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Hilliard 3 Internet-Draft INEX 4 Intended status: Informational October 10, 2011 5 Expires: April 12, 2012 7 A Discard Prefix for IPv6 8 draft-ietf-v6ops-ipv6-discard-prefix-00 10 Abstract 12 Remote triggered black hole filtering describes a method of 13 mitigating against denial-of-service attacks by selectively 14 discarding traffic based on source or destination address. This 15 document explains why a unique IPv6 prefix should be formally 16 assigned by IANA for the purpose of facilitating IPv6 remote 17 triggered black hole filtering. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on April 12, 2012. 36 Copyright Notice 38 Copyright (c) 2011 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3 55 2. A Discard Prefix for IPv6 . . . . . . . . . . . . . . . . . . . 3 56 3. Operational Implications . . . . . . . . . . . . . . . . . . . 4 57 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 58 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 59 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 60 6.1. Normative References . . . . . . . . . . . . . . . . . . . 4 61 6.2. Informative References . . . . . . . . . . . . . . . . . . 4 62 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 64 1. Introduction 66 Remote triggered black hole (RTBH) filtering describes a class of 67 methods of blocking IP traffic to or from a specific destination on a 68 network. These methods operate by setting the next-hop address of an 69 IP packet with a specified source or destination address to be a 70 unicast prefix which is wired locally or remotely to a router's 71 discard or null interface. Typically, this information is propagated 72 throughout an autonomous system using a dynamic routing protocol. By 73 deploying RTBH systems across a network, traffic to or from specific 74 destinations may be selectively black-holed in a manner which is 75 efficient, scalable and straightforward to implement. For IPv4, some 76 networks configure RTBH installations using [RFC1918] address space 77 or the address blocks reserved for documentation in [RFC5737]. 79 However RTBH configurations are not documentation, but operationally 80 important features of many public-facing production networks. 81 Furthermore, [RFC3849] specifies that the IPv6 documentation prefix 82 should be filtered in both local and public contexts. On this basis, 83 it is suggested that both private network address blocks and 84 documentation prefixes described in [RFC5737] are inappropriate for 85 the purpose of RTBH configurations. 87 While it could be argued that there are other addresses and address 88 prefixes which could be used for this purpose (e.g. ::/128), or that 89 an operator could assign an address block from their own address 90 space for this purposes, there is currently no operational clarity on 91 what address block would be appropriate or inappropriate to use for 92 this purpose. By creating an assigned discard prefix for IPv6, the 93 IETF will introduce operational clarity and good practice for 94 implementation of IPv6 RTBH configurations. 96 1.1. Conventions 98 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 99 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 100 document are to be interpreted as described in [RFC2119]. 102 2. A Discard Prefix for IPv6 104 For the purposes of implementing an IPv6 remote triggered black hole 105 filter, a unicast address block is required. There are currently no 106 IPv6 unicast address blocks which are specifically nominated for the 107 purposes of implementing RTBH filters. 109 As [RFC5635] describes situations where more than one discard address 110 may be used for implementing multiple remote triggered black holes, a 111 single assigned prefix is not sufficient to cover all likely RTBH 112 filtering situations. Consequently, an address block is required in 113 preference to a single address. 115 3. Operational Implications 117 This assignment MAY be carried in a dynamic routing protocol within 118 an autonomous system. The assignment SHOULD NOT be announced to 119 third party autonomous systems and IPv6 traffic with an destination 120 address within this prefix SHOULD NOT be forwarded to third party 121 autonomous systems. 123 On networks which implement IPv6 remote triggered black holes, some 124 or all of this network block MAY be configured with a destination of 125 a discard or null interface on any or all IPv6 routers within the 126 autonomous system. 128 4. IANA Considerations 130 This document directs IANA to record the allocation of the IPv6 131 address prefix xxxx/64 as a discard-only prefix in the IPv6 Address 132 Space registry. No end party is to be assigned this prefix. The 133 prefix should be allocated from ::/3. 135 5. Security Considerations 137 As the prefix specified in this document should not normally be 138 transmitted or accepted over inter-domain BGP sessions, it is 139 appropriate to label the prefix as a Martian ([RFC3704]) for 140 inclusion in inter-domain BGP prefix filters. 142 6. References 144 6.1. Normative References 146 [RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole 147 Filtering with Unicast Reverse Path Forwarding (uRPF)", 148 RFC 5635, August 2009. 150 6.2. Informative References 152 [RFC1881] Internet Architecture Board and Internet Engineering 153 Steering Group, "IPv6 Address Allocation Management", 154 RFC 1881, December 1995. 156 [RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and 157 E. Lear, "Address Allocation for Private Internets", 158 BCP 5, RFC 1918, February 1996. 160 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 161 Requirement Levels", BCP 14, RFC 2119, March 1997. 163 [RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed 164 Networks", BCP 84, RFC 3704, March 2004. 166 [RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix 167 Reserved for Documentation", RFC 3849, July 2004. 169 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 170 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 171 May 2008. 173 [RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks 174 Reserved for Documentation", RFC 5737, January 2010. 176 Author's Address 178 Nick Hilliard 179 INEX 180 4027 Kingswood Road 181 Dublin 24 182 IE 184 Email: nick@inex.ie