Point to Point Protocol for OS/2 TCP/IP 2.0: Difference between revisions

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==NAME==
:ppp - Point to Point Protocol for OS/2 TCP/IP 2.0


NAME
==SYNOPSIS==
      ppp - Point to Point Protocol for OS/2 TCP/IP 2.0
:ppp [ options ] [ com port ] [ speed ]


SYNOPSIS
==DESCRIPTION==
      ppp [ options ] [ com port ] [ speed ]
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 networklayer protocols.


DESCRIPTION
The encapsulation scheme is provided by an OS/2 Ring 3 driver and an interface to the TCP/IP kernel. PPP provides the basic LCP, authentication support, and an NCP for establishing and configuring the Internet Protocol (IP) (called the IP Control Protocol, IPCP).


The  Point-to-Point  Protocol  (PPP) provides a method for transmitting datagrams over serial  point-to-point  links.
==FREQUENTLY USED OPTIONS==
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  networklayer protocols.
;<com port>:Communicate over the named com device. If no device name is given, ppp will use com1.
 
;<speed>:Set the async port line speed to <speed>.
The  encapsulation  scheme  is  provided by an OS/2 Ring 3
;asyncmap <map>:Set the async character map to <map>. This map describes which control characters cannot be successfully received over the serial line. ppp will ask the peer to send these characters as a 2-byte "escape" sequence. The argument is a 32 bit hex number with each bit representing a character to escape. Bit 0 (00000001) represents the character 0x00; bit 31 (80000000) represents the character 0x1f or ^_. The default asyncmap is 0. If multiple asyncmap options are given, the values are ORed together.
driver and an interface to the TCP/IP  kernel.  PPP  provides  the  basic  LCP, authentication support, and an NCP
;auth:Require the peer to authenticate itself before allowing network packets to be sent or received.
for establishing and  configuring  the  Internet  Protocol
;connect <command>:Use the executable or shell command specified by <command> to set up the serial line. This script would typically use the "slattach" program or a REXX command file to dial the modem and start a remote ppp session.
(IP) (called the IP Control Protocol, IPCP).
;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.
 
;file <filename>:Read options from file <filename> (the format is described below).
FREQUENTLY USED OPTIONS
;help (-?):Display ppp usage information for the most common options.
      <com port>
;mru <n>:Set the MRU [Maximum Receive Unit] value to <n> for negotiation. ppp 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 interactive links (40 bytes for TCP/IP header + 256 bytes of data).
              Communicate over the named com device.   If no
;netmask <n>:Set the interface netmask to <n>, a 32 bit netmask in "decimal dot" notation (e.g. 255.255.255.0).
              device name is given, ppp will use com1.
;passive:Enables the "passive" option in the LCP. With this option, ppp will attempt to initiate a connection; if no reply is received from the peer, ppp will then just wait passively for a valid LCP packet from the peer (instead of exiting, as it does without this option).
 
;restart:Restart LCP negotiation after link termination. This overrides the default behavior of terminating the ppp driver after disconnect.
      <speed>
;rtscts:Use hardware flow control (i.e. RTS/CTS) to control the flow of data on the serial port.
              Set the async port line speed to <speed>.
;silent:With this option, ppp will not transmit LCP packets to initiate a connection until a valid LCP packet is received from the peer.
 
      asyncmap <map>
              Set the async character map to <map>.   This map
              describes which control characters cannot be suc-
              cessfully received over the serial line. ppp will
              ask the peer to send these characters as a 2-byte
              "escape" sequence. The argument is a 32 bit hex
              number with each bit representing a character to
              escape. Bit 0 (00000001) represents the character
              0x00; bit 31 (80000000) represents the character
              0x1f or ^_. The default asyncmap is 0. If multi-
              ple asyncmap options are given, the values are ORed
              together.
 
      auth   Require the peer to authenticate itself before
              allowing network packets to be sent or received.
 
      connect <command>
              Use the executable or shell command specified by
              <command> to set up the serial line.   This script
              would typically use the "slattach" program or a
              REXX command file to dial the modem and start a
              remote ppp session.
 
