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

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

 * Communicate over  the  named  com  device. If no device name is given, ppp will use com1.
 * Communicate over  the  named  com  device. If no device name is given, ppp will use com1.


 * Set the async port line speed to.
 * Set the async port line speed to.


 * asyncmap
 * Set the async character map to  .   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.

Use the  executable  or shell command specified by              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.
 * connect

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.
 * defaultroute

Read options from file (the  format  is              described below).
 * file

Display ppp  usage information for the most common options.
 * help (-?)

Set the MRU [Maximum Receive Unit] value to  for negotiation. ppp will ask the peer to send packets of no more than  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).
 * mru 

Set the interface netmask to , a 32 bit netmask in "decimal dot" notation (e.g. 255.255.255.0).
 * netmask 

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).
 * passive

Restart LCP  negotiation  after  link termination. This overrides the default behavior of terminating the ppp driver after disconnect.
 * restart


 * 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
: 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  Same as asyncmap 

-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 

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 ).

Append the domain name  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.
 * domain 

exit  Causes  the  ppp  driver  to terminate on detecting loss of the modem Data Carrier Detect (DCD) signal.

idle  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>.

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

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

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 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 the peer using PAP.

secret Use the secret for PAP and CHAP authenti- cation with the peer.

lcp-restart <n> Set the LCP restart interval (retransmission time-              out) 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 time-             out) 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 time-              out) 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 time-             out  for challenges) to <n> seconds (default 5 sec-              onds).

chap-max-challenge <n> Set the maximum number of CHAP challenge transmis- sions 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 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:


 * 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 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:


 * 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.

BUGS
Usability issues, several to be resolved prior to GA.