draft-ietf-dhc-dhcpv6-opt-timeconfig-01.txt		draft-ietf-dhc-dhcpv6-opt-timeconfig-02.txt
	Network Working Group A.K. Vijayabhaskar		Network Working Group A.K. Vijayabhaskar
	Internet-Draft Hewlett-Packard		Internet-Draft Hewlett-Packard
	Expires: November 10, 2002 10 May 2002		Expires: August 26, 2003 26 Feb 2003
	Time Configuration Options for DHCPv6		Time Configuration Options for DHCPv6
	draft-ietf-dhc-dhcpv6-opt-timeconfig-01.txt		draft-ietf-dhc-dhcpv6-opt-timeconfig-02.txt
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
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	This Internet-Draft will expire on August 17, 2002.		This Internet-Draft will expire on August 26, 2003.
	Copyright Notice		Copyright Notice
	Copyright (C) The Internet Society (2002). All Rights Reserved.		Copyright (C) The Internet Society (2003). All Rights Reserved.
	Abstract		Abstract
	This document describes the options for Time related configuration		This document describes the options for Time related configuration
	information in DHCPv6: NTP Servers and IEEE 1003.1 POSIX Timezone		information in DHCPv6: NTP Servers and Timezone specifier.
	specifier.
	1. Introduction		1. Introduction
	This document describes the options for time related configuration		This document describes the options for time related configuration
	information in DHCPv6 [4].		information in DHCPv6 [1].
	2. Requirements		2. Requirements
	The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,		The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
	SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this		SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
	document, are to be interpreted as described in RFC 2119 [1]		document, are to be interpreted as described in RFC 2119 [4]
	3. Terminology		3. Terminology
	This document uses terminology specific to IPv6 and DHCPv6 as defined		This document uses terminology specific to IPv6 and DHCPv6 as defined
	in section "Terminology" of the DHCP specification.		in section "Terminology" of the DHCP specification.
	4. Network Time Protocol (NTP) Servers option		4. Network Time Protocol (NTP) Servers option
	The Network Time Protocol Servers option provides a list of one or		The Network Time Protocol Servers option provides a list of one or
	more IP addresses of NTP [2] servers available to the client. The		more IP addresses of NTP [2] servers available to the client. The
	skipping to change at page 2, line 44		skipping to change at page 2, line 44
	| ... |		| ... |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	option-code: OPTION_NTP_SERVERS (tbd)		option-code: OPTION_NTP_SERVERS (tbd)
	option-len: Length of the 'NTP server' fields in octets; It must be		option-len: Length of the 'NTP server' fields in octets; It must be
	a multiple of 16		a multiple of 16
	NTP server: IP address of NTP server		NTP server: IP address of NTP server
	5. IEEE 1003.1 POSIX Timezone option		5. Timezone option
	The IEEE 1003.1 POSIX Timezone option is used by the server to		The Timezone option is used by the server to convey client's timezone
	convey client's timezone information to the client.		information to the client.
	The format of the IEEE 1003.1 POSIX Timezone option is:		The format of the Timezone option is:
	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
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| OPTION_TIME_ZONE | option-len |		| OPTION_TIME_ZONE | option-len |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	| time-zone |		| time-zone |
	| ... |		| ... |
	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+		+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
	option-code: OPTION_TIME_ZONE (tbd)		option-code: OPTION_TIME_ZONE (tbd)
	option-len: Length of the 'time-zone' field in octets		option-len: Length of the 'time-zone' field in octets
	time-zone: Time zone of the client in IEEE 1003.1 POSIX Timezone		time-zone: Time zone of the client in the format as explained below.
	format [3].
	The format of the IEEE 1003.1 POSIX timezone string is specified as
	follows:
	StdOffset[Dst[Offset],[Start[/Time],End[/Time]]]		Std[Offset[Dst[Offset],[Start[/Time],End[/Time]]]]
	where '[' and ']' enclose optional fields, '|' indicates choice		where '[' and ']' enclose optional fields, '|' indicates choice
	of exactly one of the alternatives, ',' and '/' represent literal		of exactly one of the alternatives, ',' and '/' represent literal
	characters present in the string.		characters present in the string.
			If "Offset" is specified, then the time-zone is represented in the
			IEEE 1003.1 POSIX timezone format [3].
	Std Three or more octets for the standard timezone (Std).		Std Three or more octets for the standard timezone (Std).
	Any character (or case) except a leading colon, digits,		Any character (or case) except a leading colon, digits,
	comma, minus or plus sign is allowed.		comma, minus or plus sign is allowed. If the time-zone
			is not represented in IEEE 1003.1 POSIX timezone format [3],
			then Std is treated as the index to the timezone database,
			for example, a file name, from where additional information
			about the timezone may be obtained.
