compression negotiation in both the
              receive and the transmit direction.

       nopersist
              Exit once a connection has been made and terminated.  This
              is the default unless the persist or demand option has
              been specified.

       nopredictor1
              Do not accept or agree to Predictor-1 compression.

       noproxyarp
              Disable the proxyarp option.  The system administrator who
              wishes to prevent users from creating proxy ARP entries
              with pppd can do so by placing this option in the
              /etc/ppp/options file.

       noremoteip
              Allow pppd to operate without having an IP address for the
              peer.  This option is only available under Linux.
              Normally, pppd will request the peer's IP address, and if
              the peer does not supply it, pppd will use an arbitrary
              address in the 10.x.x.x subnet.  With this option, if the
              peer does not supply its IP address, pppd will not ask the
              peer for it, and will not set the destination address of
              the ppp interface.  In this situation, the ppp interface
              can be used for routing by creating device routes, but the
              peer itself cannot be addressed directly for IP traffic.

       nosendip
              Don't send our local IP address to peer during IP address
              negotiation.

       notty  Normally, pppd requires a terminal device.  With this
              option, pppd will allocate itself a pseudo-tty
              master/slave pair and use the slave as its terminal
              device.  Pppd will create a child process to act as a
              `character shunt' to transfer characters between the
              pseudo-tty master and its standard input and output.  Thus
              pppd will transmit characters on its standard output and
              receive characters on its standard input even if they are
              not terminal devices.  This option increases the latency
              and CPU overhead of transferring data over the ppp
              interface as all of the characters sent and received must
              flow through the character shunt process.  An explicit
              device name may not be given if this option is used.

       novj   Disable Van Jacobson style TCP/IP header compression in
              both the transmit and the receive direction.

       novjccomp
              Disable the connection-ID compression option in Van
              Jacobson style TCP/IP header compression.  With this
              option, pppd will not omit the connection-ID byte from Van
              Jacobson compressed TCP/IP headers, nor ask the peer to do
              so.

       papcrypt
              Indicates that all secrets in the /etc/ppp/pap-secrets
              file which are used for checking the identity of the peer
              are encrypted, and thus pppd should not accept a password
              which, before encryption, is identical to the secret from
              the /etc/ppp/pap-secrets file.

       pap-max-authreq n
              Set the maximum number of PAP authenticate-request
              transmissions to n (default 10).

       pap-restart n
              Set the PAP restart interval (retransmission timeout) to n
              seconds (default 3).

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

       pass-filter filter-expression
              Specifies a packet filter to applied to data packets being
              sent or received to determine which packets should be
              allowed to pass.  Packets which are rejected by the filter
              are silently discarded.  This option can be used to
              prevent specific network daemons (such as routed) using up
              link bandwidth, or to provide a very basic firewall
              capability.  The filter-expression syntax is as described
              for tcpdump(1), except that qualifiers which are
              inappropriate for a PPP link, such as ether and arp, are
              not permitted.  Generally the filter expression should be
              enclosed in single-quotes to prevent whitespace in the
              expression from being interpreted by the shell.  Note that
              it is possible to apply different constraints to incoming
              and outgoing packets using the inbound and outbound
              qualifiers. This option is currently only available under
              Linux, and requires that the kernel was configured to
              include PPP filtering support (CONFIG_PPP_FILTER).

       password password-string
              Specifies the password to use for authenticating to the
              peer.  Use of this option is discouraged, as the password
              is likely to be visible to other users on the system (for
              example, by using ps(1)).

       persist
              Do not exit after a connection is terminated; instead try
              to reopen the connection. The maxfail option still has an
              effect on persistent connections.

       plugin filename
              Load the shared library object file filename as a plugin.
              This is a privileged option.  If filename does not contain
              a slash (/), pppd will look in the /usr/lib/pppd/version
              directory for the plugin, where version is the version
              number of pppd (for example, 2.4.2).

       predictor1
              Request that the peer compress frames that it sends using
              Predictor-1 compression, and agree to compress transmitted
              frames with Predictor-1 if requested.  This option has no
              effect unless the kernel driver supports Predictor-1
              compression.

       privgroup group-name
              Allows members of group group-name to use privileged
              options.  This is a privileged option.  Use of this option
              requires care as there is no guarantee that members of
              group-name cannot use pppd to become root themselves.
              Consider it equivalent to putting the members of
              group-name in the kmem or disk group.

       proxyarp
              Add an entry to this system's ARP [Address Resolution
              Protocol] table with the IP address of the peer and the
              Ethernet address of this system.  This will have the
              effect of making the peer appear to other systems to be on
              the local ethernet.

