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Login failed for user ''(null)'' in linked server

  • March 2, 2005 at 3:55 pm

    #102413

    I have server A and server B.

    Server A is on a Win XP machine, server 2 in WIN 2000 Server. My windows login is sysadmin on both SQL server A and B. The same win login is in local administrators group on both machines.

    Both SQL servers use mixed authentication mode.

    The service account on SQL Server A is my Windows account. On SQL Server B is another domain\user account. This windows account (domain\user) is a windows user on machine A and also a sysadmin on SQL Server on machine A.

    I linked server B from server A using EM, server type='SQL Server'. No local login defined under Security tab, just checked 'Be made using login's current security account'. I can access server B from EM and Query analyzer if I log with my Windows login. So server B trusts my credentials when they come from server A.

    I link the server A from server B using the same settings: No local login defined under Security tab, just checked 'Be made using login's current security account'. When I try to access from EM the server B I get "Login failed for user '(null)', Reason: not associated with a trusted connection.

    I get the same message if I connect to server B with my win account in QA and I try to access server A. So it seems that:

    a) my credentials are not good enough when they come from server B on server A;

    or

    b) the attempted connection doesn't use my credentials, but in this case which is the security context?

    Is killing me because it looks pretty symmetrical but it doesn't work that way.

    I tried to find some answers in previous postings on this forum, but with no luck.

    I will be really happy if somebody will give me any idea.

     

    Gabriela

  • March 2, 2005 at 4:13 pm

    #545063

    Had similar experiences.

    Try IP address of server A instead of name.

  • March 3, 2005 at 7:21 am

    #545204

    This sounds like a double hop issue. You're connecting using Windows authentication when coming from QA, right?

    Are you still an NT 4 domain or an Active Directory domain?

    K. Brian Kelley
    @kbriankelley

  • March 3, 2005 at 7:35 am

    #545213

    check this articles. you need to set up security account delegation

    http://www.sql-server-performance.com/tb_kerberos_protocol_transition.asp

    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/adminsql/ad_1_server_24tv.asp

    http://msdn.microsoft.com/library/default.asp?url=/library/en-us/adminsql/ad_security_2gmm.asp

     

  • March 3, 2005 at 7:45 am

    #545218

    This works if they are on an AD domain. There isn't delegation on NT 4. Hence the reason I asked the question.

    K. Brian Kelley
    @kbriankelley

  • March 3, 2005 at 10:33 am

    #545282

    You are right brian. Need to verify whether it is NT or Active Directory.

  • March 3, 2005 at 12:46 pm

    #545319

    it may be the dcom config of the xp machine.

    at the run prompt type "dcomcnfg"

    go to component services, then to my computer

    right click my computer and choose properties

    click the MSDTC tab

    click security configuration

    check network DTC access

    check allow remote clients and allow inbound

    make sure the DTC Logon Account is "NT AUTHORITY\NetworkService"

    click OK

    restart the MSDTC service

    This will allow the local DTC service on the XP machine to interact with remote distributed transactions on the network. HTH

    Cody Pack
    MCSE Windows 2000
    MCDBA SQL Server 2000

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