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dhcptags(4)							  dhcptags(4)


  dhcptags - DHCP and BOOTP server database


  Parameters (or options) returned to the client by the	DHCP/BOOTP protocol
  are encoded in the so-called vendor field of the BOOTP packet.  Each option
  is identified	numerically, and also carries a	length specifier.  The
  dhcptags file	identifies the type of each option, labels each	with a short
  mnemonic text	string for use in the dhcpcap database,	and provides a
  description of each for use in the xjoin program.

  Options defined by DHCP are of three general types:

      The semantics of which all client	and server DHCP	implementations	agree
      upon.  These are administered by the Internet Assigned Numbers Author-
      ity (IANA).  These options are numbered from 1 to	127 and	255.

      Within a specific	site all client	and server implementations agree as
      to the semantics,	but at another site the	type and meaning of an option
      may be quite different.  These options are numbered from 128 to 254.

      Each vendor may define 256 options unique	to that	vendor.	 The vendor
      is identified within a DHCP packet by the	"Vendor	Class" option (#60).
      An option	with a specific	numeric	identifier belonging to	one vendor
      will, in general,	have a type and	semantics different from those of
      another vendor.  Vendor options are "super-encapsulated" into the	ven-
      dor field	(#43): within a	specific DHCP packet there may be several
      instances	of option #43.

  As well as these, the	DHCP implementation defines certain "pseudo" options,
  numbered from	512 upward.  These are used by the server to identify items
  in its database which	either correspond to fixed fields in the BOOTP packet
  (such	as the "siaddr"	field) or which	though not options themselves are
  used in constructing valid options. For example, the "home directory"	used
  in constructing the exact path to a boot image.

  In general, the joind	server knows little about the semantics	of any of the
  first	three types of options.	 Its only duty is to deliver those values to
  clients that need them.  The responsibility for understanding	and using the
  data rests with the client.  Pseudo-tags, on the contrary, have a meaning
  specific to joind, and consequently are not added to this list.  The only
  useful edit that can be performed on the pseudo-tags is to change the
  description or the mnemonic.


  Blank	lines and those	whose first nonwhitespace character is '#' are
  ignored.  Data entries are written one per line and have seven fields. An
  individual entry cannot be continued onto another line.

  The fields are (in order):

    +  The tag number

    +  Identifier as used in bootptab file

    +  Grouping	in GUI

    +  Vendor class

    +  Data type.  Choose from the following (case insensitive)	list:



	   A 1-byte value

	   A 2-byte value

	   A 4-byte value

	   A printable character string

       ip  An IP address

	   A list of IP	addresses

	   A list of 2-byte values

	   A array of 1-byte values

	   Either true or false

    +  Column grouping in GUI

    +  Long name

  Tag List

  The currently	recognized /etc/join/dhcptags tags are:

  as  Maximum reassembly size

  at  Arp timeout

  ba  Broadcast	address	of network

  bf  Boot file

  br  Be a router

  bs  Boot file	size (512 octet	blocks)

  bw  Netbios name servers

  bx  Netbios datagram distribution servers

  by  Netbios node type

  bz  Netbios scope

  cb  Path to join client binary

  cs  Cookie servers

  ct  Class type

  df  Dump file

  dn  DNS domain name

  ds  Domain name servers

  ef  Encapsulate flavor

  ep  Path of the extensions file

  fn  Forward nonlocal datagrams

  gw  Gateways (IP rosters)

  ha  Hardware address

  hd  Home directory

  hn  Send host	name

  ho  Host name

  ht  Hardware type

  id  Client id

  im  Impress servers

  ip  Host or network IP address

  it  IP TTL

  ki  Keep alive interval

  ko  Keep alive octet

  lg  Log servers

  lp  LPR servers

  lt  Lease time

  md  Perform mask discovery

  mf  Publicly mountable file systems

  ms  Supply masks

  ns  IEN-116 name servers

  nt  NTP (network time	protocol) servers

  pf  Policy filters

  pl  PMTU plateaus

  pr  Printcap setup

  ps  SVR4 printer setup

  pt  PMTU timeout

  ra  Reply address override

  rd  Do route discovery

  rl  Resource location	protocol servers

  rp  Root path

  rs  Solicit routes

  sa  TFTP server address (used	by clients)

  si  Boot server address

  sl  Subnets are local

  sm  Subnet mask (host)

  sr  Static routes

  ss  Name service switch

  sw  Swap server address

  t1  DHCP T1

  t2  DHCP T2

  tc  Template host (points to similar host entry)

  td  TFTP root	directory (used	by secure TFTP server)

  to  Time offset (seconds)

  tr  Trailers

  ts  Time servers

  tt  TCP TTL

  tu  MTU

  vm  Vendor magic cookie selector

  wd  Netware domain name

  wo  Netware options

  xd  X	display	managers

  xf  X	font servers

  yd  NIS domain

  ys  NIS map servers

  zd  NIS+ domain

  zs  NIS+ map servers

  There	is also	a generic tag, Tn, where n is an RFC 1533 vendor field tag
  number.  Thus	it is possible to immediately take advantage of	future exten-
  sions	to RFC 1533 without being required to modify the DHCP server (joind).
  Generic data may be represented as either a stream of	hexadecimal numbers
  or as	a quoted string	of ASCII characters.  The length of the	generic	data
  is automatically determined and inserted into	the proper field(s) of the
  RFC 1533-style BOOTP and DHCP	reply.


	    DHCP server	database


  Commands: dhcpparm(8), joind(8).

  Files: bootptab(4),

  DARPA	Internet Request For Comments RFC 1533,	RFC 1541, Assigned Numbers