      defaultroute
              Add a default route to the system routing tables,
            using the peer as the gateway, when IPCP negotia-
              tion  is successfully completed.   This entry is
              removed when the PPP connection is broken.
 
      file <filename>
              Read options from file <filename> (the format is
              described below).
 
      help (-?)
              Display ppp usage information for the most common
              options.
 
      mru <n>
              Set the MRU [Maximum Receive Unit] value to <n> for
              negotiation. ppp 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 interactive links (40
              bytes for TCP/IP header + 256 bytes of data).
 
      netmask <n>
              Set the interface netmask to <n>, a 32 bit netmask
              in "decimal dot" notation (e.g. 255.255.255.0).
 
      passive
              Enables the "passive" option in the LCP. With this
              option, ppp will attempt to initiate a connection;
              if no reply is received from the peer, ppp will
              then just wait passively for a valid LCP packet
              from the peer (instead of exiting, as it does with-
              out this option).
 
      restart
              Restart LCP negotiation after link termination.
              This overrides the default behavior of terminating
              the ppp driver after disconnect.
 
      rtscts Use hardware flow control (i.e. RTS/CTS) to control
              the flow of data on the serial port.
 
      silent With this option, ppp will not transmit LCP packets
              to initiate a connection until a valid LCP packet
              is received from the peer.
 
OTHER OPTIONS
      <local_IP_address>:<remote_IP_address>
              Set the local and/or remote interface IP addresses.
              Either one may be omitted.  The IP addresses can be
              specified with a host  name  or  in  "decimal  dot"
              notation  (e.g.  "150.203.23.247").  The  default
              local address is the first IP address of  the  sys-
              tem.  The remote address will be obtained from the
              peer if not specified in any option.  Thus, in sim-
              ple cases, this option is not required.
 
      -all  Don't  request  or allow negotiation of any options
              for LCP and IPCP, use default values.
 
      -ac    Disable  Address/Control  compression  negotiation
              (use default, i.e.  disabled).
 
      -am    Disable  asyncmap  negotiation  (use  default, i.e.
              0xffffffff).
 
      -as <n>
              Same as asyncmap <n>
 
      -d    Increase debugging level.
 
      -ip    Disable IP address negotiation.  With this  option,
              the  remote  IP  address  must be specified with an
              option on the command line or in an options file.
 
      -mn    Disable  magic  number  negotiation.    With  this
              option, ppp cannot detect a looped-back line.
 
      -mru  Disable MRU [Maximum Receive Unit] negotiation (use
              default, i.e. 1500).
 
      -p    Same as the passive option.
 
      -pc    Disable protocol field compression negotiation (use
              default, i.e. disabled).
 
;<PRE>+ua <p></PRE>
 
Agree to authenticate using PAP [Password Authentication Protocol] 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.
 
      +pap  Require the peer to authenticate itself using  PAP.
 
      -pap  Don't agree to authenticate using PAP.
 
      +chap  Require  the peer to authenticate itself using CHAP
              [Cryptographic Handshake  Authentication  Protocol]
              authentication.
 
      -chap  Don't agree to authenticate using CHAP.
 
      -vj    Disable negotiation of Van Jacobson style IP header
              compression (use default, i.e. no compression).
 
      debug  Increase debugging level (same as -d ).
 
 
;<PRE>domain <d></PRE>
              Append the domain name <d> to the local  host  name
              for authentication purposes.  For example, if geth-
              ostname() returns the name foobar,  but  the  fully
              qualified  domain name is foobar.IBM.COM, you would
              use the domain option to set  the  domain  name  to
              IBM.COM.
 
      exit  Causes  the  ppp  driver  to terminate on detecting
              loss of the modem Data Carrier Detect (DCD) signal.
 
      idle <n>
              Set  the  amount of inactivity time (no IP traffic)
              until the ppp driver hangs up the connection.
 
      local  Don't use modem control lines.
 
      name <n>
              Set the name of the local system for authentication
              purposes to <n>.


