How to Use Managed Code (Visual Basic) to Create a Simple FTP Home Directory Provider

By Robert McMurray

September 11, 2009

Microsoft has created a new FTP service that has been completely rewritten for Windows Server® 2008. This new FTP service incorporates many new features that enable Web authors to publish content more easily than before, and offers Web administrators more security and deployment options.

The new FTP 7.5 service supports extensibility that lets you extend the built-in functionality that is included with the FTP service. More specifically, FTP 7.5 supports the creation of your own authentication and authorization providers. You can also create providers for custom FTP logging and for determining the home directory information for your FTP users.

This walkthrough will lead you through the steps to use managed code to create a simple FTP home directory provider.

Prerequisites

The following items are required to complete the procedures in this article:

  1. IIS 7 or above must be installed on your server, and the Internet Information Services (IIS) Manager must also be installed.
  2. The new FTP 7.5 service must be installed. If you are using Windows Server 2008, you can download and install the FTP 7.5 service from the http://www.iis.net/ web site using one of the following links:
  3. You must create a root folder for FTP publishing.
  4. You must use Visual Studio 2008. (Note: If you use an earlier version of Visual Studio, some of the steps in this walkthrough may not be correct.)
  5. A home directory for each user must be created; the code sample uses C:\Ftpusers\%UserName%, but you could change that as necessary.

Step 1: Set up the Project Environment

In this step, you will create a project in Visual Studio 2008 for the demo provider.

  1. Open Microsoft Visual Studio 2008.
  2. Click the File menu, then New, then Project.
  3. In the New Project dialog box:
    • Choose Visual Basic as the project type.
    • Choose Class Library as the template.
    • Type FtpHomeDirectoryDemo as the name of the project.
    • Click OK.
  4. When the project opens, add the required references to the project:
    • Click Project, and then click FtpHomeDirectoryDemo Properties.
    • Click the References tab.
    • Add a reference path to the FTP extensibility library:
      • On the References tab, click the Reference Paths button.
      • Enter the path to the FTP extensibility assembly for your version of Windows, where C: is your operating system drive:
        • For Windows Server 2008 and Windows Vista:
          • C:\Windows\assembly\GAC_MSIL\Microsoft.Web.FtpServer\7.5.0.0__31bf3856ad364e35
        • For Windows 7:
          • C:\Program Files\Reference Assemblies\Microsoft\IIS
      • Click Add Folder.
      • Click OK.
    • Add a reference to the FTP extensibility library for the project:
      • On the References tab, click the Add button.
      • Select Microsoft.Web.FtpServer in the list of components.
      • Click OK.
    • Add a reference to System.Web for the project:
      • On the References tab, click the Add button.
      • Select System.Web in the list of components.
      • Click OK.
  5. Add a strong name key to the project:
    • Click Project, and then click FtpHomeDirectoryDemo Properties.
    • Click the Signing tab.
    • Check the Sign the assembly check box.
    • Choose <New...> from the strong key name drop-down box.
    • Enter FtpHomeDirectoryDemoKey for the key file name.
    • If desired, enter a password for the key file; otherwise, clear the Protect my key file with a password check box.
    • Click OK.
  6. Optional: You can add a custom build event to add the DLL automatically to the Global Assembly Cache (GAC) on your development computer:
    • Click Project, and then click FtpHomeDirectoryDemo Properties.
    • Click the Compile tab.
    • Click the Build Events button.
    • Enter the following in the Post-build event command line dialog box:
      net stop ftpsvc
      call "%VS90COMNTOOLS%\vsvars32.bat">null
      gacutil.exe /if "$(TargetPath)"
      net start ftpsvc
    • Click OK.
  7. Save the project.

Step 2: Create the Extensibility Class

In this step, you will implement the extensibility interface for the demo provider.

  1. Add the code for the authentication class:
    • In Solution Explorer, double-click the Class1.vb file.
    • Remove the existing code.
    • Paste the following code into the editor:
      Imports System
      Imports Microsoft.Web.FtpServer
      
      Namespace FtpHomeDirectory
        Public Class FtpHomeDirDemo
          Inherits BaseProvider
          Implements IFtpHomeDirectoryProvider
      
          Function IFtpHomeDirectoryProvider_GetUserHomeDirectoryData( _
            ByVal sessionId As String, _
            ByVal siteName As String, _
            ByVal userName As String) _
              As String _
              Implements IFtpHomeDirectoryProvider.GetUserHomeDirectoryData
      
            ' Note: You would add your own custom logic here.
      
            ' Return the user's home directory based on their user name.
            Return ("C:\Ftpusers\" + userName)
      
          End Function
      
        End Class
      End Namespace
  2. Save and compile the project.

Note: If you did not use the optional steps to register the assemblies in the GAC, you will need to manually copy the assemblies to your IIS computer and add the assemblies to the GAC using the Gacutil.exe tool. For more information, see the following topic on Microsoft the MSDN Web site:

Global Assembly Cache Tool (Gacutil.exe)

Step 3: Add the Home Directory Provider to FTP

In this step, you will add the demo provider to your FTP service and the default Web site.

  1. Determine the assembly information for the extensibility provider:
    • In Windows Explorer, open your "C:\Windows\assembly" path, where C: is your operating system drive.
    • Locate the FtpHomeDirectoryDemo assembly.
    • Right-click the assembly, and then click Properties.
    • Copy the Culture value; for example: Neutral.
    • Copy the Version number; for example: 1.0.0.0.
    • Copy the Public Key Token value; for example: 426f62526f636b73.
    • Click Cancel.
  2. Add the extensibility provider to the global list of FTP providers:
    • Open the Internet Information Services (IIS) Manager.
    • Click your computer name in the Connections pane.
    • Double-click FTP Authentication in the main window.
    • Click Custom Providers... in the Actions pane.
    • Click Register.
    • Enter FtpHomeDirectoryDemo for the provider Name.
    • Click Managed Provider (.NET).
    • Enter the assembly information for the extensibility provider using the information that you copied earlier. For example:
      FtpHomeDirectoryDemo.FtpHomeDirectory.FtpHomeDirDemo,FtpHomeDirectoryDemo,version=1.0.0.0,Culture=neutral,PublicKeyToken=426f62526f636b73
    • Click OK.
    • Clear the FtpHomeDirectoryDemo check box in the providers list.
    • Click OK.
  3. Add the custom provider to a site:
    • At the moment there is no UI that enables you to add custom features to a site, so you will have to use the following command line:
      AppCmd set site "Default Web Site" /+ftpServer.customFeatures.providers.[name='FtpHomeDirectoryDemo',enabled='true']
  4. Configure user isolation to use a custom provider:
    • At the moment there is no UI that enables you to specify custom features for user isolation, so you will have to use the following command line:
      AppCmd set site "Default Web Site" /ftpServer.userIsolation.mode:Custom

Summary

In this walkthrough you learned how to:

  • Create a project in Visual Studio 2008 for a custom FTP home directory provider.
  • Implement the extensibility interface for custom FTP home directory lookups.
  • Add a custom home directory provider to your FTP service.

When users connect to your FTP site, the FTP service will set each user's home directory to the path that you specified in the demo provider.



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