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ipppd

IPPPD(8)                  Linux System Administration                 IPPPD(8)



NAME
       ipppd - (ISDN) Point to Point Protocol daemon

SYNOPSIS
       /usr/sbin/ipppd [ options ] [ device ]

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

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

NOTES for (ISDN) IPPPD
       This  special  (ISDN) PPP daemon is a modified version of pppd and pro-
       vides synchronous PPP for ISDN connections.

       If you need asynchronous PPP over ISDN lines use pppd instead with  the
       ISDN character devices, see ttyI(4).

       The  ipppd  can handle multiple devices. This is necessary to link sev-
       eral connections together to one bundle.  ipppd should be started once.
       It  opens the devices and waits for connections.  If the connections is
       closed ipppd reopens the device automatically (the  device,  that's  it
       ...  not  the  link to the remote).  So you shouldn't kill the ipppd to
       close a link. Instead, trigger a hangup  on  the  netdevice  layer   by
       'isdnctrl hangup <device>'.

       The  facility  to configure the daemon via file /etc/ppp/ioptions.<dev-
       name> is disabled.  The 'file' option or the command line may  be  used
       for individual configuration.

       Do  not set the permissions of the program to 'setuid to root on execu-
       tion'. Call the daemon as root instead.  No common user should have the
       need to call the daemon!

OPTIONS
       <device>
              Communicate  over  the  named  device.   The  string  "/dev/" is
              prepended if necessary.  If no device name is given, or  if  the
              name  of  the  controlling terminal is given, ipppd will use the
              controlling terminal, and will not fork to  put  itself  in  the
              background.

       <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,  ipppd
              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.

       -ac    Disable  Address/Control  compression  negotiation (use default,
              i.e.  address/control field compression disabled).

       -all   Don't request or allow negotiation of any options  for  LCP  and
              IPCP (use default values).

       auth   Require  the peer to authenticate itself before allowing network
              packets to be sent or received.

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

       -bsdcomp
              Disables compression; ipppd will not request or  agree  to  com-
              press packets using the BSD-Compress scheme.

       callback <string>
              Request the peer to call back at the location given in <string>.
              Ususally this is a phone number, but it may be interpreted  dif-
              ferently (or ignored) depending on the callback-type option.  If
              <string> is the empty string, ipppd automatically tries to nego-
              tiate a callback type that does not need a location to be speci-
              fied.

       callback-delay <n>
              Callback delay for CBCP in seconds. If  callback  is  negotiated
              using  CBCP,  request  that  the peer waits at least <n> seconds
              before calling back. Ignored if callback is negotiated as speci-
              fied in RFC 1570. Legal range is 0..255, default is 5.

       callback-cbcp
              Enable callback negotiation via CBCB (default).

       -callback-cbcp
              Disable callback negotiation via CBCB.

       no-callback-cbcp
              Disable callback negotiation via CBCB.

       callback-cbcp-preferred
              If both CBCP and RFC 1570 style callback negotiation is enabled,
              CBCP is preferred (default)

       callback-rfc1570-preferred
              If both CBCP and RFC 1570 style callback negotiation is enabled,
              RFC 1570 style is preferred.

       callback-rfc1570
              Enable RFC 1570 style callback negotiation (default).

       -callback-rfc1570
              Disable RFC 1570 style callback negotiation.

       no-callback-rfc1570
              Disable RFC 1570 style callback negotiation (default).

       callback-type <n>
              Specifies  how  to  interpret  the  location identifier given as
              parameter of the callback option. Legal values are 0..4. A value
              of  0  means  that only callback types should be negotiated that
              need no extra location id. No location id is sent to the peer in
              this  case.  For RFC 1570 style callback negotiation, the values
              1..4 indicate how the peer should interpret the location identi-
              fier:  1  - id is a system specific dial string,  2 - id is used
              for database lookup by the peer, 3 - id is a phone number, and 4
              id  is a name. For CBCP callback negotiation, the location id is
              always interpreted as a phone number.

       -ccp   Necessary for a few netblazers on the remote side.

       noccp  same as -ccp

       +chap  Require the peer to  authenticate  itself  using  CHAP  [Crypto-
              graphic Handshake Authentication Protocol] authentication.

       -chap  Don't agree to authenticate using CHAP.

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

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

       chap-restart <n>
              Set  the CHAP restart interval (retransmission timeout for chal-
              lenges) to <n> seconds (default 3).

       debug  Increase debugging level (same as -d).  If this option is given,
              ipppd  will  log  the  contents  of  all control packets sent or
              received in a readable form.  The  packets  are  logged  through
              syslog  with  facility daemon and level debug.  This information
              can be directed to a file by setting up /etc/syslog.conf  appro-
              priately (see syslog.conf(5)).

