Category Archives: Technologies

How to Select a .NET Framework

Motivation:

You need to select a .NET framework for your new project or for upgrading a legacy system.

However there are too many .NET framework branches so you are not sure which one is suitable with your need.

Guidelines:

You need to review the history of .NET framework and the differences among the various branches that include .NET Framework, ASP.NET Web Forms, ASP.NET MVC, .NET Core and .NET 6.

1. .NET Framework

The main purpose of .NET Framework is for building Windows Forms Applications.

  • .NET Framework 1.0 was released in 2002.
  • .NET Framework 2.0 was released in 2005.
  • .NET Framework 3.0 was released in 2006.
  • .NET Framework 3.5 was released in 2007.
  • .NET Framework 4.0 was released in 2010.
  • .NET Framework 4.5.2 was released in 2014.
  • .NET Framework 4.8 (the latest version) was released in 2019.
2. ASP.NET Web Forms

ASP.NET Web Forms was built on top of .NET Framework.

The main purpose of ASP.NET Web Forms is for building ASP.NET Web Forms Applications (multiple page web applications).

3. ASP.NET MVC

ASP.NET Web Forms does not follow MVC architecture pattern. Therefore MS built ASP.NET MVC.

ASP.NET MVC was built on top of .NET.

ASP.NET MVC is open-source software, apart from the ASP.NET Web Forms, which is proprietary.

The main purpose of ASP.NET MVC is for building ASP.NET MVC Applications (multiple page web applications based on MVC architecture pattern).

  • ASP.NET MVC 1.0 was released in 2009 (It was built on top of .NET Framework 3.5).
  • ASP.NET MVC 2.0 was released in 2010 (It was built on top of .NET Framework 4.0).
  • ASP.NET MVC 5.2.8 (the latest version) was released in 2022 (It was built on top of .NET Framework 4.8).
4. .NET Core

.NET Framework does not run on Linux or Unix and is proprietary. Therefore MS built .NET Core.

.NET Core runs on Windows, Linux and Unix, and is open-source software.

  • .NET Core 1.0 was released in 2016.
  • .NET Core 3.1 was released in 2019.
  • .NET Core then was renamed to just .NET in 2020 and .NET 5 was released in 2020. The .NET 4 name was not used to avoid name collision with .NET Framework.
  • .NET 6 (the latest version) was released in 2021.

The main purpose of .NET Core or .NET is for building Windows Forms Applications, ASP.NET MVC Applications and Single Page Applications that run on Windows, Linux and Unix.

The ASP.NET Web Forms Application type was removed from .NET Core or .NET.

5. .NET 6

Currently (in 2022) MS supports 2 branches of .NET:

  • .NET Framework 4.8 (containing Windows Forms Applications, Web Forms Applications, and ASP.NET MVC Applications) and
  • .NET 6 (containing Windows Forms Applications, ASP.NET MVC Applications and Single Page Applications).

Both .NET Framework 4.8 and .NET 6 support building microservices.

6. Final thoughts

For a new system, you probably should use .NET 6.

For a legacy system, if you are using ASP.NET Web Forms then you may stick with .NET Framework 4.8. Otherwise you may upgrade your system to .NET 6.

 

 

 

 

How to Fix IIS Express HTTPS Error

Problem:

You have created an ASP.NET web application with HTTPS.

You ran the application on https://localhost:5001 and got the “ERR_CONNECTION_RESET” error.

Solution:

1. Open Command Prompt with admin rights.

2. Type and press Enter

cd "C:\Program Files (x86)\IIS Express"

3. Type and press Enter

IISExpressAdminCmd.exe setupsslUrl -url:https://localhost:5001/ -UseSelfSigned

Change 5001 in the command above to the port you’re trying to use.

 

How to Move Outlook Data to a New Computer

Motivation:

You need to move Outlook data and settings from an old computer to a new computer.

Solution:

1. On the destination (new) computer:

    • Type Control Panel in Search box.
    • Click on Control Panel.
    • Select Large icons for View by.
    • Click Mail (32-bit).
    • Click Add. Set Profile Name = Outlook.
    • Follow the instructions to setup an account.

