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Versions: 00

IPv6 Maintenance                                              L. Colitti
Internet-Draft                                                  E. Kline
Updates: 4862 (if approved)                                       Google
Intended status: Standards Track                           June 30, 2018
Expires: January 1, 2019


              Zero valid lifetimes on point-to-point links
               draft-zerorafolks-6man-ra-zero-lifetime-00

Abstract

   This document allows implementations to accept low or zero valid
   lifetimes in Router Advertisement Prefix Information Options in cases
   where it is known that there can only be one router on the link.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 1, 2019.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (https://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Cases when it is useful to reduce Valid Lifetime to zero  . .   2
   3.  Changes to RFC 4862 . . . . . . . . . . . . . . . . . . . . .   2
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   3
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   3
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   3

1.  Introduction

   Currently, Prefix Information Options in Router Advertisements cannot
   reduce the Valid Lifetime of an IPv6 address below 2 hours.  This is
   due to an explicit restriction in Section 5.5.3 of [RFC4862].  The
   reason is to avoid a denial-of-service attack whereby a malicious
   attacker can cause a node's addresses to expire prematurely by
   sending a Router Advertisement with a low Valid Lifetime.

1.1.  Requirements Language

   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 RFC 2119 [RFC2119].

2.  Cases when it is useful to reduce Valid Lifetime to zero

   In some cases, it is useful for the network to inform the host that a
   given prefix is no longer valid or will shortly no longer be valid.
   One example is if the host has moved beyond the mobility scope of the
   prefix and the network will no longer deliver packets for that prefix
   to the host.  The host can thus terminate any upper-layer connections
   using that prefix and notify applications that continued
   communication will require using a new source address.

   In order to ensure uninterrupted communications and no dispution to
   applications, this should be done only if the host already has other
   IPv6 addresses of equivalent scope and sufficient Valid Lifetime.

3.  Changes to RFC 4862

   The following clause is added between points 1 and 2 of clause e,
   Section 5.5.3 of [RFC4862]:





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   2. If the link-layer guarantees that there is only one node on the
      link from which the host can receive Router Advertiesements (e.g.,
      if the link is a point-to-point link, such as a PPP link or a 3GPP
      link as defined in [RFC6459]), and the link has another prefix of
      the same scope with sufficient Valid Lifetime, set the valid
      lifetime of the corresponding address to the advertised Valid
      Lifetime.

4.  IANA Considerations

   This memo includes no request to IANA.

5.  Security Considerations

   The denial-of-service attack that motivated this restriction cannot
   be mounted on a link where no other devices can send Router
   Advertisements to the host.

6.  References

6.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4862]  Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
              Address Autoconfiguration", RFC 4862,
              DOI 10.17487/RFC4862, September 2007,
              <https://www.rfc-editor.org/info/rfc4862>.

6.2.  Informative References

   [RFC6459]  Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
              T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
              Partnership Project (3GPP) Evolved Packet System (EPS)",
              RFC 6459, DOI 10.17487/RFC6459, January 2012,
              <https://www.rfc-editor.org/info/rfc6459>.

Authors' Addresses










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   Lorenzo Colitti
   Google
   Roppongi 6-10-1
   Minato, Tokyo  106-6126
   JP

   Email: lorenzo@google.com


   Erik Kline
   Google
   Roppongi 6-10-1
   Minato, Tokyo  106-6126
   JP

   Email: ek@google.com



































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