rfc2132.txt

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    Code   Len       NetBIOS Scope
   +-----+-----+-----+-----+-----+-----+----
   |  47 |  n  |  s1 |  s2 |  s3 |  s4 | ...
   +-----+-----+-----+-----+-----+-----+----

8.9. X Window System Font Server Option

   This option specifies a list of X Window System [21] Font servers
   available to the client. Servers SHOULD be listed in order of
   preference.

   The code for this option is 48.  The minimum length of this option is
   4 octets, and the length MUST be a multiple of 4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+---
   |  48 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |   ...
   +-----+-----+-----+-----+-----+-----+-----+-----+---

8.10. X Window System Display Manager Option

   This option specifies a list of IP addresses of systems that are
   running the X Window System Display Manager and are available to the
   client.

   Addresses SHOULD be listed in order of preference.





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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   The code for the this option is 49. The minimum length of this option
   is 4, and the length MUST be a multiple of 4.

    Code   Len         Address 1               Address 2

   +-----+-----+-----+-----+-----+-----+-----+-----+---
   |  49 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |   ...
   +-----+-----+-----+-----+-----+-----+-----+-----+---

8.11. Network Information Service+ Domain Option

   This option specifies the name of the client's NIS+ [17] domain.  The
   domain is formatted as a character string consisting of characters
   from the NVT ASCII character set.

   The code for this option is 64.  Its minimum length is 1.

    Code   Len      NIS Client Domain Name
   +-----+-----+-----+-----+-----+-----+---
   |  64 |  n  |  n1 |  n2 |  n3 |  n4 | ...
   +-----+-----+-----+-----+-----+-----+---

8.12. Network Information Service+ Servers Option

   This option specifies a list of IP addresses indicating NIS+ servers
   available to the client.  Servers SHOULD be listed in order of
   preference.

   The code for this option is 65.  Its minimum length is 4, and the
   length MUST be a multiple of 4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  65 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.13. Mobile IP Home Agent option

   This option specifies a list of IP addresses indicating mobile IP
   home agents available to the client.  Agents SHOULD be listed in
   order of preference.

   The code for this option is 68.  Its minimum length is 0 (indicating
   no home agents are available) and the length MUST be a multiple of 4.
   It is expected that the usual length will be four octets, containing
   a single home agent's address.





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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


    Code Len    Home Agent Addresses (zero or more)
   +-----+-----+-----+-----+-----+-----+--
   | 68  |  n  | a1  | a2  | a3  | a4  | ...
   +-----+-----+-----+-----+-----+-----+--

8.14. Simple Mail Transport Protocol (SMTP) Server Option

   The SMTP server option specifies a list of SMTP servers available to
   the client.  Servers SHOULD be listed in order of preference.

   The code for the SMTP server option is 69.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 69  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.15. Post Office Protocol (POP3) Server Option

   The POP3 server option specifies a list of POP3 available to the
   client.  Servers SHOULD be listed in order of preference.

   The code for the POP3 server option is 70.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 70  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.16. Network News Transport Protocol (NNTP) Server Option

   The NNTP server option specifies a list of NNTP available to the
   client.  Servers SHOULD be listed in order of preference.

   The code for the NNTP server option is 71. The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 71  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--





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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


8.17. Default World Wide Web (WWW) Server Option

   The WWW server option specifies a list of WWW available to the
   client.  Servers SHOULD be listed in order of preference.

   The code for the WWW server option is 72.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 72  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.18. Default Finger Server Option

   The Finger server option specifies a list of Finger available to the
   client.  Servers SHOULD be listed in order of preference.

   The code for the Finger server option is 73.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 73  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.19. Default Internet Relay Chat (IRC) Server Option

   The IRC server option specifies a list of IRC available to the
   client.  Servers SHOULD be listed in order of preference.

   The code for the IRC server option is 74.  The minimum length for
   this option is 4 octets, and the length MUST always be a multiple of
   4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 74  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.20. StreetTalk Server Option

   The StreetTalk server option specifies a list of StreetTalk servers
   available to the client.  Servers SHOULD be listed in order of
   preference.




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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   The code for the StreetTalk server option is 75.  The minimum length
   for this option is 4 octets, and the length MUST always be a multiple
   of 4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 75  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

8.21. StreetTalk Directory Assistance (STDA) Server Option

   The StreetTalk Directory Assistance (STDA) server option specifies a
   list of STDA servers available to the client.  Servers SHOULD be
   listed in order of preference.