==OTHER OPTIONS==
<local_IP_address>:<remote_IP_address>
:Set the local and/or remote interface IP addresses. Either one may be omitted. The IP addresses can be specified with a host name or in "decimal dot" notation (e.g. "150.203.23.247"). The default local address is the first IP address of the system. The remote address will be obtained from the peer if not specified in any option. Thus, in simple cases, this option is not required.
;-all:Don't request or allow negotiation of any options for LCP and IPCP, use default values.
;-ac:Disable Address/Control compression negotiation (use default, i.e. disabled).
;-am:Disable asyncmap negotiation (use default, i.e. 0xffffffff).
;-as <n>:Same as asyncmap <n>
;-d:Increase debugging level.
;-ip:Disable IP address negotiation. With this option, the remote IP address must be specified with an option on the command line or in an options file.
;-mn:Disable magic number negotiation. With this option, ppp cannot detect a looped-back line.
;-mru:Disable MRU [Maximum Receive Unit] negotiation (use default, i.e. 1500).
;-p:Same as the passive option.
;-pc:Disable protocol field compression negotiation (use default, i.e. disabled).
;<PRE>+ua <p></PRE>:Agree to authenticate using PAP [Password Authentication Protocol] 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.
;+pap:Require the peer to authenticate itself using PAP.
;-pap:Don't agree to authenticate using PAP.
;+chap:Require the peer to authenticate itself using CHAP [Cryptographic Handshake Authentication Protocol] authentication.
;-chap:Don't agree to authenticate using CHAP.
;-vj:Disable negotiation of Van Jacobson style IP header compression (use default, i.e. no compression).
;debug:Increase debugging level (same as -d ).
;<PRE>domain <d></PRE>:Append the domain name <d> to the local host name for authentication purposes. For example, if gethostname() returns the name foobar, but the fully qualified domain name is foobar.IBM.COM, you would use the domain option to set the domain name to IBM.COM.
exit
:Causes the ppp driver to terminate on detecting loss of the modem Data Carrier Detect (DCD) signal.
idle <n>
:Set the amount of inactivity time (no IP traffic) until the ppp driver hangs up the connection.
local
:Don't use modem control lines.
name <n>
:Set the name of the local system for authentication purposes to <n>.


;<PRE>user <u></PRE>
;<PRE>user <u></PRE>
              Set the user name to use for authenticating this
:Set the user name to use for authenticating this machine with the peer using PAP to <PRE><u></PRE>.
              machine with the peer using PAP to <u>.
;usehostname
:Enforce the use of the hostname as the name of the local system for authentication purposes (overrides the name option).
remotename <n>
:Set the assumed name of the remote system for authentication purposes to <n>.
proxyarp
:Add an entry to this system's ARP [Address Resolution Protocol] table with the IP address of the peer and the Token-Ring/Ethernet address of this system.
login
:Use the system password database for authenticating the peer using PAP.
secret <secret>
:Use the secret <secret> for PAP and CHAP authentication with the peer.
lcp-restart <n>
:Set the LCP restart interval (retransmission timeout) to <n> seconds (default 3).
lcp-max-terminate <n>
:Set the maximum number of LCP terminate-request transmissions to <n> (default 3).
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).
ipcp-restart <n>
:Set the IPCP restart interval (retransmission timeout) to <n> seconds (default 5 seconds).
ipcp-max-terminate <n>
:Set the maximum number of IPCP terminate-request transmissions to <n> (default 3).
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).
pap-restart <n>
:Set the PAP restart interval (retransmission timeout) to <n> seconds (default 5 seconds).
pap-max-authreq <n>
:Set the maximum number of PAP authenticate-request transmissions to <n> (default 10).
chap-restart <n>
:Set the CHAP restart interval (retransmission timeout for challenges) to <n> seconds (default 5 seconds).
chap-max-challenge <n>
:Set the maximum number of CHAP challenge transmissions to <n> (default 10).
chap-interval <n>
:If this option is given, ppp will rechallenge the peer every <n> seconds.


      usehostname
==OPTIONS FILES==
              Enforce the use of the hostname as the name of the
Options can be taken from files as well as the command line. ppp reads options from the files $ETC/ppp.cfg and $HOME/ppprc before looking at the command line. 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 quotes ("). A backslash (\) quotes the following character. A hash (#) starts a comment, which continues until the end of the line.
              local system for authentication purposes (overrides
              the name option).


