Anonymous level security token - Windows Server

During a software installation if setup fails and shows similar logs like below then it is related with Windows Component system.

MSI (c) (48:B0) SOFTWARE RESTRICTION POLICY: Verifying package --> '...\NC.x64.msi' against software restriction policy 

MSI (c) (48:B0)  Note: 1: 2262 2: DigitalSignature 3: -2147287038  

MSI (c) (48:B0)  SOFTWARE RESTRICTION POLICY: ...\NC.x64.msi is not digitally signed 

MSI (c) (48:B0) SOFTWARE RESTRICTION POLICY: ...\NC.x64.msi is permitted to run at the 'unrestricted' authorization level.

The software which I tried to install had prerequisites (Dotnet Framework 3.5 etc).
After error, I tried to install Dotnet 3.5 manually from "Server Manager" by clicking "Add roles and features" link. But it failed and showed error below:

Anonymous level security token

To solve I followed these steps:

1. Click Start > Run, type dcomcnfg.exe
2. Click OK if you see the UAC warning
3. Go to Component Services> Computers in the tree
4. Right click My Computer > select Properties.
5. Click Default Properties tab
6. Select Connect in the Default Authentication Level list 
7. Select Identify in the Default Impersonation Level list
8. Click OK, and confirm the selection
9. Close Component Services console

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Python code to exe (Windows)

PyInstaller helps you convert your python code to executable software package.

Our test environment: Windows 7, Python 3.6

Create your python code file (hello.py)

print("Hello World!")

Download PyInstaller via pip

pip install pyinstaller

Run PyInstaller with python code file parameter on console

"C:\Program Files\Python36\Scripts\pyinstaller.exe" hello.py

You will see some commands on the screen. A few seconds later it will finish building. Build time is dependent your code (referenced packages).

Check dist folder for distribution copy of your application (hello.exe)

Size of the folder for hello.py is around 11mb.

I tried also py file with reference of cv2 library. Build time is around 30seconds and folder size becomes 157mb.

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How to free up disk space on Windows

If you have a small disk size and have to open free space frequently on Windows then this post is for you.

You deleted some files, emptied recycle bin, moved some files to another drive but still you need free space. Because Windows is living, getting updates, creating cache files also you install new applications. First we will give a chance to Windows for disk cleanup then we will try to find more files to delete.

1. Windows Cleanup

Right click to C:\ drive and select Properties. You will see Disk Cleanup  button in General tab.
 


This will give you some space. You can see many unnecessary items here like temporary files, Windows Update files etc. If you are not happy with that space then continue.


2. Find more files

WinDirStat is a utility that shows size statistics about your files and folders in your drive. With this tool you can see which folders and files have the most size. I love this tool because its graphical interface shows file types in colors, sizes as blocks. You can select a big block and see which file it is.  For example I ordered folders and files by size. In my computer the Installer folder is very huge. It occupies nearly 30% size in Windows folder. When you explore in Installer folder you will see many setup and patch files. We can't know which file is used by the system or necessary by looking their names. File names are like "1a88ba.msp".



3. Analyze Installer folder

You shouldn't delete files from Installer folder because uninstall process will search for installation files in this folder. Alternatively you can backup this folder content in somewhere else or zip the folder. This may also can create workload because you need to put right file again to start uninstall process.

Patch Cleaner is an application that searchs Installer folder for unnecesarry files -namely orphaned files. 



You can see necessary files with their explanation.
 



Orphaned file list shows files that are not connected to any application.





You can move orphaned files to another drive like a USB disk by pressing Move button.


4. Continue to investigate files with WinDirStat

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Install opencv package in Python

Opencv is very popular library on all platforms. This article explains how to install opencv package for Python. This will give you a general idea about installing any library in Python environment.

In code samples you will see cv2 library is imported.

import cv2

If you run sample code without installing opencv you will get following error.

Traceback (most recent call last):
  File "pythonface.py", line 2, in
    import cv2
ImportError: No module named cv2

Installing python package from online repository is very easy in python. You can search for a package in PyPI (Python Package Index) interface.

Type opencv to search box in pypi webpage (https://pypi.python.org/pypi)

This will give you a long list which contains your keyword.

List cropped for blog post.

Finding right package may be hard in this list. You can find package names from original sources of specific libraries.