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

       receive-all
              With this option, pppd will accept all control characters
              from the peer, including those marked in the receive
              asyncmap.  Without this option, pppd will discard those
              characters as specified in RFC1662.  This option should
              only be needed if the peer is buggy.

       record filename
              Specifies that pppd should record all characters sent and
              received to a file named filename.  This file is opened in
              append mode, using the user's user-ID and permissions.
              This option is implemented using a pseudo-tty and a
              process to transfer characters between the pseudo-tty and
              the real serial device, so it will increase the latency
              and CPU overhead of transferring data over the ppp
              interface.  The characters are stored in a tagged format
              with timestamps, which can be displayed in readable form
              using the pppdump(8) program.

       remotename name
              Set the assumed name of the remote system for
              authentication purposes to name.

       remotenumber number
              Set the assumed telephone number of the remote system for
              authentication purposes to number.

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

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

       refuse-mschap-v2
              With this option, pppd will not agree to authenticate
              itself to the peer using MS-CHAPv2.

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

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

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

       require-mppe
              Require the use of MPPE (Microsoft Point to Point
              Encryption).  This option disables all other compression
              types.  This option enables both 40-bit and 128-bit
              encryption.  In order for MPPE to successfully come up,
              you must have authenticated with either MS-CHAP or
              MS-CHAPv2.  This option is presently only supported under
              Linux, and only if your kernel has been configured to
              include MPPE support.

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

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

       require-mschap
              Require the peer to authenticate itself using MS-CHAP
              [Microsoft Challenge Handshake Authentication Protocol]
              authentication.

       require-mschap-v2
              Require the peer to authenticate itself using MS-CHAPv2
              [Microsoft Challenge Handshake Authentication Protocol,
              Version 2] authentication.

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

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

       set name=value
              Set an environment variable for scripts that are invoked
              by pppd.  When set by a privileged source, the variable
              specified by name cannot be changed by options contained
              in an unprivileged source.  See also the unset option and
              the environment described in SCRIPTS.

       show-password
              When logging the contents of PAP packets, this option
              causes pppd to show the password string in the log
              message.

       silent With this option, pppd will not transmit LCP packets to
              initiate a connection until a valid LCP packet is received
              from the peer (as for the `passive' option with ancient
              versions of pppd).

       srp-interval n
              If this parameter is given and pppd uses EAP SRP-SHA1 to
              authenticate the peer (i.e., is the server), then pppd
              will use the optional lightweight SRP rechallenge
              mechanism at intervals of n seconds.  This option is
              faster than eap-interval reauthentication because it uses
              a hash-based mechanism and does not derive a new session
              key.

       srp-pn-secret string
              Set the long-term pseudonym-generating secret for the
              server.  This value is optional and if set, needs to be
              known at the server (authenticator) side only, and should
              be different for each server (or poll of identical
              servers).  It is used along with the current date to
              generate a key to encrypt and decrypt the client's
              identity contained in the pseudonym.

       srp-use-pseudonym
              When operating as an EAP SRP-SHA1 client, attempt to use
              the pseudonym stored in ~/.ppp_pseudonym first as the
              identity, and save in this file any pseudonym offered by
              the peer during authentication.

       stop-bits n
              Set the number of stop bits for the serial port. Valid
              values are 1 or 2.  The default value is 1.

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

       unit num
              Sets the ppp unit number (for a ppp0 or ppp1 etc interface
              name) for outbound connections.  If the unit is already in
              use a dynamically allocated number will be used.

       ifname string
              Set the ppp interface name for outbound connections.  If
              the interface name is already in use, or if the name
              cannot be used for any other reason, pppd will terminate.

       unset name
              Remove a variable from the environment variable for
              scripts that are invoked by pppd.  When specified by a
              privileged source, the variable name cannot be set by
              options contained in an unprivileged source.  See also the
              set option and the environment described in SCRIPTS.

