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Certain windows user is blocked! RRS feed

  • Question

  • This problem is occurring in some clients computers with our software. The software connects to another computer using WCF to other computers. The problem is that sometimes certain windows user is prevented from connecting to windows! When we change the windows user it will work! Then after a while that certain windows user does not work! The software connects to SQL Server using our WCF windows service. The weird thing is that when we change the database name using connection string it then works again. Database does not understand the user because all users are connected to the sql server with one user. But when we change the name of the database with management studio it does not work.

    We have stopped the firewall and stopped all the antivirus as well when we test but the problem persist. 

        

    Mike

    Monday, August 26, 2019 8:49 AM

All replies

  • Hi,

    I do not understand your application scenario. Your client computer needs to provide window credentials when calling the WCF service, and you use a fixed account on the server to connect to the remote database?  Is the issue that some certain windows user could not call the service properly?

    Best Regards

    Abraham

    Monday, August 26, 2019 9:59 AM
    Moderator
  • Connecting to the server computer uses ip:port and it is fine for all users and 'sa' user fopr sql server. But ewr do not know if it is the server that block that certain windows user or the sql server. We do not use windows authentication to connect hence no need for any credential. We easily connect to the server using ip:port/WCFChannel. This software has this for 10 years! But recently this happens and we do not have any clue. 
    Please note that we connect to server and the using that we connect to sql server.

    Is the issue that some certain windows user could not call the service properly? Yes this is true, but for first 1 week it is ok but all the sudden it happens only for a certain database in SQL Server! This means the other databases work! 


    Mike


    • Edited by Mike9000 Monday, August 26, 2019 1:22 PM
    Monday, August 26, 2019 12:59 PM
  • Hi,

    Where is the windows user? is it on the client-side? if indeed, which managed environment the server used for hosting the WCF service? IIS generally provide the application pool identity to run the service, thereby the issue should have nothing with the client's windows user that connect the server computer.

    Best Regards

    Abraham

    Tuesday, August 27, 2019 2:36 AM
    Moderator
  • Thank you for your prompt response. 

    Windows user is on the client. Our application server (ABServer to be called) is managed by a windows service in the server. The user has nothing to do with server and sql server as well. ABServer uses one user name for all connections to sql server and does not have to do anything with that user name. Connecting to the server is also through ip:port which has nothing to do with that. But it is that user on that computer that blocks the connection to the ABServer and then sql server! 

    When we create a new windows user, that user can connect to ABServer for sometimes and then it will be blocked. Please note the other users in other computers can connect to the server easily. This problem is now happening in 10 of our clients. Please notice also that when they change the database for that user it works!


    Mike

    Tuesday, August 27, 2019 7:53 AM
  • Hi,

    Is it possible that SQL server limits the number of concurrent connections? Causing client connection problems?

    Best Regards

    Abraham

    Tuesday, August 27, 2019 8:55 AM
    Moderator
  • I guess it it possible if they are using SQL Express! Since they are using SQL Express it may happen! But the question is why SQL Sever does not create any exception? The connection dialog freezes forever! But some of the clients do not have many users. so, I doubt it is because of that!

    Today I did something and they say it worked and if it works for other clients it mean it is fixed! I only encrypted userId, serverId and instance when I sent to ABCServer! Then at ABCServer it decrypted the user name! Password was encrypted before. If this is the case it means something was blocking the user in the client!


    Mike

    Tuesday, August 27, 2019 8:15 PM
  • Hi,

    What is the details about “Block”, how do you get that?

    In addition to the maximum concurrent connections that SQL server limits, the WCF server-side also is able to limit the number of concurrent connections, which means that the number of clients connecting at the same time is limited. Consider the WCF server definition below.

        

    <behaviors>
    
          <serviceBehaviors>
    
            <behavior name="ServiceBehavior">
    
              <serviceMetadata httpGetEnabled="true"/>
    
              <serviceDebug includeExceptionDetailInFaults="true"/>
    
              <serviceThrottling maxConcurrentCalls="1000"
    
                                    maxConcurrentInstances ="250"
    
                                    maxConcurrentSessions ="500"/>
    
            </behavior>
    
          </serviceBehaviors>
    
    </behaviors>
    
    

    https://www.codeproject.com/Articles/89858/WCF-Concurrency-Single-Multiple-and-Reentrant-and

    Anyway, welcome to share your solution to this issue regardless of the method you use, this will help others who ran into a similar problem.

    Feel free to let me know if there is anything I can help with.

    Best Regards

    Abraham


    Thursday, August 29, 2019 9:53 AM
    Moderator