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NFS Version 2 and Version 3 Security Issues and the NFS Protocol's Use of RPCSEC_GSS and Kerberos V5
RFC 2623

Document type: RFC - Proposed Standard (June 1999)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

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IESG State: RFC 2623 (Proposed Standard)
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Network Working Group                                          M. Eisler
Request for Comments: 2623                        Sun Microsystems, Inc.
Category: Standards Track                                      June 1999

   NFS Version 2 and Version 3 Security Issues and the NFS Protocol's
                   Use of RPCSEC_GSS and Kerberos V5

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memorandum clarifies various security issues involving the NFS
   protocol (Version 2 and Version 3 only) and then describes how the
   Version 2 and Version 3 of the NFS protocol use the RPCSEC_GSS
   security flavor protocol and Kerberos V5.  This memorandum is
   provided so that people can write compatible implementations.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
   1.1.  Overview of RPC Security Architecture  . . . . . . . . . . . 3
   2.  Overview of NFS Security . . . . . . . . . . . . . . . . . . . 3
   2.1.  Port Monitoring  . . . . . . . . . . . . . . . . . . . . . . 3
   2.1.1.  MOUNT Protocol . . . . . . . . . . . . . . . . . . . . . . 4
   2.2.  RPC Security Flavors . . . . . . . . . . . . . . . . . . . . 4
   2.2.1.  AUTH_SYS . . . . . . . . . . . . . . . . . . . . . . . . . 5
   2.2.2.  AUTH_DH and AUTH_KERB4 . . . . . . . . . . . . . . . . . . 5
   2.2.3.  RPCSEC_GSS . . . . . . . . . . . . . . . . . . . . . . . . 5
   2.3.  Authentication for NFS Procedures  . . . . . . . . . . . . . 6
   2.3.1.  NULL Procedure . . . . . . . . . . . . . . . . . . . . . . 6
   2.3.2.  NFS Procedures Used at Mount Time  . . . . . . . . . . . . 6
   2.4.  Binding Security Flavors to Exports  . . . . . . . . . . . . 7
   2.5.  Anonymous Mapping  . . . . . . . . . . . . . . . . . . . . . 7
   2.6.  Host-based Access Control  . . . . . . . . . . . . . . . . . 8
   2.7.  Security Flavor Negotiation  . . . . . . . . . . . . . . . . 8
   2.8.  Registering Flavors  . . . . . . . . . . . . . . . . . . . . 9
   3.  The NFS Protocol's Use of RPCSEC_GSS . . . . . . . . . . . .   9

Eisler                      Standards Track                     [Page 1]
RFC 2623       NFS Security, RPCSEC_GSS, and Kerberos V5       June 1999

   3.1.  Server Principal . . . . . . . . . . . . . . . . . . . . .   9
   3.2.  Negotiation  . . . . . . . . . . . . . . . . . . . . . . .   9
   3.3.  Changing RPCSEC_GSS Parameters . . . . . . . . . . . . . .  10
   3.4.  Registering Pseudo Flavors and Mappings  . . . . . . . . .  11
   4.  The NFS Protocol over Kerberos V5  . . . . . . . . . . . . .  11
   4.1.  Issues with Kerberos V5 QOPs . . . . . . . . . . . . . . .  12
   4.2.  The NFS Protocol over Kerberos V5 Pseudo Flavor
         Registration Entry . . . . . . . . . . . . . . . . . . . .  13
   5.  Security Considerations  . . . . . . . . . . . . . . . . . .  14
   6.  IANA Considerations [RFC2434]  . . . . . . . . . . . . . . .  14
   6.1.  Pseudo Flavor Number . . . . . . . . . . . . . . . . . . .  14
   6.2.  String Name of Pseudo Flavor . . . . . . . . . . . . . . .  15
   6.2.1.  Name Space Size  . . . . . . . . . . . . . . . . . . . .  15
   6.2.2.  Delegation . . . . . . . . . . . . . . . . . . . . . . .  15
   6.2.3.  Outside Review . . . . . . . . . . . . . . . . . . . . .  15
   6.3.  GSS-API Mechanism OID  . . . . . . . . . . . . . . . . . .  15
   6.4.  GSS-API Mechanism Algorithm Values . . . . . . . . . . . .  15
   6.5.  RPCSEC_GSS Security Service  . . . . . . . . . . . . . . .  16
   References . . . . . . . . . . . . . . . . . . . . . . . . . . .  16
   Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . .  17
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . .  18
   Full Copyright Statement . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   The NFS protocol provides transparent remote access to shared file
   systems across networks. The NFS protocol is designed to be machine,
   operating system, network architecture, and security mechanism, and
   transport protocol independent. This independence is achieved through
   the use of ONC Remote Procedure Call (RPC) primitives built on top of
   an eXternal Data Representation (XDR).  NFS protocol Version 2 is
   specified in the Network File System Protocol Specification
   [RFC1094]. A description of the initial implementation can be found
   in [Sandberg]. NFS protocol Version 3 is specified in the NFS Version

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