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

       up_sdnotify
              Use this option to run pppd in systemd service units of
              Type=notify (up_sdnotify implies nodetach).  When
              up_sdnotify is enabled, pppd will notify systemd once it
              has successfully established the ppp connection (to the
              point where the first network control protocl, usually the
              IP control protocol, has come up). This option is only
              availble when pppd is compiled with systemd support.

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

       usepeerdns
              Ask the peer for up to 2 DNS server addresses.  The
              addresses supplied by the peer (if any) are passed to the
              /etc/ppp/ip-up script in the environment variables DNS1
              and DNS2, and the environment variable USEPEERDNS will be
              set to 1.  In addition, pppd will create an
              /etc/ppp/resolv.conf file containing one or two nameserver
              lines with the address(es) supplied by the peer.

       user name
              Sets the name used for authenticating the local system to
              the peer to name.

       vj-max-slots n
              Sets the number of connection slots to be used by the Van
              Jacobson TCP/IP header compression and decompression code
              to n, which must be between 2 and 16 (inclusive).

       welcome script
              Run the executable or shell command specified by script
              before initiating PPP negotiation, after the connect
              script (if any) has completed.  A value for this option
              from a privileged source cannot be overridden by a non-
              privileged user.

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

PPPOE OPTIONS         top

       To establish PPP link over Ethernet (PPPoE) it is needed to load
       pppd's plugin pppoe.so and then specify option nic-interface
       instead of modem options ttyname and speed.  Recognized pppd's
       PPPoE options are:

       nic-interface
              Use the ethernet device interface to communicate with the
              peer.  For example, establishing PPPoE link on eth0
              interface is done by specifying ppp'd option nic-eth0.
              Prefix nic- for this option may be avoided if interface
              name is unambiguous and does not look like any other
              pppd's option.

       pppoe-service name
              Connect to specified PPPoE service name. For backward
              compatibility also rp_pppoe_service option name is
              supported.

       pppoe-ac name
              Connect to specified PPPoE access concentrator name. For
              backward compatibility also rp_pppoe_ac option name is
              supported.

       pppoe-sess sessid:macaddr
              Attach to existing PPPoE session. For backward
              compatibility also rp_pppoe_sess option name is supported.

       pppoe-verbose n
              Be verbose about discovered access concentrators. For
              backward compatibility also rp_pppoe_verbose option name
              is supported.

       pppoe-mac macaddr
              Connect to specified MAC address.

       pppoe-host-uniq string
              Set the PPPoE Host-Uniq tag to the supplied hex string.
              By default PPPoE Host-Uniq tag is set to the pppd's
              process PID.  For backward compatibility this option may
              be specified without pppoe- prefix.

       pppoe-padi-timeout n
              Initial timeout for discovery packets in seconds (default
              5).

       pppoe-padi-attempts n
              Number of discovery attempts (default 3).

OPTIONS FILES         top

       Options can be taken from files as well as the command line.
       Pppd reads options from the files /etc/ppp/options, ~/.ppprc and
       /etc/ppp/options.ttyname (in that order) before processing the
       options on the command line.  (In fact, the command-line options
       are scanned to find the terminal name before the options.ttyname
       file is read.)  In forming the name of the options.ttyname file,
       the initial /dev/ is removed from the terminal name, and any
       remaining / characters are replaced with dots.

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

SECURITY         top

       pppd provides system administrators with sufficient access
       control that PPP access to a server machine can be provided to
       legitimate users without fear of compromising the security of the
       server or the network it's on.  This control is provided through
       restrictions on which IP addresses the peer may use, based on its
       authenticated identity (if any), and through restrictions on
       which options a non-privileged user may use.  Several of pppd's
       options are privileged, in particular those which permit
       potentially insecure configurations; these options are only
       accepted in files which are under the control of the system
       administrator, or if pppd is being run by root.