       -d     Increase debugging level (same as the debug option).

       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.

       -defaultroute
              Disable  the  defaultroute option.  The system administrator who
              wishes to prevent users from creating default routes with  ipppd
              can  do so by placing this option in the /etc/ppp/ioptions file.

       deldefaultroute
              Replace default route if it already exists.  Together  with  the
              option  defaultroute,  this  will  replace  any existing default
              route by a new one through this ipppd's interface when it  comes
              up.

       -detach
              Don't  fork to become a background process (otherwise ipppd will
              do so if a serial device other than its controlling terminal  is
              specified).

       domain <d>
              Append  the domain name <d> to the local host name for authenti-
              cation purposes.  For example, if gethostname() returns the name
              porsche,    but    the    fully   qualified   domain   name   is
              porsche.Quotron.COM, you would use the domain option to set  the
              domain name to Quotron.COM.

       file <f>
              Read options from file <f> (the format is described below).

       -ip    Disable  IP  address  negotiation.   If this option is used, the
              remote IP address must be specified with an option on  the  com-
              mand line or in an options file.

       +ip-protocol
              Enable the IPCP and IP protocols. This is the default condition.
              This option is only needed if the default setting is  -ip-proto-
              col.

       -ip-protocol
              Disable  the  IPCP and IP protocols. This should only be used if
              you know that you are using a client which only understands  IPX
              and you don't want to confuse the client with the IPCP protocol.

       +ipx-protocol
              Enable the IPXCP and IPX protocols. This is the  default  condi-
              tion  if your kernel supports IPX. This option is only needed if
              the default setting is -ipx-protocol. If your  kernel  does  not
              support IPX then this option will have no effect.

       -ipx-protocol
              Disable the IPXCP and IPX protocols. This should only be used if
              you know that you are using a client which only  understands  IP
              and  you  don't want to confuse the client with the IPXCP proto-
              col.

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

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

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

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

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

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

       ipx-network <n>
              Set  the IPX network number in the IPXCP configure request frame
              to <n>. There is no valid default. If this option is not  speci-
              fied  then  the network number is obtained from the peer. If the
              peer does not have the network number, the IPX protocol will not
              be  started. This is a hexadecimal number and is entered without
              any leading sequence such as 0x. It is  related  to  the  ipxcp-
              accept-network option.

       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, to the maximum
              of  ten  significant digits. The node numbers on the ipx-network
              must be unique. There is no valid default. If this option is not
              specified  then  the node number is obtained from the peer. This
              option is a related to the ipxcp-accept-local and  ipxcp-accept-
              remote options.

       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.  Use  a
              comma-serperated  list if you want to specify more than one pro-
              tocol.  The 'none' option (0)  may  be  specified  as  the  only
              instance  of  ipx-routing.  The  values may be 0 for NONE, 2 for
              RIP/SAP, and 4 for NLSP.

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

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

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

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

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

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

       kdebug n
              Enable debugging code in the kernel-level PPP driver.  The argu-
              ment  n  is a number which is the sum of the following values: 1
              to enable general debug messages, 2 to request that the contents
              of  received  packets be printed, and 4 to request that the con-
              tents of transmitted packets be printed.

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

       lcp-echo-interval <n>
              If  this  option  is  given, ipppd will send an LCP echo-request
              frame to the peer every n seconds.  With Linux, the echo-request
              is  sent  when no packets have been received from the peer for 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  con-
              nected.

       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).

       lock   Specifies that ipppd should create a UUCP-style  lock  file  for
              the serial device to ensure exclusive access to the device.

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

       -mn    Disable magic number negotiation.  With this option, ipppd  can-
              not detect a looped-back line.

       +mp    enables MPPP negotiation

       mru <n>
              Set the MRU [Maximum Receive Unit] value to <n> for negotiation.
              ipppd will ask the peer to send packets  of  no  more  than  <n>
              bytes.   The minimum MRU value is 128.  The default MRU value is
              1500.  A value of 296 is recommended for slow  links  (40  bytes
              for TCP/IP header + 256 bytes of data).

