draft-ietf-dhc-slp-01.txt   draft-ietf-dhc-slp-02.txt 
Internet Engineering Task Force C. Perkins Internet Engineering Task Force C. Perkins
INTERNET DRAFT IBM INTERNET DRAFT Sun Microsystems
14 March 1997 24 April 1997
DHCP Options for Service Location Protocol DHCP Options for Service Location Protocol
draft-ietf-dhc-slp-01.txt draft-ietf-dhc-slp-02.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-v4@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
skipping to change at page 1, line 41 skipping to change at page 1, line 41
Europe), ftp.nis.garr.it (South Europe), munnari.oz.au (Pacific Rim), Europe), ftp.nis.garr.it (South Europe), munnari.oz.au (Pacific Rim),
ds.internic.net (US East Coast), or 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
to be used in conjunction with the service attributes and URLS which to be used in conjunction with the service attributes which are
are exchanged using the Service Location Protocol. exchanged using the Service Location Protocol.
1. Introduction 1. Introduction
The Dynamic Host Configuration Protocol [2] provides a framework The Dynamic Host Configuration Protocol [2] provides a framework
for passing configuration information to hosts on a TCP/IP network. for passing configuration information to hosts on a TCP/IP network.
Entities using the Service Location Protocol [3] need to find out Entities using the Service Location Protocol [3] need to find out
the address of Directory Agents in order to transact messages. In the 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
to be used in conjunction with the service attributes and URLs [1] to be used in conjunction with the service attributes which are
which are exchanged using the Service Location Protocol. exchanged using the Service Location Protocol.
The scope MAY be denoted in any standardized character set. Values The scope MAY be denoted in any standardized character set. Values
for character encoding can be found in IANA's database for character encoding can be found in IANA's database
http://www.isi.edu/in-notes/iana/assignments/character-sets http://www.isi.edu/in-notes/iana/assignments/character-sets
and have the values referred by the MIBEnum value. and have the values referred by the MIBEnum value. Note that in some
character sets, each character may require two or more octets of data
for its representation.
Note that each option listed below may be included multiple times in Note that each option listed below MAY be included multiple times in
the same DHCPOFFER or DHCPREQUEST. If so, then the options SHOULD be the same DHCPOFFER or DHCPREQUEST. If so, then the options SHOULD be
included in order of decreasing preference. included in order of decreasing preference.
2. Directory Agent Option 2. Directory Agent Option
This option requests or specifies a Directory Agent (DA), along with This option requests or specifies a Directory Agent (DA), along with
zero or more scopes supported by that DA. 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|S| reserved | | Code | Length |D|F|M|S| rsv | DA Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (if present) Directory Agent address | | Directory Agent (variable length) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Char Encoding | scope ... | Char Encoding | Service Scope (variable length)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code 78 Code 78
Length variable Length (variable) The length of the option.
D If the 'D' bit is set, the Directory Agent address is D If the 'D' bit is set, the Directory Agent field is
present. present.
F If the 'F' bit is set, the Directory Agent is indicated
by including its variable length host name or Fully
Qualified Domain Name (FQDN) instead of its 4 octet IP
address.
M If the 'M' bit is set, the Directory Agent address is
the only one that may be used, and multicast methods for
discovering Directory Agents MUST NOT be used.
S If the 'S' bit is set, the scope is present, encoded in S If the 'S' bit is set, the scope is present, encoded in
the indicated character set. the indicated character set.
rsv reserved; ignored upon reception; MUST be sent as zero
DA Length The length (in octets) of the Directory Agent field.
Directory Agent
The Fully Qualified Domain Name (FQDN), host name, or IP
address of the Directory Agent.
Char Encoding Char Encoding
The standardized encoding for the characters making up The standardized encoding for the characters denoting the
the string denoting the scope. scope.
scope A string denoting the scope. scope The characters denoting the scope.
In order to simplify administration of the configuration of Directory
Agents for Service Location Protocol clients, the Directory Agent
can be indicated by presenting its FQDN or host name instead of its
IP address. This allows renumbering to proceed more smoothly [1].
When the FQDN or host name is used, the server sets the 'F' bit. The
host name can be distinguished from the FQDN by the presence of a '.'
character. In any case, the DA length field is set to be the length
of the Directory Agent field. When the 'F' bit is not set, the DA
Length MUST be 4.
Note that more than one Directory Agent option may be present in a Note that more than one Directory Agent option may be present in a
DHCP message. Each such option may have the same or different scope. DHCP message. Each such option may have the same or different scope.
The client may request any Directory Agent with a particular scope, The client may request any Directory Agent with a particular scope,
by including the Directory Agent option in a DHCP Request message by including the Directory Agent option in a DHCP Request message
with no Directory Agent address included (the 'D' bit set to zero), with no Directory Agent address included (the 'D' bit set to zero),
and the string denoting the scope. The length of the scope string is and the characters denoting the scope. The length of the scope is
only indicated implicitly by the overall length of the option. only indicated implicitly by the overall length of the option.
3. Service Scope Option 3. Service Scope Option
This option indicates a scope that should be used by a Service Agent This option indicates a scope that should be used by a Service Agent
(SA) [3], when responding to Service Request messages as specified by (SA) [3], when responding to Service Request messages as specified by
the Service Location Protocol. the Service Location Protocol.
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 | Char Encoding | | Code | Length | Char Encoding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| scope ... | Service Scope ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Code 79 Code 79
Length variable Length (variable) The length of the option.
Char Encoding Char Encoding
The standardized encoding for the characters making up The standardized encoding for the characters denoting the
the string denoting the scope. scope.
scope A string denoting the scope. scope the characters denoting the scope.
Note that more than one Service Scope option may be present in a DHCP Note that more than one Service Scope option may be present in a DHCP
message. The length of the scope string is only indicated implicitly message. The length of the scope is only indicated implicitly by the
by the overall length of the option. 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 19 skipping to change at page 3, line 46
from a DHCP server (or client!) is not possible in common DHCP from a DHCP server (or client!) is not possible in common DHCP
deployments. deployments.
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] B. Carpenter and Y. Rekhter. Renumbering needs work. RFC 1900,
Locators (URL). RFC 1738, December 1994. February 1996.
[2] Ralph Droms. Dynamic Host Configuration Protocol. RFC 1541, [2] Ralph Droms. Dynamic Host Configuration Protocol. RFC 1541,
October 1993. 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, November 1996. draft-ietf-svrloc-protocol-15.txt Location Protocol, April 1997. draft-ietf-svrloc-protocol-17.txt
(work in progress). (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 E. Perkins Charles E. Perkins
Sun Microsystems Sun Microsystems
2550 Garcia Avenue 2550 Garcia Avenue
Mountain View, CA 94043 Mountain View, CA 94043
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