draft-ietf-dnsop-reflectors-are-evil-05.txt		draft-ietf-dnsop-reflectors-are-evil-06.txt
	Network Working Group J. Damas		Network Working Group J. Damas
	Internet-Draft ISC		Internet-Draft ISC
	Intended status: Best Current F. Neves		Intended status: BCP F. Neves
	Practice Registro.br		Expires: March 5, 2009 Registro.br
	Expires: June 5, 2008 December 3, 2007		September 1, 2008
	Preventing Use of Recursive Nameservers in Reflector Attacks		Preventing Use of Recursive Nameservers in Reflector Attacks
	draft-ietf-dnsop-reflectors-are-evil-05.txt		draft-ietf-dnsop-reflectors-are-evil-06.txt
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
	skipping to change at page 1, line 35		skipping to change at page 1, line 35
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on June 5, 2008.		This Internet-Draft will expire on March 5, 2009.
	Copyright Notice
	Copyright (C) The IETF Trust (2007).
	Abstract		Abstract
	This document describes ways to prevent the use of default configured		This document describes ways to prevent the use of default configured
	recursive nameservers as reflectors in Denial of Service (DoS)		recursive nameservers as reflectors in Denial of Service (DoS)
	attacks. Recommended configuration as measures to mitigate the		attacks. Recommended configuration as measures to mitigate the
	attack are given.		attack are given.
	Table of Contents		Table of Contents
	skipping to change at page 4, line 7		skipping to change at page 4, line 7
	3. Problem Description		3. Problem Description
	Because most DNS traffic is stateless by design, an attacker could		Because most DNS traffic is stateless by design, an attacker could
	start a DoS attack in the following way:		start a DoS attack in the following way:
	1. The attacker starts by configuring a record on any zone he has		1. The attacker starts by configuring a record on any zone he has
	access to, normally with large RDATA and TTL.		access to, normally with large RDATA and TTL.
	2. Taking advantage of clients on non-BCP38 networks, the attacker		2. Taking advantage of clients on non-BCP38 networks, the attacker
	then crafts a query using the source address of their target		then crafts a query using the source address of their target
	victim and sends it to an open recursive nameserver (ORNS).		victim and sends it to an open recursive nameserver.
	3. Each open recursive nameserver proceeds with the resolution,		3. Each open recursive nameserver proceeds with the resolution,
	caches the record and finally sends it to the target. After this		caches the record and finally sends it to the target. After this
	first lookup, access to the authoritative nameservers is normally		first lookup, access to the authoritative nameservers is normally
	no longer necessary. The record will remain cached for the		no longer necessary. The record will remain cached for the
	duration of the TTL at the open recursive nameserver even if it's		duration of the TTL at the open recursive nameserver even if it's
	deleted from the zone.		deleted from the zone.
	4. Cleanup of the zone might, depending on the implementation used		4. Cleanup of the zone might, depending on the implementation used
	in the open recursive nameserver, afford a way to clean the		in the open recursive nameserver, afford a way to clean the
	cached record from the open recursive nameserver. This would		cached record from the open recursive nameserver. This would
	possibly involve queries luring the open recursive nameserver to		possibly involve queries luring the open recursive nameserver to
	skipping to change at page 4, line 50		skipping to change at page 4, line 50
	knit community, some nameserver implementations have been made		knit community, some nameserver implementations have been made
	available with default configurations that when used for recursive		available with default configurations that when used for recursive
	nameservers made the server accessible to all hosts on the Internet.		nameservers made the server accessible to all hosts on the Internet.
	For years this was a convenient and helpful configuration, enabling		For years this was a convenient and helpful configuration, enabling
	wider availability of services. As this document aims to make		wider availability of services. As this document aims to make
	apparent, it is now much better to be conscious of ones own		apparent, it is now much better to be conscious of ones own
	nameserver services and focus the delivery of services on the		nameserver services and focus the delivery of services on the
	intended audience of those services, be they a university campus, an		intended audience of those services, be they a university campus, an
	enterprise or an ISP's customers. The target audience also includes		enterprise or an ISP's customers. The target audience also includes
	operators of small network operators and private server managers who		operators of small networks and private server managers who decide to
	decide to operate nameservers with the aim of optimising their DNS		operate nameservers with the aim of optimising their DNS service, as
	service, as these are more likely to use default configurations as		these are more likely to use default configurations as shipped by
	shipped by implementors.		implementors.