      remotename <n>
==AUTHENTICATION==
              Set the assumed  name  of the  remote  system  for
The PAP and CHAP secrets files can be setup to restrict the set of IP addresses which individual users may use.
              authentication purposes to <n>.


      proxyarp
The default behaviour of ppp is to agree to authenticate if requested, and to not require authentication from the peer. However, ppp will not agree to authenticate itself with a particular protocol if it has no secrets which could be used to do so.
              Add  an entry to this system's ARP [Address Resolu-
              tion Protocol] table with the IP  address  of  the
              peer and  the  Token-Ring/Ethernet address of this
              system.


      login  Use the system password database for authenticating
Authentication is based on secrets, which are selected from secrets files, $ETC/pap.sct for PAP, and $ETC/chap.sct 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 ppp can be both a server and client, and that different protocols can be used in the two directions if desired.
              the peer using PAP.


      secret <secret>
A secrets file is parsed into words similar to the options file. A secret is specified by a line containing at least 3 words, in the order client, server, secret. Any following words on the same line are taken to be a list of acceptable IP addresses for that client. If there are
              Use  the secret <secret> for PAP and CHAP authenti-
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 (wildcard). When selecting a secret, ppp takes the best match, i.e. the match with the fewest wildcards.
              cation with the peer.


      lcp-restart <n>
A secrets file contains both secrets for use in authenticating other hosts, plus secrets which can be used 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:
              Set the LCP restart interval (retransmission  time-
: if the usehostname option is given, then the local name is the hostname of this machine (with the domain appended, if supplied)
              out) to <n> seconds (default 3).
: 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.


      lcp-max-terminate <n>
The remote name is set as follows:
              Set  the maximum  number  of LCP terminate-request
: if the remotename option is given, then use the argument of the last remotename option seen
              transmissions to <n> (default 3).
: else if the remote IP address is specified with a hostname, then use that host name
: else the remote name is the null string "".


      lcp-max-configure <n>
Secrets are selected from the PAP secrets file as follows:
              Set the maximum  number  of  LCP  configure-request
* For authenticating the peer, look for a secret with client == username specified in the PAP authenticate-request, and server == local name.
              transmissions to <n> (default 10).
* For authenticating ourselves to the peer, look for a secret with client == our username, server == remote name.


      lcp-max-failure <n>
When authenticating the peer with PAP, a secret of "" matches any password 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 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.
              Set  the maximum  number  of LCP  configure-NAKs
              returned before starting to send  configure-Rejects
              instead to <n> (default 10).


      ipcp-restart <n>
Secrets are selected from the CHAP secrets file as follows:
              Set the IPCP restart interval (retransmission time-
* For authenticating the peer, look for a secret with client == name specified in the CHAP-Response message, and server == local name.
              out) to <n> seconds (default 5 seconds).
** For authenticating ourselves to the peer, look for a secret with client == local name, and server == name specified in the CHAP-Challenge message.


      ipcp-max-terminate <n>
Authentication must be satisfactorily completed before IPCP (or any other Network Control Protocol) can be started. If authentication fails, ppp will terminated the link by closing LCP. If IPCP negotiates an unacceptable IP address for the remote host, IPCP will be closed. IP
              Set the maximum number  of  IPCP terminate-request
packets can only be sent or received when IPCP is open.
              transmissions to <n> (default 3).


      ipcp-max-configure <n>
==ROUTING==
              Set  the maximum  number of IPCP configure-request
When IPCP negotiation is completed successfully, ppp will inform the TCP/IP 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 some cases this may be done automatically through the actions of command scripts, but in most cases some further intervention is required.
              transmissions to <n> (default 10).


      ipcp-max-failure <n>
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 ppp to create such a default route when IPCP comes up, and delete it when the link is terminated.
              Set  the maximum  number  of IPCP  configure-NAKs
              returned  before starting to send configure-Rejects
              instead to <n> (default 10).