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

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

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

AUTHENTICATION         top

       Authentication is the process whereby one peer convinces the
       other of its identity.  This involves the first peer sending its
       name to the other, together with some kind of secret information
       which could only come from the genuine authorized user of that
       name.  In such an exchange, we will call the first peer the
       "client" and the other the "server".  The client has a name by
       which it identifies itself to the server, and the server also has
       a name by which it identifies itself to the client.  Generally
       the genuine client shares some secret (or password) with the
       server, and authenticates itself by proving that it knows that
       secret.  Very often, the names used for authentication correspond
       to the internet hostnames of the peers, but this is not
       essential.

       At present, pppd supports three authentication protocols: the
       Password Authentication Protocol (PAP), Challenge Handshake
       Authentication Protocol (CHAP), and Extensible Authentication
       Protocol (EAP).  PAP involves the client sending its name and a
       cleartext password to the server to authenticate itself.  In
       contrast, the server initiates the CHAP authentication exchange
       by sending a challenge to the client (the challenge packet
       includes the server's name).  The client must respond with a
       response which includes its name plus a hash value derived from
       the shared secret and the challenge, in order to prove that it
       knows the secret.  EAP supports CHAP-style authentication, and
       also includes the SRP-SHA1 mechanism, which is resistant to
       dictionary-based attacks and does not require a cleartext
       password on the server side.

       The PPP protocol, being symmetrical, allows both peers to require
       the other to authenticate itself.  In that case, two separate and
       independent authentication exchanges will occur.  The two
       exchanges could use different authentication protocols, and in
       principle, different names could be used in the two exchanges.

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

       Pppd stores secrets for use in authentication in secrets files
       (/etc/ppp/pap-secrets for PAP, /etc/ppp/chap-secrets for CHAP,
       MS-CHAP, MS-CHAPv2, and EAP MD5-Challenge, and
       /etc/ppp/srp-secrets for EAP SRP-SHA1).  All secrets files have
       the same format.  The secrets files can contain secrets for pppd
       to use in authenticating itself to other systems, as well as
       secrets for pppd to use when authenticating other systems to
       itself.

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

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

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

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

       Thus a secrets file contains both secrets for use in
       authenticating other hosts, plus secrets which we use for
       authenticating ourselves to others.  When pppd is authenticating
       the peer (checking the peer's identity), it chooses a secret with
       the peer's name in the first field and the name of the local
       system in the second field.  The name of the local system
       defaults to the hostname, with the domain name appended if the
       domain option is used.  This default can be overridden with the
       name option, except when the usehostname option is used.  (For
       EAP SRP-SHA1, see the srp-entry(8) utility for generating proper
       validator entries to be used in the "secret" field.)

       When pppd is choosing a secret to use in authenticating itself to
       the peer, it first determines what name it is going to use to
       identify itself to the peer.  This name can be specified by the
       user with the user option.  If this option is not used, the name
       defaults to the name of the local system, determined as described
       in the previous paragraph.  Then pppd looks for a secret with
       this name in the first field and the peer's name in the second
       field.  Pppd will know the name of the peer if CHAP or EAP
       authentication is being used, because the peer will have sent it
       in the challenge packet.  However, if PAP is being used, pppd
       will have to determine the peer's name from the options specified
       by the user.  The user can specify the peer's name directly with
       the remotename option.  Otherwise, if the remote IP address was
       specified by a name (rather than in numeric form), that name will
       be used as the peer's name.  Failing that, pppd will use the null
       string as the peer's name.

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

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

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

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

ROUTING         top

       When IPCP negotiation is completed successfully, pppd will inform
       the kernel of the local and remote IP addresses for the ppp
       interface.  This is sufficient to create a host route to the
       remote end of the link, which will enable the peers to exchange
       IP packets.  Communication with other machines generally requires
       further modification to routing tables and/or ARP (Address
       Resolution Protocol) tables.  In most cases the defaultroute
       and/or proxyarp options are sufficient for this, but in some
       cases further intervention is required.  The /etc/ppp/ip-up
       script can be used for this.

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

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

       When the demand option is used, the interface IP addresses have
       already been set at the point when IPCP comes up.  If pppd has
       not been able to negotiate the same addresses that it used to
       configure the interface (for example when the peer is an ISP that
       uses dynamic IP address assignment), pppd has to change the
       interface IP addresses to the negotiated addresses.  This may
       disrupt existing connections, and the use of demand dialling with
       peers that do dynamic IP address assignment is not recommended.

