FTP Client Certificate Authentication <clientCertAuthentication>

Article
03/23/2022

Overview

The <clientCertAuthentication> element specifies the settings for Client Certificate authentication. This form of Secure Sockets Layer (SSL) authentication was introduced in FTP 7 and uses client certificates to authenticate FTP clients by mapping to client certificates Windows user accounts.

Client Certificate authentication has the following dependencies:

For the <ssl> element:
- The serverCertHash attribute must be set to a valid certificate hash.
- The controlChannelPolicy and dataChannelPolicy attributes must be configured to allow SSL.
For the <sslClientCertificates> element:
- The clientCertificatePolicy attribute must be configured to allow SSL certificates.
- The useActiveDirectoryMapping attribute must be set to true.

Note

The FTP service requests Active Directory to validate client certificates, but the validation by Active Directory is performed independently of the FTP service.

Compatibility

Version	Notes
IIS 10.0	The `<clientCertAuthentication>` element was not modified in IIS 10.0.
IIS 8.5	The `<clientCertAuthentication>` element was not modified in IIS 8.5.
IIS 8.0	The `<clientCertAuthentication>` element was not modified in IIS 8.0.
IIS 7.5	The `<clientCertAuthentication>` element of the `<authentication>` element ships as a feature of IIS 7.5.
IIS 7.0	The `<clientCertAuthentication>` element of the `<authentication>` element was introduced in FTP 7.0, which was a separate download for IIS 7.0.
IIS 6.0	The `<ftpServer>` element and its child elements replace the IIS 6.0 FTP settings that were located in the LM/MSFTPSVC metabase path.

Note

The FTP 7.0 and FTP 7.5 services shipped out-of-band for IIS 7.0, which required downloading and installing the modules from the following URL:

https://www.iis.net/expand/FTP

With Windows 7 and Windows Server 2008 R2, the FTP 7.5 service ships as a feature for IIS 7.5, so downloading the FTP service is no longer necessary.

Setup

To support FTP publishing for your Web server, you must install the FTP service. To do so, use the following steps.

Windows Server 2012 or Windows Server 2012 R2

On the taskbar, click Server Manager.
In Server Manager, click the Manage menu, and then click Add Roles and Features.
In the Add Roles and Features wizard, click Next. Select the installation type and click Next. Select the destination server and click Next.
On the Server Roles page, expand Web Server (IIS), and then select FTP Server.

Note

To support ASP.Membership authentication or IIS Manager authentication for the FTP service, you will need to select FTP Extensibility, in addition to FTP Service.
.
Click Next, and then on the Select features page, click Next again.
On the Confirm installation selections page, click Install.
On the Results page, click Close.

Windows 8 or Windows 8.1

On the Start screen, move the pointer all the way to the lower left corner, right-click the Start button, and then click Control Panel.
In Control Panel, click Programs and Features, and then click Turn Windows features on or off.
Expand Internet Information Services, and then select FTP Server.

Note

To support ASP.Membership authentication or IIS Manager authentication for the FTP service, you will also need to select FTP Extensibility.
Click OK.
Click Close.

Windows Server 2008 R2

On the taskbar, click Start, point to Administrative Tools, and then click Server Manager.
In the Server Manager hierarchy pane, expand Roles, and then click Web Server (IIS).
In the Web Server (IIS) pane, scroll to the Role Services section, and then click Add Role Services.
On the Select Role Services page of the Add Role Services Wizard, expand FTP Server.
Select FTP Service.

Note

To support ASP.Membership authentication or IIS Manager authentication for the FTP service, you will also need to select FTP Extensibility.
Click Next.
On the Confirm Installation Selections page, click Install.
On the Results page, click Close.

Windows 7

On the taskbar, click Start, and then click Control Panel.
In Control Panel, click Programs and Features, and then click Turn Windows Features on or off.
Expand Internet Information Services, and then FTP Server.
Select FTP Service.

