DOCUMENT:Q122702 08-AUG-2001 [winnt] TITLE :Using the System Account as a Service in Windows NT 3.5 PRODUCT :Microsoft Windows NT PROD/VER: OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0 - Microsoft Windows NT Server versions 3.5, 3.51, 4.0 ------------------------------------------------------------------------------- SUMMARY ======= Windows NT allows a service to use either a system account or a user- specific account to access resources on a local or remote computer. After you upgrade a computer from Windows NT version 3.1 to Windows NT version 3.5, 3.51 or 4.0, the service may fail or an "Access Denied" error message may appear if the service is using the system account. MORE INFORMATION ================ If a service is using the system account to access resources, the service logs on with a set of "null credentials." In Windows NT version 3.1, system accounts had general access to shares. However, in Windows NT version 3.5, 3.51 and 4.0, there is a Server service registry parameter that enables tighter security by allowing you to specify by name which shares (and pipes) the system account can access. The Registry parameter is "RestrictNullSessAccess" (without the quotation marks) and it defaults to TRUE. Two other parameters, "NullSessionPipes" and "NullSessionShares" (without quotation marks) allow you to specify lists of share names and pipe names that can be accessed by the system account. In other words, by default, the only shares your client's service can access are those listed in the "NullSessionShares" parameter value. To change this behavior, the administrator can either set "RestrictNullSessAccess" to FALSE, or add the names of shares the service needs access to in the "NullSessionShares" parameter value on servers where those shares exist. To disable the "RestrictNullSessAccess" entry, modify the Registry by doing the following: WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk. 1. Start the Registry Editor (REGEDT32.EXE) 2. From the \HKEY_LOCAL_MACHINE subkey, go to the key: \SYSTEM \CurrentControlSet \Services \LanmanServer \Parameters 3. From the Edit menu, select Add Value. 4. For the Value Name, enter RestrictNullSessAccess. For Data Type, select REG_DWORD and choose OK. In DWORD Editor, enter 0 for Data. Choose OK. 5. Exit Registry Editor and restart Windows NT. ====================================================================== Keywords : Technology : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT350search kbWinNT400search kbWinNTW350 kbWinNTW350search kbWinNTW351search kbWinNTW351 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS350 kbWinNTS351search kbWinNTS350search ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2001.