MULTILINK         top

       Multilink PPP provides the capability to combine two or more PPP
       links between a pair of machines into a single `bundle', which
       appears as a single virtual PPP link which has the combined
       bandwidth of the individual links.  Currently, multilink PPP is
       only supported under Linux.

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

       In some circumstances the peer may send no endpoint discriminator
       or a non-unique value.  The bundle option adds an extra string
       which is added to the peer's endpoint discriminator and
       authenticated identity when matching up links to be joined
       together in a bundle.  The bundle option can also be used to
       allow the establishment of multiple bundles between the local
       system and the peer.  Pppd uses a TDB database in
       /var/run/pppd2.tdb to match up links.

       Assuming that multilink is enabled and the peer is willing to
       negotiate multilink, then when pppd is invoked to bring up the
       first link to the peer, it will detect that no other link is
       connected to the peer and create a new bundle, that is, another
       ppp network interface unit.  When another pppd is invoked to
       bring up another link to the peer, it will detect the existing
       bundle and join its link to it.

       If the first link terminates (for example, because of a hangup or
       a received LCP terminate-request) the bundle is not destroyed
       unless there are no other links remaining in the bundle.  Rather
       than exiting, the first pppd keeps running after its link
       terminates, until all the links in the bundle have terminated.
       If the first pppd receives a SIGTERM or SIGINT signal, it will
       destroy the bundle and send a SIGHUP to the pppd processes for
       each of the links in the bundle.  If the first pppd receives a
       SIGHUP signal, it will terminate its link but not the bundle.

       Note: demand mode is not currently supported with multilink.

EXAMPLES         top

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

       Probably the most common use of pppd is to dial out to an ISP.
       This can be done with a command such as

              pppd call isp

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

              ttyS0 19200 crtscts
              connect '/usr/sbin/chat -v -f /etc/ppp/chat-isp'
              noauth

       In this example, we are using chat to dial the ISP's modem and go
       through any logon sequence required.  The /etc/ppp/chat-isp file
       contains the script used by chat; it could for example contain
       something like this:

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

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

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

              pppd proxyarp

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

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

       (See srp-entry(8) for a means to generate the server's entry when
       SRP-SHA1 is in use.)  Alternatively, you can create a username
       called (for example) "ppp", whose login shell is pppd and whose
       home directory is /etc/ppp.  Options to be used when pppd is run
       this way can be put in /etc/ppp/.ppprc.

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

DIAGNOSTICS         top

       Messages are sent to the syslog daemon using facility LOG_DAEMON.
       (This can be overridden by recompiling pppd with the macro
       LOG_PPP defined as the desired facility.)  See the syslog(8)
       documentation for details of where the syslog daemon will write
       the messages.  On most systems, the syslog daemon uses the
       /etc/syslog.conf file to specify the destination(s) for syslog
       messages.  You may need to edit that file to suit.

       The debug option causes the contents of all control packets sent
       or received to be logged, that is, all LCP, PAP, CHAP, EAP, or
       IPCP packets.  This can be useful if the PPP negotiation does not
       succeed or if authentication fails.  If debugging is enabled at
       compile time, the debug option also causes other debugging
       messages to be logged.

       Debugging can also be enabled or disabled by sending a SIGUSR1
       signal to the pppd process.  This signal acts as a toggle.

EXIT STATUS         top

       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         top

       Pppd invokes scripts at various stages in its processing which
       can be used to perform site-specific ancillary processing.  These
       scripts are usually shell scripts, but could be executable code
       files instead.  Pppd does not wait for the scripts to finish
       (except for the ip-pre-up script).  The scripts are executed as
       root (with the real and effective user-id set to 0), so that they
       can do things such as update routing tables or run privileged
       daemons.  Be careful that the contents of these scripts do not
       compromise your system's security.  Pppd runs the scripts with
       standard input, output and error redirected to /dev/null, and
       with an environment that is empty except for some environment
       variables that give information about the link.  The environment
       variables that pppd sets are:

       DEVICE The name of the serial tty device being used.