Note

To support ASP.Membership authentication or IIS Manager authentication for the FTP service, you will also need to select FTP Extensibility.
Click OK.

Windows Server 2008 or Windows Vista

Download the installation package from the following URL:
- https://www.iis.net/expand/FTP
Follow the instructions in the following walkthrough to install the FTP service:
- Installing and Troubleshooting FTP 7

How To

At this time there is no user interface that enables you to configure the Client Certificate authentication settings for an FTP site. See the Configuration and Sample Code sections of this document for additional information about how to configure the Client Certificate authentication settings for an FTP site.

Configuration

The <clientCertAuthentication> element is configured at the site level.

Attributes

Attribute	Description
`enabled`	Optional Boolean attribute. true if Client Certificate authentication is enabled; otherwise, false. The default value is `false`.

Child Elements

None.

Configuration Sample

The following sample displays an FTP server that requires SSL, and uses Client Certificate authentication to map users to Active Directory accounts.

<site name="ftp.example.com" id="5">
   <application path="/">
      <virtualDirectory path="/" physicalPath="c:\inetpub\www.example.com" />
   </application>
   <bindings>
      <binding protocol="ftp" bindingInformation="*:21:" />
   </bindings>
   <ftpServer serverAutoStart="true">
      <security>
         <authentication>
            <anonymousAuthentication enabled="false" />
            <basicAuthentication enabled="false" />
            <clientCertAuthentication enabled="true" />
         </authentication>
         <ssl serverCertHash="57686f6120447564652c2049495320526f636b73"
            controlChannelPolicy="SslRequire"
            dataChannelPolicy="SslRequire" />
         <sslClientCertificates clientCertificatePolicy="CertRequire"
            useActiveDirectoryMapping="true"
            validationFlags="NoRevocationCheck" />
      </security>
   </ftpServer>
</site>

Sample Code

The following examples configure an FTP site so that it disables both Anonymous and Basic authentication and enables Client Certificate authentication.

AppCmd.exe

appcmd.exe set config -section:system.applicationHost/sites /[name='ftp.example.com'].ftpServer.security.authentication.anonymousAuthentication.enabled:"False" /commit:apphost
appcmd.exe set config -section:system.applicationHost/sites /[name='ftp.example.com'].ftpServer.security.authentication.basicAuthentication.enabled:"False" /commit:apphost
appcmd.exe set config -section:system.applicationHost/sites /[name='ftp.example.com'].ftpServer.security.authentication.clientCertAuthentication.enabled:"True" /commit:apphost

Note

You must be sure to set the commit parameter to apphost when you use AppCmd.exe to configure these settings. This commits the configuration settings to the appropriate location section in the ApplicationHost.config file.

C#

using System;
using System.Text;
using Microsoft.Web.Administration;

internal static class Sample
{
   private static void Main()
   {
      using (ServerManager serverManager = new ServerManager())
      {
         Configuration config = serverManager.GetApplicationHostConfiguration();
         ConfigurationSection sitesSection = config.GetSection("system.applicationHost/sites");
         ConfigurationElementCollection sitesCollection = sitesSection.GetCollection();

         ConfigurationElement siteElement = FindElement(sitesCollection, "site", "name", @"ftp.example.com");
         if (siteElement == null) throw new InvalidOperationException("Element not found!");

         ConfigurationElement ftpServerElement = siteElement.GetChildElement("ftpServer");
         ConfigurationElement securityElement = ftpServerElement.GetChildElement("security");
         ConfigurationElement authenticationElement = securityElement.GetChildElement("authentication");

         ConfigurationElement anonymousAuthenticationElement = authenticationElement.GetChildElement("anonymousAuthentication");
         anonymousAuthenticationElement["enabled"] = false;

         ConfigurationElement basicAuthenticationElement = authenticationElement.GetChildElement("basicAuthentication");
         basicAuthenticationElement["enabled"] = false;