       -mru   Disable  MRU  [Maximum  Receive  Unit]  negotiation.   With this
              option, ipppd will use the default MRU value of 1500 bytes.

       ms-dns <n>
              This option sets the IP address or addresses for the Domain Name
              Server. It is used by Microsoft Windows clients. The primary DNS
              address is specified by the first instance of the ms-dns option.
              The secondary is specified by the second instance.

       ms-get-dns
              Implements  the client side of RFC1877.  If ipppd is acting as a
              client to a server that implements RFC1877 such as one  intended
              to  be  used  with Microsoft Windows clients, this option allows
              ipppd to obtain one or two DNS (Domain  Name  Server)  addresses
              from  the  server.  It does not do anything with these addresses
              except put them in the environment  (MS_DNS1  MS_DNS2)  that  is
              passed  to scripts.  For compatibility with the async pppd, DNS1
              DNS2 environment variables are also set. A sample resolv.conf is
              created  in  /etc/ppp/resolv.conf.   The  /etc/ppp/ip-up  script
              should use this information to perform  whatever  adjustment  is
              necessary.  Note: RFC1877 is a horrible protocol layering viola-
              tion, the correct approach would be to use DHCP after  the  IPCP
              phase.

       ms-get-wins
              As  ms-get-dns  but  for  WINS  (Windows Internet Name Services)
              server  addresses.  Environment  variables  are   MS_WINS1   and
              MS_WINS2.

       mtu <n>
              Set  the  MTU  [Maximum Transmit Unit] value to <n>.  Unless the
              peer requests a smaller value via MRU  negotiation,  ipppd  will
              request  that the kernel networking code send data packets of no
              more than n bytes through the PPP network interface.

       name <n>
              Set the name of the local system for authentication purposes  to
              <n>.

       netmask <n>
              Set  the  interface netmask to <n>, a 32 bit netmask in "decimal
              dot" notation (e.g. 255.255.255.0).  If this  option  is  given,
              the  value  specified  is  ORed  with  the default netmask.  The
              default netmask is chosen based  on  the  negotiated  remote  IP
              address; it is the appropriate network mask for the class of the
              remote IP address, ORed with the netmasks for any non  point-to-
              point  network  interfaces  in  the system which are on the same
              network.

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

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

       -p     Same as the passive option.

       +pap   Require the peer to authenticate itself using PAP.

       -pap   Don't agree to authenticate using PAP.

       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  ipppd  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  ipppd  will  wait for the peer to
              authenticate itself with PAP to <n> seconds (0 means no  limit).

       -pc    Disable  protocol  field  compression  negotiation (use default,
              i.e.  protocol field compression disabled).

       pidfile <filename>
              Use <filename> instead of /var/run/ipppd.pid

       pred1comp
              Attempt to request that the peer send the  local  system  frames
              which  have  been compressed by the Predictor-1 compression. The
              compression protocols must be loaded  or  this  option  will  be
              ignored.

       -pred1comp
              Do  not accept Predictor-1 comprssion, even if the peer wants to
              send this type of compression and support has  been  defined  in
              the kernel.

       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.

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

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

       set_userip
              You may define valid IPs in /etc/ppp/useriptab

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

       +ua <p>
              Agree to authenticate using PAP [Password Authentication  Proto-
              col]  if requested by the peer, and use the data in file <p> for
              the user and password to send to the peer. The file contains the
              remote  user name, followed by a newline, followed by the remote
              password, followed by a newline.  This option is obsolescent.

       usefirstip
              Gets the remote address from the first entry in  the  auth  file
              (if there is an IP address entry). This address should be a full
              IP address not an address  from  a  masked  area.   Ipppd  calls
              'gethostbyname()'  and negotiates the result.  IP from auth file
              will overwrite the remote address  gotten  from  the  interface.
              'usefirstip' is UNTESTED!

       usehostname
              Enforce  the use of the hostname as the name of the local system
              for authentication purposes (overrides the name option).

       usepeerdns
              Same as ms-get-dns for compatibility with async pppd.

       user <u>
              Set the user name to use for authenticating  this  machine  with
              the peer using PAP to <u>.

       useifip
              will get (if not set to 0.0.0.0) the IP address for the negotia-
              tion from the attached network-interface.  (also: ipppd will try
              to negotiate 'pointopoint' IP as remote IP) interface address ->
              local IP pointopoint address -> remote IP

       -vj    Disable negotiation of Van Jacobson style TCP/IP header compres-
              sion (use default, i.e. no compression).

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

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

OPTIONS FILES
       Options can be taken from files as well as  the  command  line.   ipppd
       reads  options  from  the  file /etc/ppp/ioptions before looking at the
       command line.  An options file is parsed into a series of words, delim-
       ited  by whitespace.  Whitespace can be included in a word by enclosing
       the word in quotes (").  A backslash (\) quotes the  following  charac-
       ter.  A hash (#) starts a comment, which continues until the end of the
       line.

