rfc2132.txt

DHCP服务器源码

   The code for the log server option is 7.  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
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  7  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--



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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


3.10. Cookie Server Option

   The cookie server option specifies a list of RFC 865 [9] cookie
   servers available to the client.  Servers SHOULD be listed in order
   of preference.

   The code for the log server option is 8.  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
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  8  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

3.11. LPR Server Option

   The LPR server option specifies a list of RFC 1179 [10] line printer
   servers available to the client.  Servers SHOULD be listed in order
   of preference.

   The code for the LPR server option is 9.  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
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  9  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

3.12. Impress Server Option

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

   The code for the Impress server option is 10.  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
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  10 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

3.13. Resource Location Server Option

   This option specifies a list of RFC 887 [11] Resource Location
   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 this option is 11.  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
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  11 |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

3.14. Host Name Option

   This option specifies the name of the client.  The name may or may
   not be qualified with the local domain name (see section 3.17 for the
   preferred way to retrieve the domain name).  See RFC 1035 for
   character set restrictions.

   The code for this option is 12, and its minimum length is 1.

    Code   Len                 Host Name
   +-----+-----+-----+-----+-----+-----+-----+-----+--
   |  12 |  n  |  h1 |  h2 |  h3 |  h4 |  h5 |  h6 |  ...
   +-----+-----+-----+-----+-----+-----+-----+-----+--

3.15. Boot File Size Option

   This option specifies the length in 512-octet blocks of the default
   boot image for the client.  The file length is specified as an
   unsigned 16-bit integer.

   The code for this option is 13, and its length is 2.

    Code   Len   File Size
   +-----+-----+-----+-----+
   |  13 |  2  |  l1 |  l2 |
   +-----+-----+-----+-----+

3.16. Merit Dump File

   This option specifies the path-name of a file to which the client's
   core image should be dumped in the event the client crashes.  The
   path is formatted as a character string consisting of characters from
   the NVT ASCII character set.

   The code for this option is 14.  Its minimum length is 1.

    Code   Len      Dump File Pathname
   +-----+-----+-----+-----+-----+-----+---
   |  14 |  n  |  n1 |  n2 |  n3 |  n4 | ...
   +-----+-----+-----+-----+-----+-----+---



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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


3.17. Domain Name

   This option specifies the domain name that client should use when
   resolving hostnames via the Domain Name System.

   The code for this option is 15.  Its minimum length is 1.

    Code   Len        Domain Name
   +-----+-----+-----+-----+-----+-----+--
   |  15 |  n  |  d1 |  d2 |  d3 |  d4 |  ...
   +-----+-----+-----+-----+-----+-----+--

3.18. Swap Server

   This specifies the IP address of the client's swap server.

   The code for this option is 16 and its length is 4.

    Code   Len    Swap Server Address
   +-----+-----+-----+-----+-----+-----+
   |  16 |  n  |  a1 |  a2 |  a3 |  a4 |
   +-----+-----+-----+-----+-----+-----+

3.19. Root Path

   This option specifies the path-name that contains the client's root
   disk.  The path is formatted as a character string consisting of
   characters from the NVT ASCII character set.

   The code for this option is 17.  Its minimum length is 1.

    Code   Len      Root Disk Pathname
   +-----+-----+-----+-----+-----+-----+---
   |  17 |  n  |  n1 |  n2 |  n3 |  n4 | ...
   +-----+-----+-----+-----+-----+-----+---

3.20. Extensions Path

   A string to specify a file, retrievable via TFTP, which contains
   information which can be interpreted in the same way as the 64-octet
   vendor-extension field within the BOOTP response, with the following
   exceptions:

          - the length of the file is unconstrained;
          - all references to Tag 18 (i.e., instances of the
            BOOTP Extensions Path field) within the file are
            ignored.




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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   The code for this option is 18.  Its minimum length is 1.

    Code   Len      Extensions Pathname
   +-----+-----+-----+-----+-----+-----+---
   |  18 |  n  |  n1 |  n2 |  n3 |  n4 | ...
   +-----+-----+-----+-----+-----+-----+---

4. IP Layer Parameters per Host

   This section details the options that affect the operation of the IP
   layer on a per-host basis.

4.1. IP Forwarding Enable/Disable Option

   This option specifies whether the client should configure its IP
   layer for packet forwarding.  A value of 0 means disable IP
   forwarding, and a value of 1 means enable IP forwarding.

   The code for this option is 19, and its length is 1.

    Code   Len  Value
   +-----+-----+-----+
   |  19 |  1  | 0/1 |
   +-----+-----+-----+

4.2. Non-Local Source Routing Enable/Disable Option

   This option specifies whether the client should configure its IP
   layer to allow forwarding of datagrams with non-local source routes
   (see Section 3.3.5 of [4] for a discussion of this topic).  A value
   of 0 means disallow forwarding of such datagrams, and a value of 1
   means allow forwarding.

   The code for this option is 20, and its length is 1.

