DHCPv6 NIS Options: Network Information Service (NIS) Configuration Options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
Four DHCPv6 options that tell IPv6 clients which NIS or NIS+ servers and domain names to use.
Kalusivalingam, V., "Network Information Service (NIS) Configuration Options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3898, DOI 10.17487/RFC3898, October 2004, <https://www.rfc-editor.org/info/rfc3898>.
@misc{rfc3898,
series = {Request for Comments},
number = 3898,
howpublished = {RFC 3898},
publisher = {RFC Editor},
doi = {10.17487/RFC3898},
url = {https://www.rfc-editor.org/info/rfc3898},
author = {V. Kalusivalingam},
title = {{Network Information Service (NIS) Configuration Options for Dynamic Host Configuration Protocol for IPv6 (DHCPv6)}},
pagetotal = 7,
year = 2004,
month = oct,
} RFC text
Contents
Network Working Group V. Kalusivalingam
Request for Comments: 3898 Cisco Systems (India) Private Limited
Category: Standards Track October 2004
Network Information Service (NIS)
Configuration Options for
Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
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.
Copyright Notice
Copyright (C) The Internet Society (2004).
Abstract
This document describes four options for Network Information Service
(NIS) related configuration information in Dynamic Host Configuration
Protocol for IPv6 (DHCPv6): NIS Servers, NIS+ Servers, NIS Client
Domain Name, NIS+ Client Domain name.
1. Introduction
This document describes four options for passing configuration
information related to Network Information Service (NIS) [3] in
DHCPv6 (RFC 3315 [1]).
The options defined in this document can only be used to configure
information about NIS servers that can be reached using IPv6. The
DHCP option to configure information about IPv4 NIS servers can be
found in RFC 2132 [4]. Mechanisms for configuring IPv4/IPv6 dual-
stack applications are being considered, but are not specified in
this document.
2. Terminology
The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be
interpreted as described in BCP 14, RFC 2119 [2].
Throughout this document, unless otherwise specified, the acronym
DHCP refers to DHCP as specified in RFC 3315.
This document uses terminology specific to IPv6 and DHCP as defined
in section "Terminology" of RFC 3315.
3. Network Information Service (NIS) Servers Option
The Network Information Service (NIS) Servers option provides a list
of one or more IPv6 addresses of NIS servers available to the client.
Clients MUST treat the list of NIS servers as an ordered list. The
server MAY list the NIS servers in the order of preference.
The format of the Network Information Service Servers option is as
shown below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_NIS_SERVERS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| NIS server (IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| NIS server (IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_NIS_SERVERS (27)
option-len: Length of the 'NIS server' fields in octets; It must be
a multiple of 16
NIS server: IPv6 address of NIS server
4. Network Information Service V2 (NIS+) Servers Option
The Network Information Service V2 (NIS+) Servers option provides a
list of one or more IPv6 addresses of NIS+ servers available to the
client. Clients MUST treat the list of NIS+ servers as an ordered
list. The server MAY list the NIS+ servers in the order of
preference.
The format of the Network Information Service V2 (NIS+) Servers
option is as shown below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_NISP_SERVERS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| NIS+ server (IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| NIS+ server (IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_NISP_SERVERS (28)
option-len: Length of the 'NIS+ server' fields in octets; It must be
a multiple of 16
NIS+ server: IPv6 address of NIS+ server
5. Network Information Service (NIS) Domain Name Option
The Network Information Service (NIS) Domain Name option is used by
the server to convey client's NIS Domain Name info to the client.
The format of the NIS Domain Name option is as shown below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_NIS_DOMAIN_NAME | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| nis-domain-name |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_NIS_DOMAIN_NAME (29)
option-len: Length of the 'nis-domain-name' field in octets
nis-domain-name: NIS Domain name for client
The 'nis-domain-name' MUST be encoded as specified in section
"Representation and Use of domain names" of the DHCPv6 specification
[1].
6. Network Information Service V2 (NIS+) Domain Name Option
The Network Information Service V2 (NIS+) Domain Name option is used
by the server to convey client's NIS+ Domain Name info to the client.
The format of the NIS+ Domain Name option is as shown below:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_NISP_DOMAIN_NAME | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| nisp-domain-name |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_NISP_DOMAIN_NAME (30)
option-len: Length of the 'nisp-domain-name' field in octets
nisp-domain-name: NIS+ Domain name for client
The 'nisp-domain-name' MUST be encoded as specified in section
"Representation and Use of domain names" of the DHCPv6 specification
[1].
7. Appearance of these Options
The NIS servers, NIS+ servers, NIS domain name and NIS+ domain name
options MUST NOT appear in other than the following messages:
Solicit, Advertise, Request, Renew, Rebind, Information-Request and
Reply.
The option number for these options MAY appear in the Option Request
Option [1] in the following messages: Solicit, Request, Renew,
Rebind, Information-Request and Reconfigure.
8. Security Considerations
The NIS servers, NIS+ servers, NIS domain name and NIS+ domain name
options may be used by an intruder DHCPv6 server to assign invalid
NIS parameters, resulting in clients unable to use NIS service.
