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NAME    [Toc]    [Back]

       dhcptags - DHCP and BOOTP server database

DESCRIPTION    [Toc]    [Back]

       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 Authority (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 vendor 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.

FORMAT    [Toc]    [Back]

       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 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    [Toc]    [Back]
       The currently recognized /etc/join/dhcptags tags are: Maximum
 reassembly size Arp timeout Broadcast address of network
 Boot file Be a  router  Boot  file  size  (512  octet
       blocks) Netbios name servers Netbios datagram distribution
       servers Netbios node  type  Netbios  scope  Path  to  join
       client  binary  Cookie  servers  Class  type Dump file DNS
       domain name Domain name servers Encapsulate flavor Path of
       the  extensions  file  Forward nonlocal datagrams Gateways
       (IP rosters) Hardware address  Home  directory  Send  host
       name  Host  name  Hardware  type Client id Impress servers
       Host or network IP address IP TTL Keep alive interval Keep
       alive  octet  Log  servers  LPR servers Lease time Perform
       mask discovery  Publicly  mountable  file  systems  Supply
       masks  IEN-116  name  servers  NTP (network time protocol)
       servers Policy filters PMTU plateaus Printcap  setup  SVR4
       printer setup PMTU timeout Reply address override Do route
       discovery Resource location  protocol  servers  Root  path
       Solicit  routes TFTP server address (used by clients) Boot
       server address Subnets are local Subnet mask (host) Static
       routes  Name  service  switch  Swap server address DHCP T1
       DHCP T2 Template host (points to similar host entry)  TFTP
       root  directory  (used  by secure TFTP server) Time offset
       (seconds) Trailers Time servers TCP TTL MTU  Vendor  magic
       cookie selector Netware domain name Netware options X display
 managers X font servers NIS domain  NIS  map  servers
       NIS+ domain 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  extensions 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.

FILES    [Toc]    [Back]

       DHCP server database


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

       Files: bootptab(4),

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

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