C#实现的DHCP服务器

Network Working Group S. Alexander Request for Comments: 2132 Silicon Graphics, Inc. Obsoletes: 1533 R. Droms Category: Standards Track Bucknell University March 1997 DHCP Options and BOOTP Vendor Extensions Status of this memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract The Dynamic Host Configuration Protocol (DHCP) [1] provides a framework for passing configuration information to hosts on a TCP/IP network. Configuration parameters and other control information are carried in tagged data items that are stored in the 'options' field of the DHCP message. The data items themselves are also called "options." This document specifies the current set of DHCP options. Future options will be specified in separate RFCs. The current list of valid options is also available in ftp://ftp.isi.edu/in- notes/iana/assignments [22]. All of the vendor information extensions defined in RFC 1497 [2] may be used as DHCP options. The definitions given in RFC 1497 are included in this document, which supersedes RFC 1497. All of the DHCP options defined in this document, except for those specific to DHCP as defined in section 9, may be used as BOOTP vendor information extensions. Table of Contents 1. Introduction .............................................. 2 2. BOOTP Extension/DHCP Option Field Format .................. 4 3. RFC 1497 Vendor Extensions ................................ 5 4. IP Layer Parameters per Host .............................. 11 5. IP Layer Parameters per Interface ........................ 13 6. Link Layer Parameters per Interface ....................... 16 7. TCP Parameters ............................................ 17 8. Application and Service Parameters ........................ 18 9. DHCP Extensions ........................................... 25 Alexander & Droms Standards Track [Page 1]  RFC 2132 DHCP Options and BOOTP Vendor Extensions March 1997 10. Defining new extensions ................................... 31 11. Acknowledgements .......................................... 31 12. References ................................................ 32 13. Security Considerations ................................... 33 14. Authors' Addresses ........................................ 34 1. Introduction This document specifies options for use with both the Dynamic Host Configuration Protocol and the Bootstrap Protocol. The full description of DHCP packet formats may be found in the DHCP specification document [1], and the full description of BOOTP packet formats may be found in the BOOTP specification document [3]. This document defines the format of information in the last field of DHCP packets ('options') and of BOOTP packets ('vend'). The remainder of this section defines a generalized use of this area for giving information useful to a wide class of machines, operating systems and configurations. Sites with a single DHCP or BOOTP server that is shared among heterogeneous clients may choose to define other, site- specific formats for the use of the 'options' field. Section 2 of this memo describes the formats of DHCP options and BOOTP vendor extensions. Section 3 describes options defined in previous documents for use with BOOTP (all may also be used with DHCP). Sections 4-8 define new options intended for use with both DHCP and BOOTP. Section 9 defines options used only in DHCP. References further describing most of the options defined in sections 2-6 can be found in section 12. The use of the options defined in section 9 is described in the DHCP specification [1]. Information on registering new options is contained in section 10. This document updates the definition of DHCP/BOOTP options that appears in RFC1533. The classing mechanism has been extended to include vendor classes as described in section 8.4 and 9.13. The new procedure for defining new DHCP/BOOTP options in described in section 10. Several new options, including NIS+ domain and servers, Mobile IP home agent, SMTP server, TFTP server and Bootfile server, have been added. Text giving definitions used throughout the document has been added in section 1.1. Text emphasizing the need for uniqueness of client-identifiers has been added to section 9.14. Alexander & Droms Standards Track [Page 2]  RFC 2132 DHCP Options and BOOTP Vendor Extensions March 1997 1.1 Requirements Throughout this document, the words that are used to define the significance of particular requirements are capitalized. These words are: o "MUST" This word or the adjective "REQUIRED" means that the item is an absolute requirement of this specification. o "MUST NOT" This phrase means that the item is an absolute prohibition of this specification. o "SHOULD" This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course. o "SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances when the listed behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label. o "MAY" This word or the adjective "OPTIONAL" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item. 1.2 Terminology This document uses the following terms: o "DHCP client" A DHCP client or "client" is an Internet host using DHCP to obtain configuration parameters such as a network address. Alexander & Droms Standards Track [Page 3]  RFC 2132 DHCP Options and BOOTP Vendor Extensions March 1997 o "DHCP server" A DHCP server of "server"is an Internet host that returns configuration parameters to DHCP clients. o "binding" A binding is a collection of configuration parameters, including at least an IP address, associated with or "bound to" a DHCP client. Bindings are managed by DHCP servers. 2. BOOTP Extension/DHCP Option Field Format DHCP options have the same format as the BOOTP 'vendor extensions' defined in RFC 1497 [2]. Options may be fixed length or variable length. All options begin with a tag octet, which uniquely identifies the option. Fixed-length options without data consist of only a tag octet. Only options 0 and 255 are fixed length. All other options are variable-length with a length octet following the tag octet. The value of the length octet does not include the two octets specifying the tag and l