DHCPV6 Working Group                                                    
Internet Draft                                                          
Intended status: Informational                                          
Expires: April 2009                                    October 25, 2008 
 
                                                                 Ruth Li 
                                                       Intel Corporation 
                                                         Vincent Zimmer 
                                                       Intel Corporation         
                                                               Dong Wei 
                                                        Hewlett-Packard 
                                                        Kathryn Hampton 
                                                        Hewlett-Packard 
                                                            Phil Doragh  
                                                        Hewlett-Packard 
                                                           Richard Chan 
                                                                   Dell 
                                                            Dave Thaler 
                                                              Microsoft 
                                                           Fiona Jensen
                                                                  Apple 
 
                                      
                        DHCPv6 Remote Boot Options 
            draft-zimmer-dhc-dhcpv6-remote-boot-options-00.txt 


Status of this Memo 

   By submitting this Internet-Draft, each author represents that       
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   becomes aware will be disclosed, in accordance with Section 6 of       
   BCP 79. 

   This document may not be modified, and derivative works of it may not 
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Internet-Draft        DHCPv6 Remote Boot Options           October 2008 
    

   The list of current Internet-Drafts can be accessed at 
   http://www.ietf.org/ietf/1id-abstracts.txt 

   The list of Internet-Draft Shadow Directories can be accessed at 
   http://www.ietf.org/shadow.html 

   This Internet-Draft will expire on April 27, 2009. 

Abstract 

   This document describes a means by which to support network boot of a 
   bare-metal platform utilizing a pre-boot execution environment, such 
   as the Unified Extensible Firmware Interface [UEFI22].   The problem 
   being addressed is that the PXE [PXE21] and UEFI Specifications 
   [UEFI22] only describe how to ascertain boot configuration options 
   using DHCPv4 [RFC2131], not for DHCPv6 [RFC3315].  Similarly, iSCSI 
   boot [RFC4173] does not specify how to discover boot device 
   information in an DHCPv6 environment.   This document will describe 
   how to ascertain this boot information in an IPv6 environment 
   utilizing options in the DHCPv6 hand-off [RFC3315]. 

Table of Contents 

    
   1. Introduction...................................................3 
   2. DHCPv6 Options ................................................4 
       ...................................Error! Bookmark not defined. 
      2.1. Root Path Option..........................................4 
      2.2. Server Address Option (former option 54 in DHCPv4)...Error! 
      Bookmark not defined. 
      2.3. Boot File Name Option (former option 67 in DHCPv4)........4 
      2.4. Boot File Size Option (former option 13 in DHCPv4)........5 
      2.5. Client System Architecture Type Option (former option 93).5 
      2.6. Client Network Interface Identifier Option ...............7 
      2.7. iSNS Option Definition (former option 83) [rfc4174].......7 
      2.8. SLP Directory Agent Option Definition (former option 
      78)[rfc2610]...................................................8 
      2.9. SLP Service Scope Option Definition (former option 79) 
      [rfc2610]......................................................8 
   3. Security Considerations........................................8 
   4. IANA Considerations............................................9 
   5. Acknowledgments................................................9 
   6. References....................................................10 
      6.1. Normative References.....................................10 
      6.2. Informative References...................................11 
    

 
 
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1. Introduction 

   Many hosts today have the ability to boot an Operating System image 
   (or "boot file") that is located on a server in the network.  To do 
   so, the host must begin with some functionality just sufficient to be 
   able to get on the network and retrieve the boot file.  As indicated 
   in Figure 1, it is desirable to obtain from DHCP the information 
   needed to locate the boot file, so that by the time the host is able 
   to communicate on the network, it can immediately begin downloading 
   the boot file. 
        
                                        +------+ 
                _______________________\| DHCP | 
               / 1 Get boot file info  /|Server| 
       +------+                         +------+ 
       | Host | 
       +------+                         +------+ 
               \_______________________\| File | 
                 2 Download boot file  /|Server| 
                                        +------+ 
        
       Figure 1: Network Boot Sequence 
        
   Two methods for downloading a boot file are specified today.   

   o iSCSI: [RFC2132] specifies a DHCPv4 option for retrieving boot file 
      information and [RFC4173] specifies how to download the boot 
      file. 

   o TFTP: [RFC2132] and [RFC4578] specify DHCPv4 options for retrieving 
      boot file information and [RFC1350] specifies how to download the 
      boot file. 

   The problem with both is that while the methods for downloading the 
   boot files can work over either IPv4 or IPv6, the boot file info can 
   only be obtained over DHCPv4.  As a result, they do not support a 
   network that only provides IPv6, nor do they support IPv6-only 
   devices.  To address this gap, this document specifies DHCPv6 
   options that provide parity with the DHCPv4 options. 