	Offset Indicates the value one must add to local time to		Offset Indicates the value one must add to local time to
	arrive at UTC, of the form: [+|-]hh[:mm[:ss]]. Offset		arrive at UTC, of the form: [+|-]hh[:mm[:ss]]. Offset
	following Std is required. Digits are always interpreted		following Std is required, if the timezone is represented
	as decimal number. If preceded by a '-', the timezone is		in IEEE 1003.1 POSIX timezone format. Digits are always
	east of the Prime Meridian, otherwise it is west ('+' is		interpreted as decimal number. If preceded by a '-', the
	optional) The permissible values for hh[:mm[:ss]] are as		timezone is east of the Prime Meridian, otherwise it is west
	follows:		('+' is optional) The permissible values for hh[:mm[:ss]] are
			as follows:
	hh 0 <= hh <= 23		hh 0 <= hh <= 23
	mm 0 <= mm <= 60		mm 0 <= mm <= 60
	ss 0 <= ss <= 60		ss 0 <= ss <= 60
	Offset has no default value.
	Dst Three or more octets for the daylight savings timezone.		Dst Three or more octets for the daylight savings timezone.
	If Dst is missing, then daylight savings time does not		If Dst is missing, then daylight savings time does not
	apply in this locale. If no Offset follows Dst, then		apply in this locale. If no Offset follows Dst, then
	Dst is assumed to be one hour ahead of standard time.		Dst is assumed to be one hour ahead of standard time.
	Any character (or case) except a leading colon, digits,		Any character (or case) except a leading colon, digits,
	comma, minus or plus sign is allowed.		comma, minus or plus sign is allowed.
	Start Indicates the day of the year, in one of the formats		Start Indicates the day of the year, in one of the formats
	indicated below, when to change to daylight savings time.		indicated below, when to change to daylight savings time.
	The ``Time'' field (which follows immediately after a		The ``Time'' field (which follows immediately after a
	skipping to change at page 4, line 22		skipping to change at page 4, line 28
	Jn The julian day n, (1 <= n <= 365). Leap days are not		Jn The julian day n, (1 <= n <= 365). Leap days are not
	counted.		counted.
	n Zero-based julian day, (0 <= n <= 365). Leap days are		n Zero-based julian day, (0 <= n <= 365). Leap days are
	counted so it is possible to refer to Feb 29.		counted so it is possible to refer to Feb 29.
	Mm.n.d The ``d''th day, (0 <= d <= 6) of week ``n'' of month		Mm.n.d The ``d''th day, (0 <= d <= 6) of week ``n'' of month
	``m'' of the year (1 <= n <= 5, 1 <= m <= 12, where week		``m'' of the year (1 <= n <= 5, 1 <= m <= 12, where week
	5 means last ``d'' day in month ``m'' which may occur in		5 means last ``d'' day in month ``m'' which may occur in
	either the fourth or the fifth week. Week ``1'' is the		either the fourth or the fifth week. Week ``1'' is the
	first week in which the ``d'' day occurs.		first week in which the ``d'' day occurs. Day ``0'' refers
			Sunday, day ``1'' refers Monday and so on.
	An Example:		Examples:
	For Eastern USA time zone, 1986, the Posix timezone string is as		i) Indian Standard Time zone is represented as:
	shown below:
			IST-5:30
			Here, ``IST'' refers the standard timezone and ``-5:30'' is the offset.
			`-' sign in the offset says that the timezone is 5 hours and 30 minutes
			ahead of UTC. Absence of ``Dst'' says that daylight savings doesn't apply
			to this locale.
			ii) For Eastern USA time zone, 1986, the timezone string is as shown below:
	EST5EDT4,116/02:00:00,298/02:00:00		EST5EDT4,116/02:00:00,298/02:00:00
	In this case, ``5'' is the Offset for Std, and ``4'' is the Offset		It says:
	for Dst. Start is the 116th day at 2am, and End is 298th day at 2am.
			The standard time zone is in 5 hours behind UTC. The Daylight Savings
			Timezone is 4 hours behind UTC. Day light savings starts at 116 day, i.e.,
			April 27 02:00 AM standard time and ends at 298th day, i.e., October 26
			02:00 AM daylight time.
			It can also represented as:
			EST5EDT,116/02:00:00,298/02:00:00
			Since no offset follows the ``Dst'', daylight savings time is 1 hour
			ahead of standard time, thus, it is 4 hours behind UTC.
			iii) Representing ii) in the non POSIX standard way is:
			America/New-York
			It says that the locale belongs to New-York timezone in America, which
			will be used as the index in to a timezone database to get more
			information of the timezone.
	6. Appearance of these option		6. Appearance of these option
	The NTP servers and IEEE 1003.1 POSIX Timezone options MUST appear		The NTP servers and Timezone options MUST appear only in the following
	only in the following messages: Solicit, Advertise, Request,		messages: Solicit, Advertise, Request, Confirm, Renew, Rebind,
	Confirm, Renew, Rebind, Information-Request, Reply.		Information-Request and Reply.
			The option number for these options MAY appear in the Option Request
			Option [1] in the following messages: Solicit, Request, Confirm, Renew,
			Rebind, Information-Request and Reconfigure.