   The code for the StreetTalk Directory Assistance server option is 76.
   The minimum length for this option is 4 octets, and the length MUST
   always be a multiple of 4.

    Code   Len         Address 1               Address 2
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   | 76  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

9. DHCP Extensions

   This section details the options that are specific to DHCP.

9.1. Requested IP Address

   This option is used in a client request (DHCPDISCOVER) to allow the
   client to request that a particular IP address be assigned.

   The code for this option is 50, and its length is 4.

    Code   Len          Address
   +-----+-----+-----+-----+-----+-----+
   |  50 |  4  |  a1 |  a2 |  a3 |  a4 |
   +-----+-----+-----+-----+-----+-----+

9.2. IP Address Lease Time

   This option is used in a client request (DHCPDISCOVER or DHCPREQUEST)
   to allow the client to request a lease time for the IP address.  In a
   server reply (DHCPOFFER), a DHCP server uses this option to specify
   the lease time it is willing to offer.





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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   The time is in units of seconds, and is specified as a 32-bit
   unsigned integer.

   The code for this option is 51, and its length is 4.

    Code   Len         Lease Time
   +-----+-----+-----+-----+-----+-----+
   |  51 |  4  |  t1 |  t2 |  t3 |  t4 |
   +-----+-----+-----+-----+-----+-----+

9.3. Option Overload

   This option is used to indicate that the DHCP 'sname' or 'file'
   fields are being overloaded by using them to carry DHCP options. A
   DHCP server inserts this option if the returned parameters will
   exceed the usual space allotted for options.

   If this option is present, the client interprets the specified
   additional fields after it concludes interpretation of the standard
   option fields.

   The code for this option is 52, and its length is 1.  Legal values
   for this option are:

           Value   Meaning
           -----   --------
             1     the 'file' field is used to hold options
             2     the 'sname' field is used to hold options
             3     both fields are used to hold options

    Code   Len  Value
   +-----+-----+-----+
   |  52 |  1  |1/2/3|
   +-----+-----+-----+

9.4 TFTP server name

   This option is used to identify a TFTP server when the 'sname' field
   in the DHCP header has been used for DHCP options.

   The code for this option is 66, and its minimum length is 1.

       Code  Len   TFTP server
      +-----+-----+-----+-----+-----+---
      | 66  |  n  |  c1 |  c2 |  c3 | ...
      +-----+-----+-----+-----+-----+---





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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


9.5 Bootfile name

   This option is used to identify a bootfile when the 'file' field in
   the DHCP header has been used for DHCP options.

   The code for this option is 67, and its minimum length is 1.

       Code  Len   Bootfile name
      +-----+-----+-----+-----+-----+---
      | 67  |  n  |  c1 |  c2 |  c3 | ...
      +-----+-----+-----+-----+-----+---

9.6. DHCP Message Type

   This option is used to convey the type of the DHCP message.  The code
   for this option is 53, and its length is 1.  Legal values for this
   option are:

           Value   Message Type
           -----   ------------
             1     DHCPDISCOVER
             2     DHCPOFFER
             3     DHCPREQUEST
             4     DHCPDECLINE
             5     DHCPACK
             6     DHCPNAK
             7     DHCPRELEASE
             8     DHCPINFORM

    Code   Len  Type
   +-----+-----+-----+
   |  53 |  1  | 1-9 |
   +-----+-----+-----+

9.7. Server Identifier

   This option is used in DHCPOFFER and DHCPREQUEST messages, and may
   optionally be included in the DHCPACK and DHCPNAK messages.  DHCP
   servers include this option in the DHCPOFFER in order to allow the
   client to distinguish between lease offers.  DHCP clients use the
   contents of the 'server identifier' field as the destination address
   for any DHCP messages unicast to the DHCP server.  DHCP clients also
   indicate which of several lease offers is being accepted by including
   this option in a DHCPREQUEST message.

   The identifier is the IP address of the selected server.

   The code for this option is 54, and its length is 4.



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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


    Code   Len            Address
   +-----+-----+-----+-----+-----+-----+
   |  54 |  4  |  a1 |  a2 |  a3 |  a4 |
   +-----+-----+-----+-----+-----+-----+

9.8. Parameter Request List

   This option is used by a DHCP client to request values for specified
   configuration parameters.  The list of requested parameters is
   specified as n octets, where each octet is a valid DHCP option code