         ConfigurationElement clientCertAuthenticationElement = authenticationElement.GetChildElement("clientCertAuthentication");
         clientCertAuthenticationElement["enabled"] = true;

         serverManager.CommitChanges();
      }
   }
   
   private static ConfigurationElement FindElement(ConfigurationElementCollection collection, string elementTagName, params string[] keyValues)
   {
      foreach (ConfigurationElement element in collection)
      {
         if (String.Equals(element.ElementTagName, elementTagName, StringComparison.OrdinalIgnoreCase))
         {
            bool matches = true;
            for (int i = 0; i < keyValues.Length; i += 2)
            {
               object o = element.GetAttributeValue(keyValues[i]);
               string value = null;
               if (o != null)
               {
                  value = o.ToString();
               }
               if (!String.Equals(value, keyValues[i + 1], StringComparison.OrdinalIgnoreCase))
               {
                  matches = false;
                  break;
               }
            }
            if (matches)
            {
               return element;
            }
         }
      }
      return null;
   }
}

VB.NET

Imports System
Imports System.Text
Imports Microsoft.Web.Administration

Module Sample
   Sub Main()
      Dim serverManager As ServerManager = New ServerManager
      Dim config As Configuration = serverManager.GetApplicationHostConfiguration
      Dim sitesSection As ConfigurationSection = config.GetSection("system.applicationHost/sites")
      Dim sitesCollection As ConfigurationElementCollection = sitesSection.GetCollection

      Dim siteElement As ConfigurationElement = FindElement(sitesCollection, "site", "name", "ftp.example.com")
      If (siteElement Is Nothing) Then
         Throw New InvalidOperationException("Element not found!")
      End If

      Dim ftpServerElement As ConfigurationElement = siteElement.GetChildElement("ftpServer")
      Dim securityElement As ConfigurationElement = ftpServerElement.GetChildElement("security")
      Dim authenticationElement As ConfigurationElement = securityElement.GetChildElement("authentication")

      Dim anonymousAuthenticationElement As ConfigurationElement = authenticationElement.GetChildElement("anonymousAuthentication")
      anonymousAuthenticationElement("enabled") = False

      Dim basicAuthenticationElement As ConfigurationElement = authenticationElement.GetChildElement("basicAuthentication")
      basicAuthenticationElement("enabled") = False

      Dim clientCertAuthenticationElement As ConfigurationElement = authenticationElement.GetChildElement("clientCertAuthentication")
      clientCertAuthenticationElement("enabled") = True

      serverManager.CommitChanges()
   End Sub

   Private Function FindElement(ByVal collection As ConfigurationElementCollection, ByVal elementTagName As String, ByVal ParamArray keyValues() As String) As ConfigurationElement
      For Each element As ConfigurationElement In collection
         If String.Equals(element.ElementTagName, elementTagName, StringComparison.OrdinalIgnoreCase) Then
            Dim matches As Boolean = True
            Dim i As Integer
            For i = 0 To keyValues.Length - 1 Step 2
               Dim o As Object = element.GetAttributeValue(keyValues(i))
               Dim value As String = Nothing
               If (Not (o) Is Nothing) Then
                  value = o.ToString
               End If
               If Not String.Equals(value, keyValues((i + 1)), StringComparison.OrdinalIgnoreCase) Then
                  matches = False
                  Exit For
               End If
            Next
            If matches Then
               Return element
            End If
         End If
      Next
      Return Nothing
   End Function