The NIS servers and NIS+ servers options may be used by an intruder
DHCPv6 server to cause the DHCPv6 clients to send their queries to an
intruder NIS/NIS+ server. This misdirected searches may be used to
spoof NIS/NIS+ names.
The NIS domain name and NIS+ domain name options may be used by an
intruder DHCPv6 server to cause the DHCPv6 clients to search through
invalid domains for incompletely specified domain names. The results
of these misdirected searches may be used to spoof NIS/NIS+ names.
To avoid attacks through these options, the DHCPv6 client SHOULD use
authenticated DHCP (see section "Authentication of DHCP messages" in
the DHCPv6 specification [1]).
9. IANA Considerations
The IANA has assigned option codes to the following options from the
option-code space defined in "DHCPv6 Options" section of the DHCPv6
specification [1].
Option Name Value Described in
OPTION_NIS_SERVERS 27 Section 3
OPTION_NISP_SERVERS 28 Section 4
OPTION_NIS_DOMAIN_NAME 29 Section 5
OPTION_NISP_DOMAIN_NAME 30 Section 6
10. References
10.1. Normative References
[1] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, C., and
M. Carney, "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
10.2. Informative References
[3] Sun Microsystems, "System and Network Administration", March
1990.
[4] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
Acknowledgements
Thanks to the DHC Working Group for their time and input into the
specification. In particular, thanks to (in alphabetical order)
Bernie Volz, Jim Bound, Margaret Wasserman, Pekka Savola, Ralph
Droms, and Thomas Narten for their thorough review.
Author's Address
Vijayabhaskar A Kalusivalingam
Cisco Systems (India) Private Limited,
No: 9, Brunton Road,
Bangalore - 560025
India
Phone: +91-80-51036615
EMail: vibhaska@cisco.com
Full Copyright Statement
Copyright (C) The Internet Society (2004).
This document is subject to the rights, licenses and restrictions
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AI ELI5
On this page
§1Introduction and Scope
RFC 3898 describes four options for passing configuration related to the Network Information Service (NIS) in DHCPv6, which is specified in RFC 3315.
The options can only configure information about NIS servers that can be reached using IPv6. The DHCP option for IPv4 NIS servers is found in RFC 2132. The RFC says mechanisms for dual-stack IPv4/IPv6 applications are being considered but are not specified here.
Some computers look things up from a shared directory server. This note teaches the network to tell a new IPv6 computer where that directory is.
§2The Two Server-List Options
The NIS Servers option (OPTION_NIS_SERVERS, code 27) and the NIS+ Servers option (OPTION_NISP_SERVERS, code 28) have the same layout: an option code, an option-len field, and then one or more IPv6 addresses, one per server.
option-len is the length of the server fields in octets and must be a multiple of 16, since each IPv6 address takes 16 octets. Clients MUST treat the list as ordered, and the server MAY list the servers in order of preference.
It is a list of phone numbers for helper computers, written in the order you should try them.
§3The Two Domain Name Options
The NIS Client Domain Name option (OPTION_NIS_DOMAIN_NAME, code 29) and the NIS+ Client Domain Name option (OPTION_NISP_DOMAIN_NAME, code 30) let the server tell the client which NIS or NIS+ domain name it should use.
Each carries an option-len and then the domain name (nis-domain-name or nisp-domain-name). The name MUST be encoded as the DHCPv6 specification describes in its section on the representation and use of domain names.
This is the name of the group the computer belongs to, like the name of your school class, so it knows whose list to read.
§4Where the Options Appear
The four options MUST NOT appear in any DHCPv6 message other than Solicit, Advertise, Request, Renew, Rebind, Information-Request and Reply.
A client MAY list the option numbers in the Option Request Option in these messages: Solicit, Request, Renew, Rebind, Information-Request and Reconfigure.
There are only certain moments in the conversation when these notes may be passed, and the client can ask for them by number.
§5Security Considerations
An intruder DHCPv6 server could use these options to assign invalid NIS parameters, leaving clients unable to use NIS. It could also point clients at an intruder NIS or NIS+ server, and misdirected searches could be used to spoof NIS or NIS+ names.
The domain name options could make clients search invalid domains for incompletely specified names, with similar spoofing results. To avoid these attacks the DHCPv6 client SHOULD use authenticated DHCP.
A trickster could hand out a fake card with the wrong phone numbers. Checking who gave you the card helps.
§6IANA Option Codes
IANA assigned the four option codes from the option-code space defined in the DHCPv6 specification: 27, 28, 29 and 30, described in sections 3 to 6 of the RFC.
Each option got its own number in a big official list so everyone uses the same one.
- 27OPTION_NIS_SERVERS — List of IPv6 addresses of NIS servers.
- 28OPTION_NISP_SERVERS — List of IPv6 addresses of NIS+ servers.
- 29OPTION_NIS_DOMAIN_NAME — NIS domain name for the client.
- 30OPTION_NISP_DOMAIN_NAME — NIS+ domain name for the client.