draft-ietf-radext-dtls-00.txt		draft-ietf-radext-dtls-01.txt
	Network Working Group Alan DeKok		Network Working Group Alan DeKok
	INTERNET-DRAFT FreeRADIUS		INTERNET-DRAFT FreeRADIUS
	Category: Informational		Category: Informational
	<draft-ietf-radext-dtls-00.txt>		<draft-ietf-radext-dtls-01.txt>
	Expires: April 8, 2011		Expires: April 12, 2011
	8 October 2010		12 October 2010
	DTLS as a Transport Layer for RADIUS		DTLS as a Transport Layer for RADIUS
	draft-ietf-radext-dtls-00		draft-ietf-radext-dtls-01
	Abstract		Abstract
	The RADIUS protocol [RFC2865] has limited support for authentication		The RADIUS protocol [RFC2865] has limited support for authentication
	and encryption of RADIUS packets. The protocol transports data "in		and encryption of RADIUS packets. The protocol transports data "in
	the clear", although some parts of the packets can have "hidden"		the clear", although some parts of the packets can have "hidden"
	content. Packets may be replayed verbatim by an attacker, and		content. Packets may be replayed verbatim by an attacker, and
	client-server authentication is based on fixed shared secrets. This		client-server authentication is based on fixed shared secrets. This
	document specifies how the Datagram Transport Layer Security (DTLS)		document specifies how the Datagram Transport Layer Security (DTLS)
	protocol may be used as a fix for these problems. It also describes		protocol may be used as a fix for these problems. It also describes
	skipping to change at page 1, line 46		skipping to change at page 1, line 46
	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 April 8, 2011		This Internet-Draft will expire on April 12, 2011
	Copyright Notice		Copyright Notice
	Copyright (c) 2010 IETF Trust and the persons identified as the		Copyright (c) 2010 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info/) in effect on the date of		(http://trustee.ietf.org/license-info/) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	skipping to change at page 3, line 26		skipping to change at page 3, line 26
	3.1. Protocol Disambiguation ............................. 9		3.1. Protocol Disambiguation ............................. 9
	4. Connection Management .................................... 10		4. Connection Management .................................... 10
	4.1. Server Connection Management ........................ 10		4.1. Server Connection Management ........................ 10
	4.1.1. Table Management ............................... 10		4.1.1. Table Management ............................... 10
	4.2. Client Connection Management ........................ 11		4.2. Client Connection Management ........................ 11
	5. Processing Algorithm ..................................... 12		5. Processing Algorithm ..................................... 12
	6. Diameter Considerations .................................. 14		6. Diameter Considerations .................................. 14
	7. IANA Considerations ...................................... 14		7. IANA Considerations ...................................... 14
	8. Security Considerations .................................. 14		8. Security Considerations .................................. 14
	8.1. Legacy RADIUS Security .............................. 14		8.1. Legacy RADIUS Security .............................. 14
	9. References ............................................... 15		8.2. Network Address Translation ......................... 15
	9.1. Normative references ................................ 15		9. References ............................................... 16
	9.2. Informative references .............................. 16		9.1. Normative references ................................ 16
			9.2. Informative references .............................. 17
	1. Introduction		1. Introduction
	The RADIUS protocol as described in [RFC2865], [RFC2866], and		The RADIUS protocol as described in [RFC2865], [RFC2866], and
	[RFC5176] has traditionally used methods based on MD5 [RFC1321] for		[RFC5176] has traditionally used methods based on MD5 [RFC1321] for
	per-packet authentication and integrity checks. However, the MD5		per-packet authentication and integrity checks. However, the MD5
	algorithm has known weaknesses such as [MD5Attack] and [MD5Break].		algorithm has known weaknesses such as [MD5Attack] and [MD5Break].
	As a result, previous specifications such as [RFC5176] have		As a result, previous specifications such as [RFC5176] have
	recommended using IPSec to secure RADIUS traffic.		recommended using IPSec to secure RADIUS traffic.
	skipping to change at page 15, line 45		skipping to change at page 15, line 45
	cryptographically secure pseudo-random number generator (CSPRNG).		cryptographically secure pseudo-random number generator (CSPRNG).
	For example, a reasonable key may be 32 characters of a SHA-256 hash		For example, a reasonable key may be 32 characters of a SHA-256 hash
	of at least 64 bytes of data taken from a CSPRNG. If this method		of at least 64 bytes of data taken from a CSPRNG. If this method
	seems too complicated, a certificate-based TLS method SHOULD be used		seems too complicated, a certificate-based TLS method SHOULD be used
	instead.		instead.
	The previous RADIUS practice of using shared secrets that are minor		The previous RADIUS practice of using shared secrets that are minor
	variations of words is NOT RECOMMENDED, as it would negate nearly all		variations of words is NOT RECOMMENDED, as it would negate nearly all
	of the security of DTLS.		of the security of DTLS.
			8.2. Network Address Translation
			Network Address Translation (NAT) is fundamentally incompatible with
			RADIUS. RADIUS uses the source IP address to determine the shared
			secret for the client, and NAT hides many clients behind one source
			IP address.
			The migration flag described above in Section 3 is also tracked per
			source IP address. Using a NAT in front of many RADIUS clients
			negates the function of the flag, making it impossible to migrate
			clients in a secure fashion.
			In addition, port re-use on a NAT gateway means that packets from
			different clients may appear to come from the same source port on the
			NAT. That is, a RADIUS server may receive a RADIUS/DTLS packet from
			a client IP/port combination, followed by the reception of a
			RADIUS/UDP packet from that same client IP/port combination. If this
			capability were allowed, it would permit a downgrade attack to occur,
			and would negate all of the security added by RADIUS/DTLS.
			As a result, RADIUS clients SHOULD NOT be located behind a NAT
			gateway. If clients are located behind a NAT gateway, then a secure
			transport such as DTLS MUST be used.
	9. References		9. References
	9.1. Normative references		9.1. Normative references
	[RFC2865]		[RFC2865]
	Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote		Rigney, C., Willens, S., Rubens, A. and W. Simpson, "Remote
	Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.		Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000.
	[RFC3539]		[RFC3539]
	Aboba, B. et al., "Authentication, Authorization and Accounting		Aboba, B. et al., "Authentication, Authorization and Accounting
End of changes. 5 change blocks.
	8 lines changed or deleted		33 lines changed or added
This html diff was produced by rfcdiff 1.40. The latest version is available from http://tools.ietf.org/tools/rfcdiff/