draft-ietf-dhc-slp-00.txt   draft-ietf-dhc-slp-01.txt 
Internet Engineering Task Force C. Perkins Internet Engineering Task Force C. Perkins
INTERNET DRAFT IBM INTERNET DRAFT IBM
27 August 1996 14 March 1997
DHCP Options for Service Location Protocol DHCP Options for Service Location Protocol
draft-ietf-dhc-slp-00.txt draft-ietf-dhc-slp-01.txt
Status of This Memo Status of This Memo
This document is a submission to the Dynamic Host Configuration This document is a submission to the Dynamic Host Configuration
Working Group of the Internet Engineering Task Force (IETF). Comments Working Group of the Internet Engineering Task Force (IETF). Comments
should be submitted to the dhcp@bucknell.edu mailing list. should be submitted to the dhcp@bucknell.edu mailing list.
Distribution of this memo is unlimited. Distribution of this memo is unlimited.
This document is an Internet-Draft. Internet-Drafts are working This document is an Internet-Draft. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at and may be updated, replaced, or obsoleted by other documents at
any time. It is inappropriate to use Internet- Drafts as reference any time. It is inappropriate to use Internet- Drafts as reference
material or to cite them other than as ``work in progress.'' material or to cite them other than as ``work in progress.''
To learn the current status of any Internet-Draft, please check the To learn the current status of any Internet-Draft, please check
``1id-abstracts.txt'' listing contained in the Internet- Drafts the ``1id-abstracts.txt'' listing contained in the Internet-Drafts
Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe), Shadow Directories on ftp.is.co.za (Africa), nic.nordu.net (North
munnari.oz.au (Pacific Rim), ds.internic.net (US East Coast), or Europe), ftp.nis.garr.it (South Europe), munnari.oz.au (Pacific Rim),
ftp.isi.edu (US West Coast). ds.internic.net (US East Coast), or ftp.isi.edu (US West Coast).
Abstract Abstract
The Dynamic Host Configuration Protocol provides a framework for The Dynamic Host Configuration Protocol provides a framework for
passing configuration information to hosts on a TCP/IP network. passing configuration information to hosts on a TCP/IP network.
Entities using the Service Location Protocol need to find out the Entities using the Service Location Protocol need to find out the
address of Directory Agents in order to transact messages. In address of Directory Agents in order to transact messages. In
certain other instances they may need to discover the correct scope certain other instances they may need to discover the correct scope
and naming authority to be used in conjunction with the service to be used in conjunction with the service attributes and URLS which
attributes and URLS which are exchanged using the Service Location are exchanged using the Service Location Protocol.
Protocol.
1. Directory Agent Extension 1. Introduction
This extension specifies a Directory Agent (DA) [3], along with zero The Dynamic Host Configuration Protocol [2] provides a framework
or more Naming Authorities [2] known to that DA and zero or more for passing configuration information to hosts on a TCP/IP network.
scopes supported by that DA. Entities using the Service Location Protocol [3] need to find out
the address of Directory Agents in order to transact messages. In
certain other instances they may need to discover the correct scope
to be used in conjunction with the service attributes and URLs [1]
which are exchanged using the Service Location Protocol.
The code for this extension is 78. Each Naming Authority and each The scope MAY be denoted in any standardized character set. Values
scope MUST be a null-terminated string of ASCII characters. The for character encoding can be found in IANA's database
lengths of the strings are only indicated implicitly by their null http://www.isi.edu/in-notes/iana/assignments/character-sets
termination and the overall length of the extension. and have the values referred by the MIBEnum value.
Note that each option listed below may be included multiple times in
the same DHCPOFFER or DHCPREQUEST. If so, then the options SHOULD be
included in order of decreasing preference.
2. Directory Agent Option
This option requests or specifies a Directory Agent (DA), along with
zero or more scopes supported by that DA.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Length |D| NA count | scope count | | Code | Length |D|S| reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (if present) |
| Directory Agent address (16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NA list ... | (if present) Directory Agent address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| scope list ... | Char Encoding | scope ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code 78 Code 78
Length variable Length variable
D If the 'D' bit is set, the Directory Agent address is D If the 'D' bit is set, the Directory Agent address is
present. present.
NA count S If the 'S' bit is set, the scope is present, encoded in
The number of Naming Authorities indicated by strings in the indicated character set.
the NA list following.
scope count
The number of scopes indicated by strings in the scope
list following.
NA list Char Encoding
A list of strings denoting Naming Authorities. The standardized encoding for the characters making up
the string denoting the scope.
scope list scope A string denoting the scope.