      pap-restart <n>
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 ppp 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, ppp creates a permanent, published ARP entry with the IP address of the remote host and the hardware address of the network interface found.
              Set the PAP restart interval (retransmission  time-
              out) to <n> seconds (default 5 seconds).


      pap-max-authreq <n>
==EXAMPLES==
              Set  the maximum number of PAP authenticate-request
In the simplest case, you can connect the serial ports of two machines via a NULL modem cable and issue a command like
              transmissions to <n> (default 10).
ppp com1 38400 passive
to each machine.


      chap-restart <n>
The process of logging in to a host machine and starting ppp can be automated by using the connect option to run slattach or a REXX script, for example:
              Set the CHAP restart interval (retransmission time-
ppp com1 38400 connect "slattach AT OK ATDT999-9999
              out for challenges) to <n> seconds (default 5 sec-
  CONNECT login: foobar Password: password"
              onds).
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). Don't use an rlogin in the path - many implementations are not transparent; they will remove the sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the stream.


      chap-max-challenge <n>
==DIAGNOSTICS==
              Set the maximum number of CHAP challenge  transmis-
Messages are logged to both the console and the $ETC/ppp<n>.log file.
              sions to <n> (default 10).


      chap-interval <n>
==FILES==
              If this option is given, ppp will rechallenge the
$ETC/ppp<n>.pid
              peer every <n> seconds.
:Process-ID for ppp process on ppp interface unit n.
  $ETC/pap.sct
:Usernames, passwords and IP addresses for PAP authentication.
  $ETC/chap.sct
:Names, secrets and IP addresses for CHAP authentication.
$ETC/ppp.cfg
:System default options for ppp, read before user default options or command-line options.
$HOME/ppprc
:User default options, read before command-line options.


OPTIONS FILES
==SEE ALSO==
      Options can be taken from files as  well  as  the  command
RFC1144
      line.   ppp reads options from the files $ETC/ppp.cfg and
:Jacobson, VCompressing TCP/IP headers for low-speed serial links. 1990 February.
      $HOME/ppprc before  looking  at  the  command  line.   An
RFC1321
      options  file  is parsed into a series of words, delimited
:Rivest, R. The MD5 Message-Digest Algorithm. 1992 April.
      by whitespaceWhitespace can be included in  a  word  by
RFC1331
      enclosing  the word in quotes (").  A backslash (\) quotes
:Simpson, W.APoint-to-Point Protocol (PPP) for the transmission of multi-protocol datagrams over point-to-point links. 1992 May.
      the following character. A hash (#)  starts  a  comment,
RFC1332
      which continues until the end of the line.
:McGregor, GPPP Internet Protocol Control Protocol (IPCP). 1992 May.
RFC1334
:Lloyd, B.; Simpson, W.A. PPP authentication protocols. 1992 October.


;AUTHENTICATION
==NOTES==
The following signals have the specified effect when sent to the ppp process.


The  PAP  and  CHAP secrets files can be setup to restrict
SIGINT, SIGTERM
the set of IP addresses which individual users may use.
:These signals cause ppp to terminate the link (by closing LCP), restore the serial device settings, and exit.


The default behaviour of ppp is to agree  to  authenticate
==BUGS==
if  requested, and to not require authentication from the
Usability issues, several to be resolved prior to GA.
peer.  However, ppp 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
[[Category:Network]]
from    secrets  files,  $ETC/pap.sct  for  PAP,  and
$ETC/chap.sct 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 ppp 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 similar to the options
      file.  A secret is specified by a line containing at least
      3 words, in the order client, server, secret.  Any follow-
      ing 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  (wild-
      card).  When selecting a secret, ppp takes the best match,
      i.e. the match with the fewest wildcards.
 
      A secrets file contains both secrets for use in  authenti-
      cating  other  hosts,  plus  secrets which can be used 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 supplied)
 
      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 host-
          name,
          then use that host name
 
      else the remote name is the null string "".
 
      Secrets are selected from the PAP secrets file as follows:
 
      o For authenticating the peer, look for a secret with
        client ==
        username  specified in the PAP authenticate-request, and
        server == local name.
 
      o  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  password supplied by the peer.  If the pass-
      word 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 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  cer-
      tain  users,  and to restrict the set of IP addresses that
      each user can use.
 