AUTHENTICATION
       ipppd 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.  In part this is provided by the /etc/ppp/ioptions file, where
       the administrator can place options to require authentication  whenever
       ipppd  is run, and in part by the PAP and CHAP secrets files, where the
       administrator can restrict the set of  IP  addresses  which  individual
       users may use.

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

       Authentication is based on secrets, which  are  selected  from  secrets
       files  (/etc/ppp/pap-secrets  for PAP, /etc/ppp/chap-secrets for CHAP).
       Both secrets files have the same format, and both can store secrets for
       several  combinations  of server (authenticating peer) and client (peer
       being authenticated).  Note that ipppd can be both a server and client,
       and  that  different  protocols  can  be  used in the two directions if
       desired.

       A secrets file is parsed into words as for a options file.  A secret is
       specified  by  a  line containing at least 3 words, in the order client
       name, server name, secret.  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, it is assumed that any  IP  address
       is  OK;  to  disallow  all IP addresses, use "-".  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, ipppd takes the  best  match,  i.e.
       the match with the fewest wildcards.

       Thus  a  secrets  file  contains both secrets for use in authenticating
       other hosts, plus secrets which we use for authenticating ourselves  to
       others.   Which  secret to use is chosen based on the names of the host
       (the `local name') and its peer (the `remote name').  The local name is
       set as follows:

       if the usehostname option is given,
          then the local name is the hostname of this machine (with the domain
          appended, if given)

       else if the name option is given,
          then use the argument of the first name option seen

       else if the local IP address is specified with a hostname,
          then use that name

       else use the hostname of this machine (with  the  domain  appended,  if
       given)

       When authenticating ourselves using PAP, there  is  also  a  `username'
       which is the local name by default, but can be set with the user option
       or the +ua option.

       The remote name is set as follows:

       if the remotename option is given,
          then use the argument of the last remotename option seen

       else if the remote IP address is specified with a hostname,
          then use that host name

       else the remote name is the null string "".

       Secrets are selected from the PAP secrets file as follows:

       * For authenticating the peer, look for a secret with client  ==  user-
         name  specified  in the PAP authenticate-request, and server == local
         name.

       * For authenticating ourselves to the peer,  look  for  a  secret  with
         client == our username, server == remote name.

       When authenticating the peer with PAP, a secret of "" matches any pass-
       word supplied by the peer.  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  the  papcrypt  option is given, the first (unen-
       crypted) comparison is omitted, for better security.

       If the login option was specified, the username and password  are  also
       checked  against the system password database.  Thus, the system admin-
       istrator 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  "", to avoid the need to have the same
       secret in two places.

       Secrets are selected from the CHAP secrets file as follows:

       * For authenticating the peer, look for a secret with  client  ==  name
         specified in the CHAP-Response message, and server == local name.

       * For  authenticating  ourselves  to  the  peer, look for a secret with
         client == local name, and server == name specified in the  CHAP-Chal-
         lenge message.

       Authentication  must  be  satisfactorily  completed before IPCP (or any
       other Network Control Protocol)  can  be  started.   If  authentication
       fails,  ipppd will terminated the link (by closing LCP).  If IPCP nego-
       tiates an unacceptable IP address for the remote  host,  IPCP  will  be
       closed.  IP packets can only be sent or received when IPCP is open.

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

ROUTING
       When  IPCP negotiation is completed successfully, ipppd will inform the
       kernel of the local and remote IP  addresses  for  the  ppp  interface.
       This  is  sufficient  to  create  a host route to the remote end of the
       link, which will enable the peers to exchange IP  packets.   Communica-
       tion  with  other  machines  generally requires further modification to
       routing tables and/or ARP (Address  Resolution  Protocol)  tables.   In
       some  cases  this will be done automatically through the actions of the
       routed or gated daemons, but in most cases some further intervention is
       required.

       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 ipppd to
       create such a default route when IPCP comes up, and delete it when  the
       link is terminated.

       In some cases it is desirable to use proxy ARP, for example on a server
       machine connected to a LAN, in order to allow other hosts  to  communi-
       cate  with  the  remote host.  The proxyarp option causes ipppd 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,  ipppd  creates  a  permanent,
       published  ARP  entry  with  the  IP address of the remote host and the
       hardware address of the network interface found.

DIAGNOSTICS
       Messages are sent to  the  syslog  daemon  using  facility  LOG_DAEMON.
       (This  can  be  overriden  by  recompiling ipppd with the macro LOG_PPP
       defined as the desired facility.)  In order to see the error and  debug
       messages,  you  will  need to edit your /etc/syslog.conf file to direct
       the messages to the desired output device or file.

