Network Address Translation Support for QUIC
draft-duke-quic-natsupp-00

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Last updated 2019-11-25
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QUIC                                                             M. Duke
Internet-Draft                                         F5 Networks, Inc.
Intended status: Informational                         November 25, 2019
Expires: May 28, 2020

              Network Address Translation Support for QUIC
                       draft-duke-quic-natsupp-00

Abstract

   Network Address Translators (NATs) are widely deployed to share
   scarce public IPv4 addresses among mutiple end hosts.  They overwrite
   IP addresses and ports in IP packets to do so.  QUIC is a protocol on
   top of UDP that provides transport-like services.  QUIC is better-
   behaved in the presence of NATs than older protocols, and existing
   UDP NATs should operate without incident if unmodified.  QUIC offers
   additional features that may tempt NAT implementers as potential
   optimizations.  However, in practice, leveraging these features will
   lead to new connection failure modes and security vulnerabilities.

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
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   This Internet-Draft will expire on May 28, 2020.

Copyright Notice

   Copyright (c) 2019 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
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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Internet-Draft              QUIC NAT Support               November 2019

   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  QUIC and NAT Rebinding  . . . . . . . . . . . . . . . . . . .   3
   4.  The Lure of the Connection ID . . . . . . . . . . . . . . . .   3
     4.1.  Resource Conservation . . . . . . . . . . . . . . . . . .   3
     4.2.  "Helping" with routing infrastructure issues  . . . . . .   3
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   4
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Network Address Translators (NATs) are a widely deployed means of
   multiplexing multiple private IP addresses over scarce IPv4 public
   address space by replacing those addresses and using ports to
   distinguish those connections.  The new address can also guarantee
   that packets move through a proxy throughout the life of a
   connection, so that the connection can continue with the required
   state at that proxy.

   QUIC [QUIC-TRANSPORT] is a protocol, operating over UDP, that
   provides many transport-like services to the application layer.
   Among these services is the mapping of multiple endpoint IP addresses
   to a single connection through use of a Connection ID (CID).
   Connection IDs are opaque byte fields that are expressed consistently
   across all QUIC versions [QUIC-INVARIANTS].  This feature may appear
   to present opportunities to optimize NAT port usage and simplify the
   work of the QUIC server.  In fact, NAT behavior that relies on CID
   may instead cause connection failure when endpoints change Connection
   ID, and disable important protocol security features.

   The remainder of this document explains how QUIC supports NATs better
   than other connection-oriented protocols, why NAT use of Connection
   ID might appear attractive, and how NAT use of CID can create serious
   problems for the endpoints.  The conclusion of this document is that
   NATs should retain their existing 4-tuple-based operation and refrain
   from parsing or otherwise using QUIC connection IDs.

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