      Secrets are selected from the CHAP secrets  file  as  fol-
      lows:
 
      o  For  authenticating the peer, look for a secret with
        client == name
        specified  in  the  CHAP-Response message, and server ==
        local name.
 
      o  For authenticating ourselves to the peer, look  for  a
        secret with
        client == local name, and server ==  name  specified  in
        the CHAP-Challenge message.
 
      Authentication  must  be  satisfactorily  completed before
      IPCP (or  any  other  Network Control  Protocol)  can  be
      started.  If authentication fails, ppp 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.
 
ROUTING
      When IPCP negotiation is completed successfully, ppp  will
      inform  the  TCP/IP  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 modi-
      fication to routing tables and/or ARP (Address  Resolution
      Protocol) tables.  In some cases this may be done automat-
      ically through the actions of command scripts, 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  ppp  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  exam-
      ple  on  a  server machine connected to a LAN, in order to
      allow other hosts to communicate  with  the  remote  host.
      The  proxyarp  option  causes  ppp  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,
      ppp  creates  a permanent, published ARP entry with the IP
      address of the remote host and the hardware address of the
      network interface found.
 
EXAMPLES
      In  the simplest case, you can connect the serial ports of
      two machines via a NULL modem cable and  issue  a  command
      like
 
              ppp com1 38400 passive
 
      to each machine.
 
      The  process  of logging in to a host machine and starting
      ppp can be automated by using the connect  option  to  run
      slattach or a REXX script, for example:
 
              ppp com1 38400 connect "slattach AT OK ATDT999-9999
              CONNECT login: foobar Password: password"
 
      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).  Don't use an
      rlogin in the path - many implementations are  not  trans-
      parent;  they  will remove the sequence [0xff, 0xff, 0x73,
      0x73, followed by any 8 bytes] from the stream.
 
DIAGNOSTICS
      Messages  are  logged  to  both  the  console  and  the
      $ETC/ppp<n>.log file.
 
FILES
      $ETC/ppp<n>.pid
              Process-ID for ppp process on ppp interface unit n.
 
      $ETC/pap.sct
              Usernames,  passwords  and  IP  addresses  for  PAP
              authentication.
 
      $ETC/chap.sct
              Names,  secrets and IP addresses for CHAP authenti-
              cation.
 
      $ETC/ppp.cfg
              System default options for ppp,  read  before  user
              default options or command-line options.
 
      $HOME/ppprc
              User  default  options,  read  before  command-line
              options.
 
SEE ALSO
      RFC1144
              Jacobson, V.  Compressing TCP/IP headers  for  low-
              speed serial links.  1990 February.
 
      RFC1321
              Rivest, R.  The MD5 Message-Digest Algorithm.  1992
              April.
 
      RFC1331
              Simpson, W.A.  Point-to-Point  Protocol  (PPP)  for
              the  transmission  of multi-protocol datagrams over
              point-to-point links.  1992 May.
 
      RFC1332
              McGregor, G.  PPP Internet Protocol Control  Proto-
              col (IPCP).  1992 May.
 
      RFC1334
              Lloyd, B.; Simpson, W.A.  PPP authentication proto-
              cols.  1992 October.
 
 
;NOTES
The following signals have the specified effect when  sent to the ppp process.
 
      SIGINT, SIGTERM
              These  signals  cause ppp to terminate the link (by
              closing LCP), restore the serial  device  settings,
              and exit.
 
;BUGS
Usability issues, several to be resolved prior to GA.

Latest revision as of 21:06, 12 January 2026

NAME

ppp - Point to Point Protocol for OS/2 TCP/IP 2.0

SYNOPSIS

ppp [ options ] [ com port ] [ speed ]

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 networklayer protocols.

The encapsulation scheme is provided by an OS/2 Ring 3 driver and an interface to the TCP/IP kernel. PPP provides the basic LCP, authentication support, and an NCP for establishing and configuring the Internet Protocol (IP) (called the IP Control Protocol, IPCP).