       The debug option causes the contents of all  control  packets  sent  or
       received  to  be  logged,  that is, all LCP, PAP, CHAP or IPCP packets.
       This can be useful if the PPP negotiation does not succeed.  If  debug-
       ging  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  to  the
       ipppd process.  This signal acts as a toggle.

FILES
       /var/run/ipppd.pid
              Process-ID for ipppd process on ppp interface unit n.

       /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

              and with its standard input, output and error streams redirected
              to /dev/null.

              This program or script is executed with the same real and effec-
              tive user-ID as ipppd, that is, at least the  effective  user-ID
              and  possibly the real user-ID will be root.  This is so that it
              can be used to manipulate routes, run privileged  daemons  (e.g.
              sendmail),   etc.    Be   careful   that  the  contents  of  the
              /etc/ppp/ip-up and /etc/ppp/ip-down scripts  do  not  compromise
              your system's security.

       /etc/ppp/ip-down
              A program or script which is executed when the link is no longer
              available for sending and receiving IP packets.  This script can
              be  used  for  undoing the effects of the /etc/ppp/ip-up script.
              It is invoked with the same parameters as the ip-up script,  and
              the  same  security  considerations  apply, since it is executed
              with the same effective and real user-IDs as ipppd.

       /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 ipppd-pid

              and with its standard input, output and error streams redirected
              to /dev/null.

              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

              This program or script is executed with the same real and effec-
              tive user-ID as ipppd, that is, at least the  effective  user-ID
              and  possibly the real user-ID will be root.  This is so that it
              can be used to manipulate routes, run privileged  daemons  (e.g.
              ripd), etc.  Be careful that the contents of the /etc/ppp/ipx-up
              and /etc/ppp/ipx-down scripts do not  compromise  your  system's
              security.

       /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 with the same parameters  as  the  ipx-up
              script,  and the same security considerations apply, since it is
              executed with the same effective and real user-IDs as ipppd.

       /etc/ppp/auth-up
              This program or script is executed after successful  authentica-
              tion  with the following parameters: interface name, authentica-
              tion user name, username of  ipppd,  devicename,  speed,  remote
              number

       /etc/ppp/auth-down
              This  program  or  script is executed after a disconnection with
              the following parameters: interface  name,  authentication  user
              name, username of ipppd, devicename, speed, remote number

       /etc/ppp/auth-fail
              This  program or script is executed after a authentication fail-
              ure with the following parameters: interface  name,  authentica-
              tion  user  name,  username  of ipppd, devicename, speed, remote
              number, failure reason
               Valid reasons are:
                1 = Timeout during pap auth
                2 = pap protocol rejected
                3 = pap secrets invalid
                9 = Timeout during chap auth
               10 = chap protocol rejected
               11 = chap secrets invalid

       /etc/ppp/pap-secrets
              Usernames, passwords and IP addresses for PAP authentication.

       /etc/ppp/chap-secrets
              Names, secrets and IP addresses for CHAP authentication.

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

SEE ALSO
       ttyI(4), isdnctrl(8), ipppstats(8),

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

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

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

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

       RFC1548
              Simpson, W.A.  The Point-to-Point Protocol (PPP).   1993  Decem-
              ber.

       RFC1549
              Simpson, W.A.  PPP in HDLC Framing.  1993 December

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

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

       SIGHUP This  signal  causes  ipppd  to  terminate the link, restore the
              serial device settings, and close the  serial  device.   If  the
              persist  option has been specified, ipppd will try to reopen the
              serial device and start  another  connection.   Otherwise  ipppd
              will exit.

       SIGUSR2
              This  signal  causes ipppd to renegotiate compression.  This can
              be useful to re-enable compression after it has been disabled as
              a  result of a fatal decompression error.  With the BSD Compress
              scheme, fatal decompression errors generally indicate a  bug  in
              one or other implementation.

AUTHORS
       Originally  written  by  Drew  Perkins,  Brad  Clements, Karl Fox, Greg
       Christy, Brad Parker, Paul Mackerras <paulus@cs.anu.edu.au> for (origi-
       nal) pppd.

       Changes  for  ipppd  by  Klaus  Franken  <kfr@suse.de> and Michael Hipp
       <Michael.Hipp@student.uni-tuebingen.de>.

       Removal  of  pppd  specific  options  and  polish   by   Frank   Elsner
       <Elsner@zrz.TU-Berlin.DE>.



isdn4k-utils-3.1pre4              2000/07/25                          IPPPD(8)