If you click "opencv-python 3.3.0.10" from the list (https://pypi.python.org/pypi/opencv-python/3.3.0.10) you will see installation and usage guide.

On docs.opencv.org you can see library name as opencv-python:

OpenCV-Python is the Python API for OpenCV, combining the best qualities of the OpenCV C++ API and the Python language.

Use following command to install opencv library to your computer from PyPI.

pip install opencv-python

Now you are ready to use opencv functions.

If you can't find opencv-python package in your installation you can download source codes and run commands according to your environment. This link will give you an idea about sequence of this work.

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Split video into frames

You can split video into frames with AForge libraries.

Add reference following libraries:

• AForge.Video
• AForge.Video.FFMPEG

// create instance of video reader
VideoFileReader reader = new VideoFileReader();
// open video file
reader.Open("C:\\test.mp4");
long framecount = reader.FrameCount; 

// read video frames 
for (int i = 0; i < framecount; i++)
{
 Bitmap videoFrame = reader.ReadVideoFrame();
 
 videoFrame.Save(Environment.CurrentDirectory + "\\" + i + ".bmp");

 // dispose the frame when it is no longer required
 videoFrame.Dispose();
}
reader.Close();

Quickwatch reader object

ReadVideoFrame: Read next video frame of the currently opened video file.

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How to send an object and a parameter to an asp.net web api

In this sample we will post an object and a string parameter with ajax from client. Asp.net side will recognize data as form data. We will convert (deserialize) coming object data into corresponding class.

• Server side: Webapi function

[HttpPost]

public string WebapiPost()

{

    var httpRequest = HttpContext.Current.Request;

    string name = httpRequest.Form["name"];

    string jsonObj = httpRequest.Form["obj"];

    JavaScriptSerializer jsonSerializer = new JavaScriptSerializer();

    MyObject obj = jsonSerializer.Deserialize<MyObject>(jsonObj);

    return obj.Key;

}

public class MyObject

{

    public int ID { get; set; }

    public string Key { get; set; }

}

• Client side: Post function 

function PostDataSample(url, data) {

    $.ajax({

        type: "POST",

        url: url,

        data: data,

        dataType: 'html',

        success: function (response) {

            console.log("PostData::success");

            callback(response);

        },

        failure: function (response) {

            console.log("PostData::failure");

            callback(response);

        }

    });

}

Note that "dataType" is "html"

• Client side: Call post function

var name = "Oktay";

var myObject = {};

myObject.ID = 1;

myObject.Key = "key1";

PostDataSample("/api/postMyobject/WebapiPost", "obj=" + JSON.stringify(myObject) + "&name=" + name, "html");

Note that we used object as JSON.stringify. You can add more parameters.

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HTML5 Webcam Case: Add server certificate to trusted in Chrome

In the previous post we created a self-signed certificate on the server. But Google Chrome still shows the certificate as not trusted on the client side.

All steps will be applied at client side with Google Chrome browser.

Click the lock icon near the https url. In popup it says "Server's certificate is not trusted".

Click "Certificate Information" link and the go to "Details" tab.

 Click "Copy to File...". You will see Certificate Export Wizard window.

 Click Next and enter a path for the file including filename.

 Complete the wizard and you will see "The export was successful" message.

Go to Chrome settings and find "Manage certificates" button.

 Go to "Trusted Root Certification Authorities" tab and click "Import..." button. We will import the certificate which we exported in the previous steps.

 You will see "Certificate Import Wizard" window. Click Next and select certificate file you exported.

 Here we are adding the certificate to the "Trusted Root Certification Authorities". Complete the wizard.

You will see "The import was successful" message. Now you will not see error lock icon near the https url in Chrome. Also related with our previous post, you can save your webcam access permission for the later use. You can create an app link in Chrome and whenever app window opened webcam will be active.

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HTML5 Webcam Case: Create a self-signed certificate

Thanks to HTML5 which gives us the opportunity to use native HTML for some features. Without Flash or Silverlight we can use webcam. The new getUserMedia() function is used for capturing and video tag for displaying webcam content. 

Target

Assume that we have a web client in a kiosk and we want to run our webpage by opening a Chrome window. Creating a shortcut is easy part but you'll see Chrome asks for permission to enable webcam each time. This is a problem because someone has to allow webcam after a restart for example.