	4. Recommended Configuration		4. Recommended Configuration
	In this section we describe the Best Current Practice for operating		In this section we describe the Best Current Practice for operating
	recursive nameservers. Following these recommendations would reduce		recursive nameservers. Following these recommendations would reduce
	the chances of having a given recursive nameserver be used for the		the chances of having a given recursive nameserver be used for the
	generation of an amplification attack.		generation of an amplification attack.
	The generic recommendation to nameserver operators is to use the		The generic recommendation to nameserver operators is to use the
	means provided by the implementation of choice to provide recursive		means provided by the implementation of choice to provide recursive
	skipping to change at page 6, line 19		skipping to change at page 6, line 19
	Multihomed Network" [BCP84] maybe a useful additional reference.		Multihomed Network" [BCP84] maybe a useful additional reference.
	By default, nameservers SHOULD NOT offer recursive service to		By default, nameservers SHOULD NOT offer recursive service to
	external networks.		external networks.
	5. Security Considerations		5. Security Considerations
	This document does not create any new security issues for the DNS		This document does not create any new security issues for the DNS
	protocol, it deals with a weakness in implementations.		protocol, it deals with a weakness in implementations.
			Deployment of SIG(0) transaction security should consider the caveats
			with SIG(0) computational expense as it uses public key cryptography
			rather than the symmetric keys used by TSIG. In addition, the
			identification of the appropriate keys needs similar mechanisms to
			those for deploying TSIG, or alternatively, the use of DNSSEC
			signatures (RRSIGs) over the KEY RRs if published in DNS. This will
			in turn require the appropriate management of DNSSEC trust anchors.
	6. Acknowledgments		6. Acknowledgments
	The authors would like to acknowledge the helpful input and comments		The authors would like to acknowledge the helpful input and comments
	of Joe Abley, Olafur Gudmundsson, Pekka Savola, Andrew Sullivan and		of Joe Abley, Olafur Gudmundsson, Pekka Savola, Andrew Sullivan and
	Tim Polk.		Tim Polk.
	7. IANA Considerations		7. IANA Considerations
	This document does not define a registry and does not require any		This document does not define a registry and does not require any
	IANA action.		IANA action.
	skipping to change at page 8, line 7		skipping to change at page 8, line 7
	Av. das Nacoes Unidas, 11541, 7		Av. das Nacoes Unidas, 11541, 7
	Sao Paulo, SP 04578-000		Sao Paulo, SP 04578-000
	BR		BR
	Phone: +55 11 5509 3511		Phone: +55 11 5509 3511
	Email: fneves@registro.br		Email: fneves@registro.br
	URI: http://registro.br/		URI: http://registro.br/
	Full Copyright Statement		Full Copyright Statement
	Copyright (C) The IETF Trust (2007).		Copyright (C) The IETF Trust (2008).
	This document is subject to the rights, licenses and restrictions		This document is subject to the rights, licenses and restrictions
	contained in BCP 78, and except as set forth therein, the authors		contained in BCP 78, and except as set forth therein, the authors
	retain all their rights.		retain all their rights.
	This document and the information contained herein are provided on an		This document and the information contained herein are provided on an
	"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS		"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
	OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND		OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
	THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS		THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
	OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF		OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
	skipping to change at page 8, line 44		skipping to change at line 323
	attempt made to obtain a general license or permission for the use of		attempt made to obtain a general license or permission for the use of
	such proprietary rights by implementers or users of this		such proprietary rights by implementers or users of this
	specification can be obtained from the IETF on-line IPR repository at		specification can be obtained from the IETF on-line IPR repository at
	http://www.ietf.org/ipr.		http://www.ietf.org/ipr.
	The IETF invites any interested party to bring to its attention any		The IETF invites any interested party to bring to its attention any
	copyrights, patents or patent applications, or other proprietary		copyrights, patents or patent applications, or other proprietary
	rights that may cover technology that may be required to implement		rights that may cover technology that may be required to implement
	this standard. Please address the information to the IETF at		this standard. Please address the information to the IETF at
	ietf-ipr@ietf.org.		ietf-ipr@ietf.org.
	Acknowledgment
	Funding for the RFC Editor function is provided by the IETF
	Administrative Support Activity (IASA).
End of changes. 8 change blocks.
	15 lines changed or deleted		19 lines changed or added
This html diff was produced by rfcdiff 1.34. The latest version is available from http://tools.ietf.org/tools/rfcdiff/