2. On the source (old) computer:

    • Open Outlook.
    • On the File menu, click Data File Management.
    • Click the data file that you want to compact, and then click Settings.
    • Click Compact Now.
    • Close Outlook.

3. Copy and overwrite all the contents of %USERPROFILE%\Local Settings\Application Data\Microsoft\Outlook to the destination computer. Create the Outlook folder if it does not exist.

4. Open Outlook in the destination computer.

Note: If you are using POP3 protocol then all the messages will be re-downloaded again once. If this is true for you then

    • Let Outlook finish downloading the messages, then
    • Click on Unread Mail folder below the Search Folders,
    • Select all the messages,
    • Press Shift, right click and click Delete to permanently delete them all.

 

How to Fix a Hacked WordPress Website

Problem:

When you visit your WordPress website you are randomly redirected to unwanted websites.

Verification:
  • Log in your website as an Administrator.
  • Go to Appearance >> Theme File Editor.
  • Click on the Theme Functions link on the right side.
  • Verify if malicious code was injected into the functions.php file. Example of malicious code:
    <?php @ini_set('display_errors', '0'); 
    error_reporting(0); 
    global $zeeta;
  • Download the wp-config.php file to your machine via FTP or SSH.
  • Verify if malicious code was injected into the wp-config.php file. Example of malicious code:
    include_once(ABSPATH . WPINC . '/header.php');
Solution:
  • Stop the website.
  • Download the whole website to your local machine.
    cd /var/hosting/huybien.com
    ls
    sudo zip -r huybien.zip /var/hosting/huybien.com/html
Configuration:
  • Log in your website as an Administrator.
  • Change your Administrator’s password.
  • Change permissions for the html folder.
    sudo chmod -R 777 /var/hosting/huybien.com/html
  • Remove all the unused plug-ins or themes.
  • Revert permissions for the html folder and set permissions for the wp-content folder.
    sudo chmod -R 755 /var/hosting/huybien.com/html
    sudo chmod -R 775 /var/hosting/huybien.com/html/wp-content
  • Install, activate and configure a CAPTCHA plug-in to protect Login Form, Registration Form, Lost Password Form, Reset Password Form and Comment Form if there is no one.
  • Disable insecure FTP access if there is one.
  • Install and activate the Simple History plugin to review access to your website. After 1 or 2 days, review the access information, and possibly block the malicious IP addresses using the Windows Firewall.
  • Install, activate and configure Cerber Security plug-in to automatically detect and block the malicious IP addresses.
  • Back up database.
    cd /home/ubuntu
    ls
    mysqldump -u root -p -h localhost huybiencomwp > huybiencomwp.sql
  • Back up files.
    cd /home/ubuntu
    ls
    sudo zip -r /home/ubuntu/huybien.zip /var/hosting/huybien.com/html
  • Download database and files backup.
  • Remove the backups.
    sudo rm -rf /home/ubuntu/huybiencomwp.sql
    sudo rm -rf /home/ubuntu/huybien.zip
    ls

 

 

How to Manually Install PHP 7.4 for Windows Server 2019

Motivation:

You want to understand how PHP works with IIS.

You want to prepare a PHP or WordPress development environment in Windows.

You want to update PHP to any version to address compatibility or security issues in Windows.

You may use Microsoft Web Platform Installer to install PHP for IIS. However the tool may restrict you from using only the supported versions.

Solution:

  • Install CGI for IIS on Turn Windows features on or off > Internet Information Services > World Wide Web Services > Application Development Features > CGI.
  • Download VC15 x86 Non Thread Safe package here or under PHP 7.4 section from http://windows.php.net/download/
  • Extract the ZIP file to the C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86 folder.
  • Rename the php-.ini-development file to php.ini.
  • Open the php.ini file and add the following line at the end of the file.
extension=php_wincache.dll
  • Uncomment the following lines
fastcgi.impersonate = 1;

cgi.fix_pathinfo=1;
cgi.force_redirect = 1 (and change the value to 0, i.e. cgi.force_redirect = 0)

extension_dir = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\ext"