       IFNAME The name of the network interface being used.

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

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

       LLLOCAL
              The Link-Local IPv6 address for the local end of the link.
              This is only set when IPV6CP has come up.

       LLREMOTE
              The Link-Local IPv6 address for the remote end of the
              link.  This is only set when IPV6CP has come up.

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

       SPEED  The baud rate of the tty device.

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

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

       For the ip-down and auth-down scripts, pppd also sets the
       following variables giving statistics for the connection:

       CONNECT_TIME
              The number of seconds from when the PPP negotiation
              started until the connection was terminated.

       BYTES_SENT
              The number of bytes sent (at the level of the serial port)
              during the connection.

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

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

       CALL_FILE
              The value of the call option.

       DNS1   If the peer supplies DNS server addresses, this variable
              is set to the first DNS server address supplied (whether
              or not the usepeerdns option was given).

       DNS2   If the peer supplies DNS server addresses, this variable
              is set to the second DNS server address supplied (whether
              or not the usepeerdns option was given).

       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-pre-up
              A program or script which is executed just before the ppp
              network interface is brought up.  It is executed with the
              same parameters as the ip-up script (below).  At this
              point the interface exists and has IP addresses assigned
              but is still down.  This can be used to add firewall rules
              before any IP traffic can pass through the interface.
              Pppd will wait for this script to finish before bringing
              the interface up, so this script should run quickly.

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

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

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

       /etc/ppp/ipv6-up
              Like /etc/ppp/ip-up, except that it is executed when the
              link is available for sending and receiving IPv6 packets.
              It is executed with the parameters

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

       /etc/ppp/ipv6-down
              Similar to /etc/ppp/ip-down, but it is executed when IPv6
              packets can no longer be transmitted on the link. It is
              executed with the same parameters as the ipv6-up script.

       /etc/ppp/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         top

       /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).

       /var/run/pppd2.tdb
              Database containing information about pppd processes,
              interfaces and links, used for matching links to bundles
              in multilink operation.  May be examined by external
              programs to obtain information about running pppd
              instances, the interfaces and devices they are using, IP
              address assignments, etc.  /etc/ppp/pap-secrets Usernames,
              passwords and IP addresses for PAP authentication.  This
              file should be owned by root and not readable or writable
              by any other user.  Pppd will log a warning if this is not
              the case.

       /etc/ppp/chap-secrets
              Names, secrets and IP addresses for CHAP/MS-CHAP/MS-CHAPv2
              authentication.  As for /etc/ppp/pap-secrets, this file
              should be owned by root and not readable or writable by
              any other user.  Pppd will log a warning if this is not
              the case.

       /etc/ppp/srp-secrets
              Names, secrets, and IP addresses for EAP authentication.
              As for /etc/ppp/pap-secrets, this file should be owned by
              root and not readable or writable by any other user.  Pppd
              will log a warning if this is not the case.

       ~/.ppp_pseudonym
              Saved client-side SRP-SHA1 pseudonym.  See the
              srp-use-pseudonym option for details.

       /etc/ppp/options
              System default options for pppd, read before user default
              options or command-line options.

       ~/.ppprc
              User default options, read before
              /etc/ppp/options.ttyname.

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

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

SEE ALSO         top

       chat(8), pppstats(8)

       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.

       RFC1990
              Sklower, K.; et al., The PPP Multilink Protocol (MP).
              August 1996.

       RFC2284
              Blunk, L.; Vollbrecht, J., PPP Extensible Authentication
              Protocol (EAP).  March 1998.

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

       RFC2945
              Wu, T., The SRP Authentication and Key Exchange System
              September 2000.

       draft-ietf-pppext-eap-srp-03.txt
              Carlson, J.; et al., EAP SRP-SHA1 Authentication Protocol.
              July 2001.

NOTES         top

       Some limited degree of control can be exercised over a running
       pppd process by sending it a signal from the list below.

       SIGINT, SIGTERM
              These signals cause pppd to terminate the link (by closing
              LCP), restore the serial device settings, and exit.  If a
              connector or disconnector process is currently running,
              pppd will send the same signal to its process group, so as
              to terminate the connector or disconnector process.