   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 [RFC2119]. 




 
 
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2. DHCPv6 Options  

2.1. The options in this list support both PXE and iSCSI.   The PXE-
   specific options include Client System Architecture type, Client 
   Network Interface Identifier Option, 
    
   The iSCSI-specific options include iSNS and SLP.The Root Path, Boot 
   File Name, and Boot File Size options are shared by both iSCSI and 
   PXE. 

2.2. Root Path Option 

   The Root Path option specifies the path-name that contains the 
   client's root disk. The path is formatted as a character string 
   consisting of characters from the NVT ASCII character set.  

   This option provides parity with the Root Path Option defined for 
   DHCPv4 in [RFC2132] section 3.19. 

        0                   1                   2                   3 
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |        OPTION_ROOT_PATH       |          option-len           | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       .                                                               . 
       .             root-disk-pathname (variable length)              . 
       .                                                               . 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        
       option-code         OPTION_ROOT_PATH (TBD1). 
        
       option-len           Length of Root Path Name in octets. 
        
       root-disk-pathname   An option field string as specified in 
                            [RFC4173] section 5. 
 

   
2.3. Boot File Name Option (former option 67 in DHCPv4) 

   This option specifies the path-name that contains the client's boot 
   file name. The path is formatted as a character string consisting of 
   characters from the NVT ASCII character set.  

         0                   1                   2                   3 
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 
 
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       |     OPTION_BOOT_FILE_NAME     |          option-len           | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       .                                                               . 
       .             Boot File Name (variable length)                  . 
       .                                                               . 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        
       option-code    OPTION_BOOT_FILE_NAME (TBD3). 
        
       option-len     Length in octets of the Boot File Name. 
        
       Boot File Name XXX to be filled in 
        
        
2.4. Boot File Size Option (former option 13 in DHCPv4) 

   This option specifies the length in 512-octet blocks of the default 
   boot image for the client.  The file length is specified as an 
   unsigned 32-bit integer. 

   This option goes beyond the Boot File Size Option defined for DHCPv4 
   in [RFC2132] section 3.15.   This is consistent with new pre-OS 
   technologies like UEFI [UEFI22] that use the PE/COFF specification 
   and allow for boot loaded images that are up to 4Gbytes in size. 

        0                   1                   2                   3 
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |     OPTION_BOOT_FILE_SIZE     |          option-len           | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |         File Size                                     | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        
       option-code    OPTION_BOOT_FILE_SIZE (TBD4). 
        
       option-len     4 
        
       File Size      The length in 512-octet blocks of the boot image for the 
                     client. 
        
2.5. Client System Architecture Type Option (former option 93)  

   This option provides parity with the Client System Architecture Type 
   Option defined for DHCPv4 in [RFC4578] section 2.1. 

   The format of the option is: 

 
 
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        0                   1                   2                   3 
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |    OPTION_CLIENT_ARCH_TYPE    |         option-len           | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       .                                                               . 
       .  Client System Architecture Type (variable length)            . 
       .                                                               . 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        
       option-code                       OPTION_CLIENT_ARCH_TYPE (TBD). 
        
       option-len                         XXX to be filled in  
        
       Client System Architecture Type    XXX to be filled in 
    

   Octet "n" gives the number of octets containing "architecture 
   types"(not including the code and len fields).  It MUST be an even 
   number equal to one.  Clients that support more than one architecture 
   type WILL describe the instruction that the UEFI or BIOS runs within 
   in their initial DHCP and PXE boot server packets.  Octets "n1" and 
   "n2" encode a 16-bit architecture type identifier that describes the 
   pre-boot runtime environment(s) of the client machine. 

    

        dd           Type   Architecture Name              
        ----   ----------------- 

        tbd##    Intel x86PC 

        tbd##    NEC/PC98 

        tbd##    EFI Itanium 

        tbd##    DEC Alpha 

        tbd##    Arc x86 

        tbd##    Intel Lean Client 

        tbd##   x86-64PC    

        tbd##    EFI BC    

        tbd##    EFI ARM 
 
 
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        tbd##    EFI x86-64 

        tbd##     EFI IA32 

2.6. Client Network Interface Identifier Option  

   The Client Network Interface Identifier option is sent by a DHCP 
   client to a DHCP server to provide information about its level of 
   Universal Network Device Interface (UNDI) support. 

   This option provides parity with the Client Network Interface 
   Identifier Option defined for DHCPv4 in [RFC4578] section 2.2. 