extension=php_curl.dll
extension=php_fileinfo.dll
extension=php_mbstring.dll
extension=php_exif.dll
extension=php_mysqli.dll
extension=php_pdo_mysql.dll
extension=php_openssl.dll

error_log = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\php_errors.log"

error_log = syslog
  • A sample php.ini file can be download here.
  • Add C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86 to System Path.
  • Download x86 package of WinCache 2.0 for PHP 7.4 here or from https://sourceforge.net/projects/wincache/.
  • Extract and copy the php_wincache.dll file to C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\ext
    folder.
  • Open IIS, click on Server name, double click on Handler Mappings, click on Add Module Mapping, and enter below information
Request path = *.php
Module = FastCgiModule
Executable = "C:\Program Files (x86)\php-7.4.9-nts-Win32-vc15-x86\php-cgi.exe"
Name = PHP 7.4
Request Restrictions = File or folder
php --version
    • Create phpinfo.php file with below content in the root website folder.
    <?php 
    phpinfo(); 
    ?>

     

    How to Fully Uninstall Cocoapods from macOS

    Problem:

    You run pod update but you get command not found error.

    You want to fully uninstall the Cocoapods from macOS, and then to reinstall it to remove the error.

    Solution:

    Execute below commands:

    for i in $( gem list --local --no-version | grep cocoapods );
    do 
        sudo gem uninstall $i; 
    done
    rm -rf ~/.cocoapods

    If you have a Cocoapods icon on the Launchpad then

      • Click on the  Cocoapods icon on the Launchpad,
      • Right click the Cocoapods icon in the Dock,
      • Point your mouse to Options, then click Show in Finder,
      • Right click the Cocoapods icon and select Move to Trash.

    Execute below command to reinstall Cocoapods

    sudo gem install cocoapods

     

    How to fix “An internal error has occurred” issue of Remote Desktop Connection

    Problem:

    You get “An internal error has occurred” error message when trying to connect to a remote machine using Remote Desktop Connection.

    Solution:

    1. Type Local Security Policy to the Windows Search box.

    2. Click Open link.

    3. Expand Local Policies > Security Options on the left panel.

    4.  Double click on System cryptography: Use FIPS compliant algorithms for encryption, hashing, and signing row on the right panel.

    5. Select Enabled, click Apply and click OK.

    How to add multiple IPs to an Amazon EC2 virtual machine

    Motivation:

    You have a Server 2008 R2 machine on Amazon EC2.

    You want to secure multiple domains using different  SSL/TLS certificates.

    Server 2008 R2 does not support Server Name Indication (SNI). Therefore you need to add multiple IPs to Server 2008 R2 machine to use different SSL/TLS certificates.

    Solution:
    1. Create an EC2 virtual machine.
    2. Click on Network Interfaces tab.
    3. Click Create Network Interface button or select an existing network interface and select Actions > Attach.
    4. Click on a network interface ID, click Actions, click Manage IP Addresses, click on the network interface name (beginning with eth…), click the Assign new IP Address button, enter a private IP Address (e.g. 172.30.0.32), click the Save button, click the Confirm button.
    5. Click Elastic IPs tab, click the Allocate Elastic IP address button, click the Allocate button, optionally name the new allocated IP.
    6. Select the new allocated IP, click on Actions , click Associate Address, choose Network interface, then choose a private IP of the network interface with which the elastic IP will be associated, click the Associate button.
    7. Login Windows.
    8. View the network configuration using below command, note the Default Gateway and DNS Servers information.
    ipconfig /all

    9. Open Control Panel\All Control Panel Items\Network and Sharing Center.

    10. Click Change adapter settings link, click a Local Area Network Connection Network.

    11. Manually enter one IP address, Default Gateway and DNS Servers information.

    12. Click Advance… button to open Advanced TCP/IP Settings screen, and add the private IPs in the 4th step to the machine.

    13. Restart the machine.

    If you get any issue then try limit the number of private IPs of a network interface to 4 (including the default private IP).

    How to move a WordPress instance from one server to another Linux server

    Motivation:

    You want to move a WordPress instance from one server to another to consolidate your websites to reduce cost.

