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The finer points of ASP.NET authentication and some other things I learned today.

I’ve been involved with ASP.NET development pretty much since it was in beta and I thought that I really knew what was going on and could cut code pretty well.  I must have gotten rusty or something cuz I feel like I’ve learned a TON in the last month.  Usually the knowledge is aquired in spurts and usually on a day that tries a man’s (or woman’s) soul.  Today was one of those days.

Four things I learned today:

  1. If your web.config “authentication mode” (< authentication mode=”Forms” >) is set to “Forms“ and you want to access the user’s Windows username through NTLM, you are out of luck.  No amount of futzing with the IIS directory settings or “< identity impersonate=”true” / >“ will get you what you need.  You have to pick either mode=“Forms“ or mode=“Windows“.  What I wanted to do was to have my ASP.NET security first try to auth using the WindowsIdentity and if that isn’t available fall back to Forms authentication.  It looks like that automatic authorization without an IE login prompt won’t be possible. 
  2. ASP.NET runs as “NETWORK SERVICE“ on Windows 2003 and not ASPNET.  (read up)
  3. If the server that is running your ASP.NET application has a dot (aka “a period“, “.“) in the address, Internet Explorer won’t attempt to negotiate NTLM unless you’ve added that site to IE’s local intranet zone.  If there’s a dot, IE assumes that you’re hitting an internet site rather than an intranet set.  (read up)
  4. The Microsoft Patterns & Practices Enterprise Library Data Access Block (MPAPELDAB, for short) is trying to do something with the Event Log and/or the registry that it absolutely doesn’t have permissions to do.  Whenever there’s a data access problem (SqlException, etc), it tries to log the exception — fails — then everything comes crashing down like a load of extra-heavy, jet-powered bricks.  This blog post has been somewhat helpful….especially the comment that suggested going into the source code and editing out all the calls that try to write to the event log.  There’s also another FAQ.  And this post, too.  Alas, the problem is still not solved.  I’ve tried running ASP.NET as an administrator.  I’ve tried running “installutil“ over the MPAPELDAB dlls.  (See exception/stack trace below)

If anyone has any ideas on item #1 or item #4, please let me know.  Definitely let me know if you think I’m misunderstanding something about the security stuff. 

Major thanks to Mike Miller for helping me research and test out the Windows/Forms security stuff.  (He’s definitely one of the smartest guys I know.)



Here’s the exception:
[Win32Exception (0x80004005): Access is denied]

[InvalidOperationException: Cannot open log for source {0}. You may not have write access.]
   System.Diagnostics.EventLog.OpenForWrite() +363
   System.Diagnostics.EventLog.WriteEvent(Int32 eventID, Int16 category, EventLogEntryType type, String[] strings, Byte[] rawData) +280
   System.Diagnostics.EventLog.WriteEntry(String message, EventLogEntryType type, Int32 eventID, Int16 category, Byte[] rawData) +462
   System.Diagnostics.EventLog.WriteEntry(String message, EventLogEntryType type, Int32 eventID, Int16 category) +21
   System.Diagnostics.EventLog.WriteEntry(String message, EventLogEntryType type, Int32 eventID) +15
   System.Diagnostics.EventLog.WriteEntry(String message, EventLogEntryType type) +11
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.PerformanceCounterInstances.ReportCounterFailure(String message)

[InvalidOperationException: Exception in ReportCounterFailure(“Failed to create instances of performance counter ‘# of Command Failures/Sec’ – Couldn’t get process information from remote machine..”.  Here’s the debugging trace…Start;new EventLog(‘Application’, ‘.’, ‘Enterprise Library Instrumentation’);]
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.PerformanceCounterInstances.ReportCounterFailure(String message)
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.PerformanceCounterInstances..ctor(String categoryName, String counterName, Boolean createNewInstance)
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.InstrumentedEvent.AddPerformanceCounter(String category, String[] counterNames, Boolean createNewInstance)
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.InstrumentedEvent.Initialize(String counterCategory, String[] counterNames, Boolean createNewInstance, String eventLogSource, EventLogIdentifier[] eventIds)
   Microsoft.Practices.EnterpriseLibrary.Common.Instrumentation.InstrumentedEvent..ctor(String counterCategory, String[] counterNames, Boolean createNewInstance)
   Microsoft.Practices.EnterpriseLibrary.Data.Instrumentation.DataServiceEvent..ctor(String[] counterNames)
   Microsoft.Practices.EnterpriseLibrary.Data.Instrumentation.DataCommandFailedEvent..ctor(String[] counterNames)

[TypeInitializationException: The type initializer for “Microsoft.Practices.EnterpriseLibrary.Data.Instrumentation.DataCommandFailedEvent” threw an exception.]
   Com.Benday.Search.SearchDA.Execute(SearchDefinition search)
   Com.Benday.Search.SearchManager.Execute(SearchDefinition search)
   Timesheet.WebUI.Global.InitializeValues(String searchName, String storeAsKey) in c:inetpubwwwrootTimesheet.WebUIGlobal.asax.cs:50
   Timesheet.WebUI.Global.InitializeLookupValues() in c:inetpubwwwrootTimesheet.WebUIGlobal.asax.cs:30
   Timesheet.WebUI.Global.Application_BeginRequest(Object sender, EventArgs e) in c:inetpubwwwrootTimesheet.WebUIGlobal.asax.cs:79
   System.Web.SyncEventExecutionStep.System.Web.HttpApplication+IExecutionStep.Execute() +60
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +87



One response to “The finer points of ASP.NET authentication and some other things I learned today.”

  1. Andre Avatar

    To log to a custom event log you will find that if you are running visual studio in debug mode, the custom log is created and you can write to it successfully (provided your user access on the machine is admin). If however you now run the app under IIS and use the default credentials, the first time you run the site, the code runs under IIS credentials, the custom event branch is created, but you cannot write logs to it.
    You must set permissions on the event log entry in the registry and grant access for the user/account that your app is running under.
    I set all IIS / aspnet accounts full access to this key and have never had a problem since.

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