	7. Security Considerations		7. Security Considerations
	The NTP servers option may be used by an intruder DHCP server to		The NTP servers option may be used by an intruder DHCP server to
	cause DHCP clients to contact an intruder NTP server, resulting in		cause DHCP clients to contact an intruder NTP server, resulting in
	invalid synchronization of time in client and finally leading to		invalid synchronization of time in client and finally leading to
	time critical applications running inaccurately in client machine.		time critical applications running inaccurately in client machine.
			The time accuracy can be crucial to some security algorithms. For
			example, it may cause expired certificates to gain a new life, making
			the application less secured.
	The IEEE 1003.1 POSIX Timezone option may be used by an intruder		The Timezone option may be used by an intruder DHCP server to assign
	DHCP server to assign invalid time zones, leading to timing issues		invalid time zones, leading to timing issues for the applications running
	for the applications running on the client machine.		on the client machine.
	To avoid attacks through these options, the DHCP client SHOULD use		To avoid attacks through these options, the DHCP client SHOULD use
	authenticated DHCP (see section "Authentication of DHCP messages"		authenticated DHCP (see section "Authentication of DHCP messages"
	in the DHCPv6 specification [4]).		in the DHCPv6 specification [1]).
	8. IANA Considerations		8. IANA Considerations
	IANA is requested to assign an option code to these options from the		IANA is requested to assign an option code to these options from the
	option-code space defined in section "DHCPv6 Options" of the DHCPv6		option-code space defined in section "DHCPv6 Options" of the DHCPv6
	specification [4].		specification [1].
	References		9. Normative References
	[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement		[1] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R.
	Levels", BCP 14, RFC 2119, March 1997.		Droms (ed.), "Dynamic Host Configuration Protocol for IPv6
			(DHCPv6)", draft-ietf-dhc-dhcpv6-28 (work in progress), November
			2002.
			10. Informative References
	[2] D. Mills. Simple Network Time Protocol (SNTP) Version 4 for		[2] D. Mills. Simple Network Time Protocol (SNTP) Version 4 for
	IPv4, IPv6 and OSI. Request for Comments (Informational) 2030,		IPv4, IPv6 and OSI. Request for Comments (Informational) 2030,
	Internet Engineering Task Force, October 1996.		Internet Engineering Task Force, October 1996.
	[3] IEEE, "1003.1 POSIX Timezone Specification", 1988.		[3] IEEE, "1003.1 POSIX Timezone Specification", 1988.
	[4] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R.		[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
	Droms (ed.), "Dynamic Host Configuration Protocol for IPv6		Levels", BCP 14, RFC 2119, March 1997.
	(DHCPv6)", draft-ietf-dhc-dhcpv6-23 (work in progress), February
	2002.
	Author's Addresses		Author's Addresses
	Vijayabhaskar A K		Vijayabhaskar A K
	Hewlett-Packard ESD-I		Hewlett-Packard ESD-I
	29, Cunningham Road		29, Cunningham Road
	Bangalore - 560052		Bangalore - 560052
	India		India
	Phone: +91-80-2051424		Phone: +91-80-2053085
	E-Mail: vijayak@india.hp.com		E-Mail: vijayak@india.hp.com
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The Internet Society (2002). All Rights Reserved.		Copyright (C) The Internet Society (2003). All Rights Reserved.
	This document and translations of it may be copied and furnished to		This document and translations of it may be copied and furnished to
	others, and derivative works that comment on or otherwise explain it		others, and derivative works that comment on or otherwise explain it
	or assist in its implementation may be prepared, copied, published		or assist in its implementation may be prepared, copied, published
	and distributed, in whole or in part, without restriction of any		and distributed, in whole or in part, without restriction of any
	kind, provided that the above copyright notice and this paragraph are		kind, provided that the above copyright notice and this paragraph are
	included on all such copies and derivative works. However, this		included on all such copies and derivative works. However, this
	document itself may not be modified in any way, such as by removing		document itself may not be modified in any way, such as by removing
	the copyright notice or references to the Internet Society or other		the copyright notice or references to the Internet Society or other
	Internet organizations, except as needed for the purpose of		Internet organizations, except as needed for the purpose of
	skipping to change at page 6, line 37		skipping to change at page 7, line 37
	"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING		"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
	TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING		TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
	BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION		BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
	HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF		HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
	MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.		MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	Acknowledgement		Acknowledgement
	Funding for the RFC Editor function is currently provided by the		Funding for the RFC Editor function is currently provided by the
	Internet Society. Thanks to the DHC Working Group for their time and		Internet Society. Thanks to the DHC Working Group for their time and
	input into the specification. In particular, thanks to Jim Bound and		input into the specification. In particular, thanks to (in alphabetical
	Ralph Droms for their thorough review. Thanks to Mike Carney for his		order) Bernie Volz, Jim Bound, Ralph Droms, Robert Elz for their thorough
	abstract on Time Zone option.		review. Special thanks to Robert Elz for his suggestions and help in
			making this document more readable. Thanks to Mike Carney for his abstract
			on Time Zone option.
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