   The format of the option is: 

        0                   1                   2                   3 
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |           OPTION_NII          |          option-len           | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
       |     Type      |     Major     |      Minor      | 
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
        
       option-code    OPTION_NII (TBD). 
        
       option-len     3 
        
       Type          As specified in [RFC4578] section 2.2. 
        
       Major                           As specified in [RFC4578] section 2.2. 
        
       Minor                           As specified in [RFC4578] section 2.2. 
        
2.7. iSNS Option Definition (former option 83) [rfc4174] 

    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Code = OPTION ISNS tbd## |    Length     |          iSNS Functions       | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |           DD Access           |     Administrative FLAGS      | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                 iSNS Server Security Bitmap                   | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |      a1       |       a2      |       a3      |       a4      | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |      b1       |       b2      |       b3      |       b4      | 
 
 
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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |                            . . . .                            | 
   |                 Additional Secondary iSNS Servers             | 
   |                            . . . .                            | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 
    

2.8. SLP Directory Agent Option Definition (former option 78)[rfc2610] 

    

    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |   Code = OPTION SLP tbd## |    Length     |   Mandatory   |      a1       | 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |      a2       |       a3      |       a4      |      ... 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

2.9. SLP Service Scope Option Definition (former option 79) [rfc2610] 

   0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
   |      OPTION SLP SERVICE       |     Length    |   Mandatory   | <Scope List>... 
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

   option-code    OPTION_SLP_SERVICE (TBD). 

   option-len     See RFC2610 

3. Security Considerations 

   If an adversary manages to modify the response from a DHCP server or 
   insert its own response, a host could be led to contact a rogue file 
   server, resulting in an attacker being able to run arbitrary code on 
   the host.  Consequently, a practical way to verify loaded boot images 
 
 
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   is to make sure that each host verifies the boot file to be executed 
   using a mechanism of their choice. 

   In addition, some options contain information about a client's system 
   architecture and may be of use to potential attackers. 

   See the security considerations in [RFC3315], [RFC4173], and 
   [RFC4578] for more discussion.  This document introduces no new 
   concerns beyond the ones covered therein for IPv4. 

4. IANA Considerations 

   TBD 

5. Acknowledgments 

   The authors would like to thank Phil Doragh and Anil Kumar Reddy 
   Sirigiri from Hewlett-Packard.  We would also like to thank Joe 
   Calhoun and Jason Jin from Intel Corporation. We would also like to 
   thank Thomas Narten from IBM. 



























 
 
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6. References 

6.1. Normative References 

   [PECOFF]  Microsoft Portable Executable and Common Object File 
             Format, Revision 8.1, March 27, 2008 
             http://www.microsoft.com/whdc/system/platform/firmware/PECO
             FF.mspx 

   [PXE21]   Henry, M. and M. Johnston, "Preboot Execution Environment 
             (PXE) Specification", September 1999,        
             http://www.pix.net/software/pxeboot/archive/pxespec.pdf 

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

   [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, 
             March, 1997. 

   [RFC2610] C. Perkins, E. Guttman, "DHCP Options for Service Location 
             Protocol", RFC2610, June 1999. 

   [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and 
             Carney, M., "Dynamic Host Configuration Protocol for IPv6 
             (DHCPv6)", RFC 3315, July 2003. 

   [RFC4172] Monia, C., Tseng, J., and K. Gibbons, "The IPv4 Dynamic
             Host Configuration Protocol (DHCP) Option for the                
             Internet Storage Name Service", RFC 4174, September 2005. 

   [RFC4173] Sarkar, P., Missimer, D. and Sapuntzakis, C., 
             "Bootstrapping Clients using the Internet Small Computer 
             System Interface (iSCSI) Protocol", RFC 4173, September 
             2005 

   [RFC4578] Johnston, M. and Venaas, S. "Dynamic Host Configuration 
             Protocol (DHCP) Options for the Intel Preboot eXecution 
             Environment (PXE)", RFC 4578, November 2006. 

   [RFC2610] C. Perkins, E. Guttman, "DHCP Options for Service 
             Location Protocol", RFC2610, June 1999. 

   [UEFI22]  Unified Extensible Firmware Interface Specification, 
             Version 2.2, September 2008, http://www.uefi.org 

    

 
 
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6.2. Informative References 

Author's Addresses 

   Vincent Zimmer 
   Intel 
   DP2-420 
   2800 Center Drive 
   DuPont, WA 98327 
       
   Phone: 253-371-5667 
   Email: vincent.zimmer@intel.com 
    

   Dave Thaler 
   Microsoft 
   One Microsoft Way 
   Redmond, WA 98052 
       
   Phone: +1 425 703-8835 
   Email: dthaler@microsoft.com 
    

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   this document or the extent to which any license under such rights 
 
 
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