Solution

Running your website in HTTPS environment can solve this. Then Chrome will remember your preference for that page. If you allow webcam then each time it will gives permission automatically.

Self-signed Certificate

If you don't have an authorized certificate for the HTTPS then you can create a self-signed certificate in IIS. 

• Download & Install Internet Information Services (IIS) 6.0 Resource Kit Tools 
• Run the SelfSSL tool 
• Run command  SelfSSL /N:CN=computer-name /V:365  Parameters; CN is your server name and V is for validity days. If you don't specify site-id then its the first site by default.

You can enter big numbers for validity days like 1000 (which is 3+years) but for some security reasons Chrome will give warnings for that. In our case use smaller numbers like 365days.

Now you can see the certificate in IIS > Server Certificates section.
In IIS go to your Website > Bindings and select your certificate in HTTPS type.

Now your server is ready for HTTPS call and client can see your page's url in "https://your-server-name/..." format.

But still not finished. Chrome will say it the certificate is not verified. This is a self-signed certificate and we need to add it to Trusted Certificates in client side. See the next post 

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Performance Counters on ASP.NET

If you want to use performance counters on your ASP.NET page you can use  System.Diagnostics.PerformanceCounter class. Example below shows running inside a generic handler.

static System.Diagnostics.PerformanceCounter cpuUsage;

public void ProcessRequest(HttpContext context)
{
    context.Response.ContentType = "text/plain";
    if (cpuUsage == null)
    {
        cpuUsage = new System.Diagnostics.PerformanceCounter();
        cpuUsage.CategoryName = "Processor";
        cpuUsage.CounterName = "% Processor Time";
        cpuUsage.InstanceName = "_Total";
    }

    context.Response.Write(cpuUsage.NextValue());
}

When you test in Visual Studio you will see you can get CPU usage for every call (except first call, it is 0 for the first time). But when you deploy your code to the server probably you will see the error below.

Access to the registry key 'Global' is denied. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.UnauthorizedAccessException: Access to the registry key 'Global' is denied.

To solve this problem;

1. Check your application pool from the IIS website settings (basic or advance).


2. Go to "Application Pools" section. Right click and select "Advanced Settings".


3. Find "Identity".


4. Go to "Server Manager" > "Local Users and Groups" > "Groups". On the right pane right click to "Performance Monitor Users" > Properties.



5. Add user you saw in the 3rd step (Identity). If you saw "ApplicationPoolIdentity" in the "Identity" then type "IIS APPPool\[Pool name]". In our example pool name is "ASP.NET v4.0".

6. Restart IIS. Now you should see the performance counter page without error.

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Query samples on a self referenced table (Part-4)

In previous post we joined tables but there was a problem. We can not see "Help" menu which has not any sub menu. To solve the problem we will use Outer Join.

Linq

var menus = from t in Menus
  where t.MenuType==1
  join s in Menus on t.MenuID equals s.MenuParent into Subs
  from ss in Subs.DefaultIfEmpty()
  select new {
   TopMenu = t.Title,
   SubMenu = ss == null ? null : ss.Title
  };

Lambda

Menus
   .Where (t => (t.MenuType == 1))
   .GroupJoin (
      Menus, 
      t => (t.MenuID), 
      s => s.MenuParent, 
      (t, Subs) => 
         new  
         {
            t = t, 
            Subs = Subs
         }
   )
   .SelectMany (
      temp0 => temp0.Subs.DefaultIfEmpty (), 
      (temp0, ss) => 
         new  
         {
            TopMenu = temp0.t.Title, 
            SubMenu = (ss == null) ? null : ss.Title
         }
   )

SQL

DECLARE @p0 Int = 1

SELECT [t0].[Title] AS [TopMenu], 
    (CASE 
        WHEN [t2].[test] IS NULL THEN NULL
        ELSE CONVERT(NVarChar(MAX),[t2].[Title])
     END) AS [SubMenu]
FROM [Menu] AS [t0]
LEFT OUTER JOIN (
    SELECT 1 AS [test], [t1].[Title], [t1].[MenuParent]
    FROM [Menu] AS [t1]
    ) AS [t2] ON ([t0].[MenuID]) = [t2].[MenuParent]
WHERE [t0].[MenuType] = @p0

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