draft-ietf-secsh-dns-05.txt

bind 9.3结合mysql数据库

   DNS zone administrator (in transferring the fingerprint), detailed
   aspects of how verification is done in the SSH implementation, and in
   the client's diligence in accessing the DNS in a secure manner.

   One such aspect is in which order fingerprints are looked up (e.g.
   first checking local file and then SSHFP).  We note that in addition
   to protecting the first-time transfer of host keys, SSHFP can
   optionally be used for stronger host key protection.

      If SSHFP is checked first, new SSH host keys may be distributed by
      replacing the corresponding SSHFP in DNS.

      If SSH host key verification can be configured to require SSHFP,
      SSH host key revocation can be implemented by removing the
      corresponding SSHFP from DNS.

   As stated in Section 2.2, we recommend that SSH implementors provide
   a policy mechanism to control the order of methods used for host key
   verification. One specific scenario for having a configurable policy
   is where clients use unqualified host names to connect to servers. In
   this case, we recommend that SSH implementations check the host key



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   against a local database before verifying the key via the fingerprint
   returned from DNS. This would help prevent an attacker from injecting
   a DNS search path into the local resolver and forcing the client to
   connect to a different host.

   A different approach to solve the DNS search path issue would be for
   clients to use a trusted DNS search path, i.e., one not acquired
   through DHCP or other autoconfiguration mechanisms. Since there is no
   way with current DNS lookup APIs to tell whether a search path is
   from a trusted source, the entire client system would need to be
   configured with this trusted DNS search path.

   Another dependency is on the implementation of DNSSEC itself.  As
   stated in Section 2.4, we mandate the use of secure methods for
   lookup and that SSHFP RRs are authenticated by trusted SIG RRs.  This
   is especially important if SSHFP is to be used as a basis for host
   key rollover and/or revocation, as described above.

   Since DNSSEC only protects the integrity of the host key fingerprint
   after it is signed by the DNS zone administrator, the fingerprint
   must be transferred securely from the SSH host administrator to the
   DNS zone administrator.  This could be done manually between the
   administrators or automatically using secure DNS dynamic update [11]
   between the SSH server and the nameserver.  We note that this is no
   different from other key enrollment situations, e.g. a client sending
   a certificate request to a certificate authority for signing.

5. IANA Considerations

   IANA needs to allocate a RR type code for SSHFP from the standard RR
   type space (type 44 requested).

   IANA needs to open a new registry for the SSHFP RR type for public
   key algorithms.  Defined types are:

         0 is reserved
         1 is RSA
         2 is DSA

    Adding new reservations requires IETF consensus [4].

   IANA needs to open a new registry for the SSHFP RR type for
   fingerprint types.  Defined types are:

         0 is reserved
         1 is SHA-1

    Adding new reservations requires IETF consensus [4].



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Normative References

   [1]  Mockapetris, P., "Domain names - concepts and facilities", STD
        13, RFC 1034, November 1987.

   [2]  Mockapetris, P., "Domain names - implementation and
        specification", STD 13, RFC 1035, November 1987.

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

   [4]  Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA
        Considerations Section in RFCs", BCP 26, RFC 2434, October 1998.

   [5]  Eastlake, D., "Domain Name System Security Extensions", RFC
        2535, March 1999.

   [6]  Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S.
        Lehtinen, "SSH Protocol Architecture",
        draft-ietf-secsh-architecture-14 (work in progress), July 2003.

   [7]  Ylonen, T., Kivinen, T., Saarinen, M., Rinne, T. and S.
        Lehtinen, "SSH Transport Layer Protocol",
        draft-ietf-secsh-transport-16 (work in progress), July 2003.

Informational References

   [8]   Thayer, R., Doraswamy, N. and R. Glenn, "IP Security Document
         Roadmap", RFC 2411, November 1998.

   [9]   Vixie, P., Gudmundsson, O., Eastlake, D. and B. Wellington,
         "Secret Key Transaction Authentication for DNS (TSIG)", RFC
         2845, May 2000.

   [10]  Eastlake, D., "DNS Request and Transaction Signatures (
         SIG(0)s)", RFC 2931, September 2000.

   [11]  Wellington, B., "Secure Domain Name System (DNS) Dynamic
         Update", RFC 3007, November 2000.












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Authors' Addresses

   Jakob Schlyter
   OpenSSH
   812 23rd Avenue SE
   Calgary, Alberta  T2G 1N8
   Canada

   EMail: [e-mail]
   URI:   http://www.openssh.com/


   Wesley Griffin
   SPARTA
   7075 Samuel Morse Drive
   Columbia, MD  21046
   USA

   EMail: [e-mail]
   URI:   http://www.sparta.com/

Appendix A. Acknowledgements

   The authors gratefully acknowledge, in no particular order, the
   contributions of the following persons:

      Martin Fredriksson

      Olafur Gudmundsson

      Edward Lewis

      Bill Sommerfeld


















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