       SIGHUP This signal causes pppd to terminate the link, restore the
              serial device settings, and close the serial device.  If
              the persist or demand option has been specified, pppd will
              try to reopen the serial device and start another
              connection (after the holdoff period).  Otherwise pppd
              will exit.  If this signal is received during the holdoff
              period, it causes pppd to end the holdoff period
              immediately.  If a connector or disconnector process is
              running, pppd will send the same signal to its process
              group.

       SIGUSR1
              This signal toggles the state of the debug option.

       SIGUSR2
              This signal causes pppd to renegotiate compression.  This
              can be useful to re-enable compression after it has been
              disabled as a result of a fatal decompression error.
              (Fatal decompression errors generally indicate a bug in
              one or other implementation.)

AUTHORS         top

       Paul Mackerras (paulus@samba.org), based on earlier work by Drew
       Perkins, Brad Clements, Karl Fox, Greg Christy, and Brad Parker.

COPYRIGHT         top

       Pppd is copyrighted and made available under conditions which
       provide that it may be copied and used in source or binary forms
       provided that the conditions listed below are met.  Portions of
       pppd are covered by the following copyright notices:

       Copyright (c) 1984-2000 Carnegie Mellon University. All rights
       reserved.
       Copyright (c) 1993-2004 Paul Mackerras. All rights reserved.
       Copyright (c) 1995 Pedro Roque Marques.  All rights reserved.
       Copyright (c) 1995 Eric Rosenquist.  All rights reserved.
       Copyright (c) 1999 Tommi Komulainen.  All rights reserved.
       Copyright (C) Andrew Tridgell 1999
       Copyright (c) 2000 by Sun Microsystems, Inc.  All rights
       reserved.
       Copyright (c) 2001 by Sun Microsystems, Inc.  All rights
       reserved.
       Copyright (c) 2002 Google, Inc.  All rights reserved.

       The copyright notices contain the following statements.

       Redistribution and use in source and binary forms, with or
       without modification, are permitted provided that the following
       conditions are met:

       1. Redistributions of source code must retain the above copyright
          notice, this list of conditions and the following disclaimer.

       2. Redistributions in binary form must reproduce the above
       copyright
          notice, this list of conditions and the following disclaimer
       in
          the documentation and/or other materials provided with the
          distribution.

       3. The name "Carnegie Mellon University" must not be used to
          endorse or promote products derived from this software without
          prior written permission. For permission or any legal
          details, please contact
            Office of Technology Transfer
            Carnegie Mellon University
            5000 Forbes Avenue
            Pittsburgh, PA  15213-3890
            (412) 268-4387, fax: (412) 268-7395
            tech-transfer@andrew.cmu.edu

       3b. The name(s) of the authors of this software must not be used
       to
          endorse or promote products derived from this software without
          prior written permission.

       4. Redistributions of any form whatsoever must retain the
       following
          acknowledgements:
          "This product includes software developed by Computing
       Services
           at Carnegie Mellon University
       (http://www.cmu.edu/computing/)."
          "This product includes software developed by Paul Mackerras
           <paulus@samba.org>".
          "This product includes software developed by Pedro Roque
       Marques
           <pedro_m@yahoo.com>".
          "This product includes software developed by Tommi Komulainen
           <Tommi.Komulainen@iki.fi>".

       CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD
       TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
       MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON
       UNIVERSITY BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
       DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
       DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
       OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE
       USE OR PERFORMANCE OF THIS SOFTWARE.

       THE AUTHORS OF THIS SOFTWARE DISCLAIM ALL WARRANTIES WITH REGARD
       TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
       MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL THE AUTHORS BE
       LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY
       DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
       WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
       ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
       PERFORMANCE OF THIS SOFTWARE.

COLOPHON         top

       This page is part of the ppp (An implementation of the Point-to-
       Point Protocol (PPP)) project.  Information about the project can
       be found at ⟨https://ppp.samba.org/⟩.  If you have a bug report
       for this manual page, see
       ⟨https://github.com/paulusmack/ppp/issues⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://github.com/paulusmack/ppp⟩ on 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-06-19.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

                                                                 PPPD(8)

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