    Solution:

    Install and use below Duplicator plugin to achieve your goal.

    https://wordpress.org/plugins/duplicator/

    User guide: https://snapcreek.com/duplicator/docs/quick-start/

    If everything goes well for you then congratulation!

    Otherwise, please review below possible problems and corresponding solutions.


    Problem 1:

    You don’t have a website on the new server.

    Solution 1:

    1. Create a new virtual host in the /etc/httpd/conf/httpd.conf

    <VirtualHost *:80>
    ServerName example.com
    ServerAlias www.example.com
    DocumentRoot "/var/www/www.example.com"
    </VirtualHost>

    2. Set 775 permission for /var/www/www.example.com

    3. Restart httpd service

    sudo systemctl restart httpd

    Problem 2:

    You are using Amazon Linux 2 server.

    You are logged in as ec2-user.

    You use WinSCP to upload files and edit configuration files.

    You cannot modify /etc/httpd/conf/httpd.conf and /etc/php.ini.

    Solution 2:

    1 View permission settings for the file

    ls -ld /etc/httpd/conf/httpd.conf

    The result indicates that the file owner is root user and root group, not ec2-user.

    2. View groups of a user

    groups ec2-user

    The result indicates that the ec2-user does not belong to root group.

    3. Add a user to root group

    sudo usermod -a -G root ec2-user

    4. Grant Read-Write permission against a file to root group

    sudo chmod g+rwx /etc/httpd/conf/httpd.conf
    sudo chmod g+rwx /etc/php.ini

    5. Logout and login to the server again.


    Problem 3:

    You are using Amazon Linux 2 server. The ZipArchive feature is missing.

    Solution 3:

    1. Execute below commands:

    sudo amazon-linux-extras install php7.2
    sudo yum install php-pear php-devel gcc libzip-devel zlib-devel
    sudo pecl install zip-1.13.5 # we must specify a slightly older version due due to compatibility

    2. Add “extension=zip.so” to /etc/php.ini

    3. Restart the server

    sudo reboot

    Problem 4:

    You don’t have a WordPress database on the new Linux server.

    Solution 4:

    Execute below MySQL commands:

    CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
    CREATE DATABASE `wp_database`;
    GRANT ALL PRIVILEGES ON `wp_database`.* TO "username"@"localhost";
    FLUSH PRIVILEGES;

    Problem 5:

    An database error occurs while restoring a website.

    Solution 5:

    1. Execute below commands to remove the website:

    sudo chown -R ec2-user:apache /var/www/example.com
    sudo chmod 2775 /var/www/example.com && find /var/www/example.com -type d -exec sudo chmod 2775 {} \;
    find /var/www/example.com -type f -exec sudo chmod 0664 {} \;
    rm -r /var/www/example.com

    2. Upload the Duplicator files again, and restore the website again.


    Problem 6:

    No write access against /var/www/example.com is available for Duplicator.

    Solution 6:

    1. Execute below commands:

    sudo chown -R ec2-user:apache /var/www/example.com
    sudo chmod 2775 /var/www/example.com && find /var/www/example.com -type d -exec sudo chmod 2775 {} \;
    find /var/www/example.com -type f -exec sudo chmod 0664 {} \;

    2. Run http://example.com/installer.php again.

    How to Set File Permissions for WordPress on IIS

    Motivation:

    • You have a WordPress instance in Windows with IIS.
    • You upload a file. Its thumbnail is not shown in Media Library.
    • You change the file permission. Its thumbnail now is shown correctly in Media Library.
    • You upload another file and have to change the file permission manually again.
    • How can we make WordPress automatically set the correct permission for new uploaded files?

    Procedure:

    1. Ensure that the the Identity of Application pool that the website is running under is ApplicationPoolIdentity.
    2. Execute below commands as Administrator
    icacls "C:\inetpub\wwwroot\domain.com" /grant "IUSR":(OI)(CI)F /T 
    icacls "C:\inetpub\wwwroot\domain.com" /grant "IIS_IUSRS":(OI)(CI)F /T

    3. Open IIS Manager, click on your website, click Authentication, click Anonymous Authentication (which should be the only one enabled), click Edit, select Application pool identity if it is not selected, click OK.