FREQUENTLY USED OPTIONS

<com port>
Communicate over the named com device. If no device name is given, ppp will use com1.
<speed>
Set the async port line speed to <speed>.
asyncmap <map>
Set the async character map to <map>. This map describes which control characters cannot be successfully received over the serial line. ppp will ask the peer to send these characters as a 2-byte "escape" sequence. The argument is a 32 bit hex number with each bit representing a character to escape. Bit 0 (00000001) represents the character 0x00; bit 31 (80000000) represents the character 0x1f or ^_. The default asyncmap is 0. If multiple asyncmap options are given, the values are ORed together.
auth
Require the peer to authenticate itself before allowing network packets to be sent or received.
connect <command>
Use the executable or shell command specified by <command> to set up the serial line. This script would typically use the "slattach" program or a REXX command file to dial the modem and start a remote ppp session.
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.
file <filename>
Read options from file <filename> (the format is described below).
help (-?)
Display ppp usage information for the most common options.
mru <n>
Set the MRU [Maximum Receive Unit] value to <n> for negotiation. ppp 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 interactive links (40 bytes for TCP/IP header + 256 bytes of data).
netmask <n>
Set the interface netmask to <n>, a 32 bit netmask in "decimal dot" notation (e.g. 255.255.255.0).
passive
Enables the "passive" option in the LCP. With this option, ppp will attempt to initiate a connection; if no reply is received from the peer, ppp will then just wait passively for a valid LCP packet from the peer (instead of exiting, as it does without this option).
restart
Restart LCP negotiation after link termination. This overrides the default behavior of terminating the ppp driver after disconnect.
rtscts
Use hardware flow control (i.e. RTS/CTS) to control the flow of data on the serial port.
silent
With this option, ppp will not transmit LCP packets to initiate a connection until a valid LCP packet is received from the peer.

OTHER OPTIONS

<local_IP_address>:<remote_IP_address>
Set the local and/or remote interface IP addresses. Either one may be omitted. The IP addresses can be specified with a host name or in "decimal dot" notation (e.g. "150.203.23.247"). The default local address is the first IP address of the system. The remote address will be obtained from the peer if not specified in any option. Thus, in simple cases, this option is not required.
-all
Don't request or allow negotiation of any options for LCP and IPCP, use default values.
-ac
Disable Address/Control compression negotiation (use default, i.e. disabled).
-am
Disable asyncmap negotiation (use default, i.e. 0xffffffff).
-as <n>
Same as asyncmap <n>
-d
Increase debugging level.
-ip
Disable IP address negotiation. With this option, the remote IP address must be specified with an option on the command line or in an options file.
-mn
Disable magic number negotiation. With this option, ppp cannot detect a looped-back line.
-mru
Disable MRU [Maximum Receive Unit] negotiation (use default, i.e. 1500).
-p
Same as the passive option.
-pc
Disable protocol field compression negotiation (use default, i.e. disabled).
+ua <p>
Agree to authenticate using PAP [Password Authentication Protocol] if requested by the peer, and use the data in file

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.