    Code   Len  Value
   +-----+-----+-----+
   |  20 |  1  | 0/1 |
   +-----+-----+-----+

4.3. Policy Filter Option

   This option specifies policy filters for non-local source routing.
   The filters consist of a list of IP addresses and masks which specify
   destination/mask pairs with which to filter incoming source routes.

   Any source routed datagram whose next-hop address does not match one
   of the filters should be discarded by the client.



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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   See [4] for further information.

   The code for this option is 21.  The minimum length of this option is
   8, and the length MUST be a multiple of 8.

    Code   Len         Address 1                  Mask 1
   +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
   |  21 |  n  |  a1 |  a2 |  a3 |  a4 |  m1 |  m2 |  m3 |  m4 |
   +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
           Address 2                  Mask 2
   +-----+-----+-----+-----+-----+-----+-----+-----+---
   |  a1 |  a2 |  a3 |  a4 |  m1 |  m2 |  m3 |  m4 | ...
   +-----+-----+-----+-----+-----+-----+-----+-----+---

4.4. Maximum Datagram Reassembly Size

   This option specifies the maximum size datagram that the client
   should be prepared to reassemble.  The size is specified as a 16-bit
   unsigned integer.  The minimum value legal value is 576.

   The code for this option is 22, and its length is 2.

    Code   Len      Size
   +-----+-----+-----+-----+
   |  22 |  2  |  s1 |  s2 |
   +-----+-----+-----+-----+

4.5. Default IP Time-to-live

   This option specifies the default time-to-live that the client should
   use on outgoing datagrams.  The TTL is specified as an octet with a
   value between 1 and 255.

   The code for this option is 23, and its length is 1.

    Code   Len   TTL
   +-----+-----+-----+
   |  23 |  1  | ttl |
   +-----+-----+-----+

4.6. Path MTU Aging Timeout Option

   This option specifies the timeout (in seconds) to use when aging Path
   MTU values discovered by the mechanism defined in RFC 1191 [12].  The
   timeout is specified as a 32-bit unsigned integer.

   The code for this option is 24, and its length is 4.




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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


    Code   Len           Timeout
   +-----+-----+-----+-----+-----+-----+
   |  24 |  4  |  t1 |  t2 |  t3 |  t4 |
   +-----+-----+-----+-----+-----+-----+

4.7. Path MTU Plateau Table Option

   This option specifies a table of MTU sizes to use when performing
   Path MTU Discovery as defined in RFC 1191.  The table is formatted as
   a list of 16-bit unsigned integers, ordered from smallest to largest.
   The minimum MTU value cannot be smaller than 68.

   The code for this option is 25.  Its minimum length is 2, and the
   length MUST be a multiple of 2.

    Code   Len     Size 1      Size 2
   +-----+-----+-----+-----+-----+-----+---
   |  25 |  n  |  s1 |  s2 |  s1 |  s2 | ...
   +-----+-----+-----+-----+-----+-----+---

5. IP Layer Parameters per Interface

   This section details the options that affect the operation of the IP
   layer on a per-interface basis.  It is expected that a client can
   issue multiple requests, one per interface, in order to configure
   interfaces with their specific parameters.

5.1. Interface MTU Option

   This option specifies the MTU to use on this interface.  The MTU is
   specified as a 16-bit unsigned integer.  The minimum legal value for
   the MTU is 68.

   The code for this option is 26, and its length is 2.

    Code   Len      MTU
   +-----+-----+-----+-----+
   |  26 |  2  |  m1 |  m2 |
   +-----+-----+-----+-----+

5.2. All Subnets are Local Option

   This option specifies whether or not the client may assume that all
   subnets of the IP network to which the client is connected use the
   same MTU as the subnet of that network to which the client is
   directly connected.  A value of 1 indicates that all subnets share
   the same MTU.  A value of 0 means that the client should assume that
   some subnets of the directly connected network may have smaller MTUs.



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RFC 2132        DHCP Options and BOOTP Vendor Extensions      March 1997


   The code for this option is 27, and its length is 1.

    Code   Len  Value
   +-----+-----+-----+
   |  27 |  1  | 0/1 |
   +-----+-----+-----+

5.3. Broadcast Address Option

   This option specifies the broadcast address in use on the client's
   subnet.  Legal values for broadcast addresses are specified in
   section 3.2.1.3 of [4].

   The code for this option is 28, and its length is 4.

    Code   Len     Broadcast Address
   +-----+-----+-----+-----+-----+-----+
   |  28 |  4  |  b1 |  b2 |  b3 |  b4 |
   +-----+-----+-----+-----+-----+-----+

5.4. Perform Mask Discovery Option

   This option specifies whether or not the client should perform subnet
   mask discovery using ICMP.  A value of 0 indicates that the client
   should not perform mask discovery.  A value of 1 means that the
   client should perform mask discovery.

   The code for this option is 29, and its length is 1.

    Code   Len  Value