End Module

JavaScript

var adminManager = new ActiveXObject('Microsoft.ApplicationHost.WritableAdminManager');
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST";
var sitesSection = adminManager.GetAdminSection("system.applicationHost/sites", "MACHINE/WEBROOT/APPHOST");
var sitesCollection = sitesSection.Collection;

var siteElementPos = FindElement(sitesCollection, "site", ["name", "ftp.example.com"]);
if (siteElementPos == -1) throw "Element not found!";
var siteElement = sitesCollection.Item(siteElementPos);

var ftpServerElement = siteElement.ChildElements.Item("ftpServer");
var securityElement = ftpServerElement.ChildElements.Item("security");
var authenticationElement = securityElement.ChildElements.Item("authentication");

var anonymousAuthenticationElement = authenticationElement.ChildElements.Item("anonymousAuthentication");
anonymousAuthenticationElement.Properties.Item("enabled").Value = false;

var basicAuthenticationElement = authenticationElement.ChildElements.Item("basicAuthentication");
basicAuthenticationElement.Properties.Item("enabled").Value = false;

var clientCertAuthenticationElement = authenticationElement.ChildElements.Item("clientCertAuthentication");
clientCertAuthenticationElement.Properties.Item("enabled").Value = true;

adminManager.CommitChanges();

function FindElement(collection, elementTagName, valuesToMatch) {
   for (var i = 0; i < collection.Count; i++) {
      var element = collection.Item(i);
      if (element.Name == elementTagName) {
         var matches = true;
         for (var iVal = 0; iVal < valuesToMatch.length; iVal += 2) {
            var property = element.GetPropertyByName(valuesToMatch[iVal]);
            var value = property.Value;
            if (value != null) {
               value = value.toString();
            }
            if (value != valuesToMatch[iVal + 1]) {
               matches = false;
               break;
            }
         }
         if (matches) {
            return i;
         }
      }
   }
   return -1;
}

VBScript

Set adminManager = createObject("Microsoft.ApplicationHost.WritableAdminManager")
adminManager.CommitPath = "MACHINE/WEBROOT/APPHOST"
Set sitesSection = adminManager.GetAdminSection("system.applicationHost/sites", "MACHINE/WEBROOT/APPHOST")
Set sitesCollection = sitesSection.Collection

siteElementPos = FindElement(sitesCollection, "site", Array("name", "ftp.example.com"))
If siteElementPos = -1 Then
   WScript.Echo "Element not found!"
   WScript.Quit
End If
Set siteElement = sitesCollection.Item(siteElementPos)

Set ftpServerElement = siteElement.ChildElements.Item("ftpServer")
Set securityElement = ftpServerElement.ChildElements.Item("security")
Set authenticationElement = securityElement.ChildElements.Item("authentication")

Set anonymousAuthenticationElement = authenticationElement.ChildElements.Item("anonymousAuthentication")
anonymousAuthenticationElement.Properties.Item("enabled").Value = False

Set basicAuthenticationElement = authenticationElement.ChildElements.Item("basicAuthentication")
basicAuthenticationElement.Properties.Item("enabled").Value = False

Set clientCertAuthenticationElement = authenticationElement.ChildElements.Item("clientCertAuthentication")
clientCertAuthenticationElement.Properties.Item("enabled").Value = True

adminManager.CommitChanges()

Function FindElement(collection, elementTagName, valuesToMatch)
   For i = 0 To CInt(collection.Count) - 1
      Set element = collection.Item(i)
      If element.Name = elementTagName Then
         matches = True
         For iVal = 0 To UBound(valuesToMatch) Step 2
            Set property = element.GetPropertyByName(valuesToMatch(iVal))
            value = property.Value
            If Not IsNull(value) Then
               value = CStr(value)
            End If
            If Not value = CStr(valuesToMatch(iVal + 1)) Then
               matches = False
               Exit For
            End If
         Next
         If matches Then
            Exit For
         End If
      End If
   Next
   If matches Then
      FindElement = i
   Else
      FindElement = -1
   End If
End Function

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FTP Client Certificate Authentication <clientCertAuthentication>

Overview

Compatibility

Setup

Windows Server 2012 or Windows Server 2012 R2

Windows 8 or Windows 8.1

Windows Server 2008 R2

Windows 7

Windows Server 2008 or Windows Vista

How To

Configuration

Attributes

Child Elements

Configuration Sample

Sample Code

AppCmd.exe

C#

VB.NET

JavaScript

VBScript

Feedback

Additional resources