+pap
Require the peer to authenticate itself using PAP.
-pap
Don't agree to authenticate using PAP.
+chap
Require the peer to authenticate itself using CHAP [Cryptographic Handshake Authentication Protocol] authentication.
-chap
Don't agree to authenticate using CHAP.
-vj
Disable negotiation of Van Jacobson style IP header compression (use default, i.e. no compression).
debug
Increase debugging level (same as -d ).
domain <d>
Append the domain name <d> to the local host name for authentication purposes. For example, if gethostname() returns the name foobar, but the fully qualified domain name is foobar.IBM.COM, you would use the domain option to set the domain name to IBM.COM.
exit
Causes the ppp driver to terminate on detecting loss of the modem Data Carrier Detect (DCD) signal.
idle <n>
Set the amount of inactivity time (no IP traffic) until the ppp driver hangs up the connection.
local
Don't use modem control lines.
name <n>
Set the name of the local system for authentication purposes to <n>.
user <u>
Set the user name to use for authenticating this machine with the peer using PAP to
<u>
.
usehostname
Enforce the use of the hostname as the name of the local system for authentication purposes (overrides the name option).
remotename <n>
Set the assumed name of the remote system for authentication purposes to <n>.
proxyarp
Add an entry to this system's ARP [Address Resolution Protocol] table with the IP address of the peer and the Token-Ring/Ethernet address of this system.
login
Use the system password database for authenticating the peer using PAP.
secret <secret>
Use the secret <secret> for PAP and CHAP authentication with the peer.
lcp-restart <n>
Set the LCP restart interval (retransmission timeout) to <n> seconds (default 3).
lcp-max-terminate <n>
Set the maximum number of LCP terminate-request transmissions to <n> (default 3).
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).
ipcp-restart <n>
Set the IPCP restart interval (retransmission timeout) to <n> seconds (default 5 seconds).
ipcp-max-terminate <n>
Set the maximum number of IPCP terminate-request transmissions to <n> (default 3).
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).
pap-restart <n>
Set the PAP restart interval (retransmission timeout) to <n> seconds (default 5 seconds).
pap-max-authreq <n>
Set the maximum number of PAP authenticate-request transmissions to <n> (default 10).
chap-restart <n>
Set the CHAP restart interval (retransmission timeout for challenges) to <n> seconds (default 5 seconds).
chap-max-challenge <n>
Set the maximum number of CHAP challenge transmissions to <n> (default 10).
chap-interval <n>
If this option is given, ppp will rechallenge the peer every <n> seconds.

OPTIONS FILES

Options can be taken from files as well as the command line. ppp reads options from the files $ETC/ppp.cfg and $HOME/ppprc before looking at the command line. 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 quotes ("). A backslash (\) quotes the following character. A hash (#) starts a comment, which continues until the end of the line.

AUTHENTICATION

The PAP and CHAP secrets files can be setup to restrict the set of IP addresses which individual users may use.

The default behaviour of ppp is to agree to authenticate if requested, and to not require authentication from the peer. However, ppp 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/pap.sct for PAP, and $ETC/chap.sct 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 ppp 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 similar to the options file. A secret is specified by a line containing at least 3 words, in the order client, server, 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 (wildcard). When selecting a secret, ppp takes the best match, i.e. the match with the fewest wildcards.

A secrets file contains both secrets for use in authenticating other hosts, plus secrets which can be used 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 supplied)
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 == username 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 password 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 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.

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-Challenge message.

Authentication must be satisfactorily completed before IPCP (or any other Network Control Protocol) can be started. If authentication fails, ppp 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.

ROUTING

When IPCP negotiation is completed successfully, ppp will inform the TCP/IP 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 some cases this may be done automatically through the actions of command scripts, 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 ppp 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 ppp 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, ppp creates a permanent, published ARP entry with the IP address of the remote host and the hardware address of the network interface found.

EXAMPLES

In the simplest case, you can connect the serial ports of two machines via a NULL modem cable and issue a command like

ppp com1 38400 passive

to each machine.

The process of logging in to a host machine and starting ppp can be automated by using the connect option to run slattach or a REXX script, for example:

ppp com1 38400 connect "slattach AT OK ATDT999-9999
CONNECT login: foobar Password: password"

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). Don't use an rlogin in the path - many implementations are not transparent; they will remove the sequence [0xff, 0xff, 0x73, 0x73, followed by any 8 bytes] from the stream.

DIAGNOSTICS

Messages are logged to both the console and the $ETC/ppp<n>.log file.

FILES

$ETC/ppp<n>.pid
Process-ID for ppp process on ppp interface unit n.
$ETC/pap.sct
Usernames, passwords and IP addresses for PAP authentication.
$ETC/chap.sct
Names, secrets and IP addresses for CHAP authentication.
$ETC/ppp.cfg
System default options for ppp, read before user default options or command-line options.
$HOME/ppprc
User default options, read before command-line options.

SEE ALSO

RFC1144

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

RFC1321

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

RFC1331

Simpson, W.A. Point-to-Point Protocol (PPP) for the transmission of multi-protocol datagrams over point-to-point links. 1992 May.

RFC1332

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

RFC1334

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

NOTES

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

SIGINT, SIGTERM

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

BUGS

Usability issues, several to be resolved prior to GA.