[cifs-protocol] [REG:110100459556182] [MS-BKRP] The behavior for BachuprKey RPC call issed against a RODC

Matthieu Patou mat at samba.org
Fri Oct 8 13:33:48 MDT 2010

  Hello Bryan,

Thanks for the explanation that's more clearer right now like this.

Please let me know also about the pb with backupkey when samba is the os 
that generated the keys.


  On 07/10/2010 20:45, Bryan Burgin wrote:
> Matthieu,
> This regards the issue you raised at the IO Lab regarding what error code a MS-BKRP server implementation should return if called on a RODC.  You observed that the Microsoft MS-BKRP implementation in this scenario returns INVALID_PARAMETER.
> I believe the documentation supports that behavior.  [MS-BKRP] 1.3.1 specifies that all writable DCs participate in MS-BKRP while no other machines (including RODCs) "support BackupKey Remote Protocol server functionality."  At [MS-BKRP] BackuprKey (Opnum 0) ... Return Values, it says "[...]If the server does not support the pguidActionAgent value in the client request, the server MUST return ERROR_INVALID_PARAMETER (0x57) [...]".  Since RODCs MUST NOT "support BackupKey Remote Protocol server functionality". Returning ERROR_INVALID_PARAMETER is appropriate.
> A client should not be talking a protocol to a server unless it knows that the server is a compliant implementation. As we have noted in 1.3.1, RODCs are not compliant implementations of MS-BKRP.  In a Microsoft Active Directory domain, the DC Locator functionality can be used to locate a writable DC. Therefore, MS-BKRP clients should use this to locate a compliant server. In non-Microsoft implementations, the client is expected to have some other method of locating a compliant server, as noted in Section 1.5:  "The client of the Backup Key RPC interface must implement a mechanism to determine a server to connect to, and any additional configuration required by this mechanism must be carried out."
> I will close this issue as resolved.  But, if any additional follow-up is necessary, please contact me.
> I have several other active MS-BKRP issues I'm working on for you, which I'll summarize in a separate e-mail.
> Bryan

Matthieu Patou
Samba Team        http://samba.org

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