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BEHAVE WG                                                        F. Gont
Internet-Draft                                                   UTN/FRH
Intended status: BCP                                    October 27, 2008
Expires: April 30, 2009


  Security implications arising from the non-modification of protocol
          header fields by Network Address Translators (NATs)
                 draft-gont-behave-nat-security-00.txt

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Abstract

   This document analizes the security implications arising from the
   non-modification of some TCP and IP protocol header fields by Network
   Address Translators (NATs).









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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Internet Protocol version 4 (IPv4) header fields  . . . . . . . 3
     2.1.  Version . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.2.  IHL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.3.  Type of Service . . . . . . . . . . . . . . . . . . . . . . 3
     2.4.  Total Length  . . . . . . . . . . . . . . . . . . . . . . . 3
     2.5.  Identification  . . . . . . . . . . . . . . . . . . . . . . 3
     2.6.  Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.7.  Fragment Offset . . . . . . . . . . . . . . . . . . . . . . 3
     2.8.  Time to Live  . . . . . . . . . . . . . . . . . . . . . . . 3
     2.9.  Protocol  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.10. Header Checksum . . . . . . . . . . . . . . . . . . . . . . 3
     2.11. Source Address  . . . . . . . . . . . . . . . . . . . . . . 3
     2.12. Destination Address . . . . . . . . . . . . . . . . . . . . 3
     2.13. Options . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.14. Padding . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Transmission Control Protocol (TCP) header fields . . . . . . . 3
     3.1.  Source Port . . . . . . . . . . . . . . . . . . . . . . . . 3
     3.2.  Destination Port  . . . . . . . . . . . . . . . . . . . . . 4
     3.3.  Sequence Number . . . . . . . . . . . . . . . . . . . . . . 4
     3.4.  Acknowledgment Number . . . . . . . . . . . . . . . . . . . 4
     3.5.  Data Offset . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.6.  Reserved  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.7.  Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.8.  Window  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.9.  Checksum  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.10. Urgent Pointer  . . . . . . . . . . . . . . . . . . . . . . 4
     3.11. Options . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.12. Padding . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 4
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5
   Intellectual Property and Copyright Statements  . . . . . . . . . . 6












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1.  Introduction

   This document analizes the security implications arising from the
   non-modification of some TCP and IP protocol header fields by Network
   Address Translators (NATs).

   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.  Internet Protocol version 4 (IPv4) header fields

2.1.  Version

2.2.  IHL

2.3.  Type of Service

2.4.  Total Length

2.5.  Identification

2.6.  Flags

2.7.  Fragment Offset

2.8.  Time to Live

2.9.  Protocol

2.10.  Header Checksum

2.11.  Source Address

2.12.  Destination Address

2.13.  Options

2.14.  Padding


3.  Transmission Control Protocol (TCP) header fields

3.1.  Source Port






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3.2.  Destination Port

3.3.  Sequence Number

3.4.  Acknowledgment Number

3.5.  Data Offset

3.6.  Reserved

3.7.  Flags

3.8.  Window

3.9.  Checksum

3.10.  Urgent Pointer

3.11.  Options

3.12.  Padding


4.  Security Considerations


5.  IANA Considerations

   This document has no actions for IANA.


6.  Acknowledgements


7.  References

7.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              September 1981.

   [RFC0793]  Postel, J., "Transmission Control Protocol", STD 7,
              RFC 793, September 1981.

   [RFC1122]  Braden, R., "Requirements for Internet Hosts -
              Communication Layers", STD 3, RFC 1122, October 1989.

   [RFC1323]  Jacobson, V., Braden, B., and D. Borman, "TCP Extensions



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              for High Performance", RFC 1323, May 1992.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

7.2.  Informative References

   [RFC2663]  Srisuresh, P. and M. Holdrege, "IP Network Address
              Translator (NAT) Terminology and Considerations",
              RFC 2663, August 1999.


Author's Address

   Fernando Gont
   Universidad Tecnologica Nacional / Facultad Regional Haedo
   Evaristo Carriego 2644
   Haedo, Provincia de Buenos Aires  1706
   Argentina

   Phone: +54 11 4650 8472
   Email: fernando@gont.com.ar
   URI:   http://www.gont.com.ar




























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