A list of strings denoting scopes.
Note that more than one Directory Agent extension may be present in Note that more than one Directory Agent option may be present in a
a DHCP message. Each such extension may have the same or different DHCP message. Each such option may have the same or different scope.
lists of Naming Authorities and scopes. The client may request a The client may request any Directory Agent with a particular scope,
Directory Agent with a particular scope, and/or knowledgeable about by including the Directory Agent option in a DHCP Request message
schemes defined by a particular Naming Authority, by including the with no Directory Agent address included (the 'D' bit set to zero),
Directory Agent extension in a DHCP Request message with no Directory and the string denoting the scope. The length of the scope string is
Agent address included (the 'D' bit set to zero), and the appropriate only indicated implicitly by the overall length of the option.
strings in the NA list and/or scope list.
2. Service Scope Extension 3. Service Scope Option
This extension indicates a scope that should be used by a Service This option indicates a scope that should be used by a Service Agent
Agent (SA) [3], when responding to Service Request messages as (SA) [3], when responding to Service Request messages as specified by
specified by the Service Location Protocol. the Service Location Protocol.
Code Len 0 1 2 3
+-----+-----+-----+----- 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| 79 | n | Scope ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-----+-----+-----+----- | Code | Length | Char Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| scope ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Scope is a null-terminated ASCII string, of length 'n' including the Code 79
terminating null character.
3. Naming Authority Extension Length variable
This extension indicates a naming authority (which specifies the Char Encoding
syntax for schemes that may be used in URLs [1]) for use by entities The standardized encoding for the characters making up
with the Service Location Protocol. the string denoting the scope.
Code Len scope A string denoting the scope.
+-----+-----+-----+-----+-----+-----
| 80 | n | Naming Authority ...
+-----+-----+-----+-----+-----+-----
Naming Authority is a null-terminated ASCII string, of length 'n' Note that more than one Service Scope option may be present in a DHCP
including the terminating null character. message. The length of the scope string is only indicated implicitly
by the overall length of the option.
4. Security Considerations 4. Security Considerations
If a malicious host is able to insert fraudulent information in If a malicious host is able to insert fraudulent information in
DHCPOFFER packets sent to a prospective client of the Service DHCPOFFER packets sent to a prospective client of the Service
Location Protocol, then the client will be unable to obtain service, Location Protocol, then the client will be unable to obtain service,
and vulnerable to disclosing information to unauthorized service and vulnerable to disclosing information to unauthorized service
agents. Likewise, a service agent would find that it might rely on agents. Likewise, a service agent would find that it might rely on
fraudulent or otherwise malicious directory agents to advertise its fraudulent or otherwise malicious directory agents to advertise its
services. Many opportunities for denial of service exist. services. Many opportunities for denial of service exist.
skipping to change at page 3, line 20 skipping to change at page 3, line 22
5. Acknowledgements 5. Acknowledgements
Thanks to Erik Guttman for his helpful suggestions in the creation of Thanks to Erik Guttman for his helpful suggestions in the creation of
this draft. this draft.
References References
[1] T. Berners-Lee, L. Masinter, and M. McCahill. Uniform Resource [1] T. Berners-Lee, L. Masinter, and M. McCahill. Uniform Resource
Locators (URL). RFC 1738, December 1994. Locators (URL). RFC 1738, December 1994.
[2] Paul E. Hoffman and Ron Daniel, Jr. Generic URN Syntax. [2] Ralph Droms. Dynamic Host Configuration Protocol. RFC 1541,
draft-ietf-uri-urn-syntax-00.txt -- work in progress, April 1995. October 1993.
[3] J. Veizades, E. Guttman, C. Perkins, and S. Kaplan. Service [3] J. Veizades, E. Guttman, C. Perkins, and S. Kaplan. Service
Location Protocol. draft-ietf-svrloc-protocol-14.txt - work in Location Protocol, November 1996. draft-ietf-svrloc-protocol-15.txt
progress, June 1996. (work in progress).
Author's Address Author's Address
Questions about this memo can be directed to: Questions about this memo can be directed to:
Charles Perkins Charles E. Perkins
Room J1-A25 Sun Microsystems
T. J. Watson Research Center 2550 Garcia Avenue
IBM Corporation Mountain View, CA 94043
30 Saw Mill River Rd.
Hawthorne, NY 10532
Work: +1 914 7847350 Phone: +1 415 336 7153
Fax: +1 914 7847007 Fax: +1 415 336 0670
E-mail: perk@watson.ibm.com
EMail: charliep@acm.org
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/