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NTLM authentication

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This document describes how to set up NTLM/Windows Integrated Authentication in Moodle.


Contents

Overview

Integrated Windows Authentication uses the security features of Windows clients and servers. It does not prompt users for a user name and password. The current Windows user information on the client computer is supplied by the browser through a challenge/response authentication process with the Web server for the Moodle site.

Assumptions

  1. You are running MS Active Directory for Authentication.
  2. The Server hosting your website is a member of the Active Directory Domain that your users are also members of.
  3. You are able to define people inside your Network (and authenticated to the Domain) from an IP range of computers.
  4. You are familar with or have read the LDAP authentication documentation.
  5. The Active Directory domain credentials of your users are returned as DOMAINNAME\username from your authentication service. If you are using the Winbind service from the Samba project, this can be untrue, depending on your Winbind configuration settings.

If you can not modify your settings to satisfy this last assumption, then you will need to remove or comment out the line that reads:

   $username = substr(strrchr($username, '\\'), 1); //strip domain info

and add the relevant lines of code to extract the username part from the domain user credentials and store it in $username.


VERY IMPORTANT: NTLM authentication depends on LDAP authentication, and NTLM configuration is specified in the LDAP authentication settings page (Site Administration >> Plugins >> Authentication >> LDAP Server). So before trying to configure NTLM, make sure you have LDAP_authentication properly setup and working.

Installation

No installation needed. See Site Administration >> Plugins >> Authentication >> LDAP Server for the NTLM config options. You only have to

  • Enable NTLM SSO
  • Set the IP/Subnet mask for the clients (see below)
  • On IIS: turn on Windows Authentication
  • On Apache - use one of the 3 methods outlined below
  • On the client pc's, you might need to set the moodle server ip/moodle url as being in "local intranet" (From IE, tools -> options -> security -> local intranet)

It is important to note the following conditions must be satisfied to let NTLM SSO happens:

  • you've arrived to the login page with one GET request
  • you've ldap->ntlmsso_enabled
  • you've ldap->ntlmsso_subnet
  • you aren't logged
  • the IP of the client is in ntlmsso_subnet

Thus it is needed to set the IP subnet.

If you have used previous versions of NTLM (from 1.8 and below) in your Moodle database you will need to make two further changes.

  1. The type of authentication held against each user now needs to be LDAP, as NTLM will not be recognised. To edit the fields open up a SQL query for your Moodle server and use the following query "update mdl_user set auth = 'ldap' where auth = 'ntlm' "
  2. If you had a previous .htaccess file in the auth/ntlm directory, you will need to move it to the auth/ldap directory. Regardless of whether it is in a .htaccess file of the httpd.conf, the <Files> line now needs to refer to ntlmsso_magic.php. If it is in the httpd.conf, the <Directory> will need to change too. This is covered later on for new installs, but is one of the fundamental changes that needs to be made for those upgrading.

How to Turn Integrated Authentication on

The auth/ldap/ntlmsso_magic.php file MUST have NTLM/Integrated Authentication enabled on the server or the authentication will not work.

IIS Configuration

Open the IIS Management Console and navigate to the auth/ldap/ntlmsso_magic.php file.

IIS 6.0

  1. right click on the file, choose properties
  2. under the "file security" tab, click on the Authentication and Access control "edit" button
  3. untick "Enable Anonymous Access" and tick "Integrated Windows Authentication"

IIS 7.x

  1. After navigating to the 'auth/ldap' folder, switch to Content View
  2. right click on the file, choose "Switch to Features View"
  3. click on the Authentication icon on the right
  4. select 'Anonymous Authentication' and click the 'Disable' button
  5. select 'Windows Authentication' and click the 'Enable' button
  • According to this post, if you are using IIS 7.5 (it comes with Windows Server 2008 R2), you have to select 'Windows Authentication' and click on 'Providers'. This shows a list of enabled providers (Negotiate and NTLM, by default). Change the order so that NTLM is at the top of the list.
  • If 'Windows Authentication' is not available, then you need to install it as a separate authentication provider (in Control Panel).

APACHE Configuration

There are currently 3 possible methods for this:

Using the NTLM part of Samba for Apache on Linux

  • Get the plugin here: http://samba.org/ftp/unpacked/lorikeet/mod_auth_ntlm_winbind/ . You need to download all the files from the link, but not the contrib and debian directories. Then follow the instructions given inside the README file. If you are using Debian/Ubuntu, you can follow these compilation instructions.
  • Once you have compiled it, put it inside Apache's modules subdirectory (this location depends on a number of factors, like compiling Apache yourself, using different Linux distributions packages, an so on), and load and enable the module in Apache's configuration. For example, if your Apache modules are under /usr/lib/apache2/modules, you'll need something like this in your Apache configuration file (usually called apache2.conf or http2.conf):
  <IfModule !mod_auth_ntlm_winbind.c>
      LoadModule auth_ntlm_winbind_module /usr/lib/apache2/modules/mod_auth_ntlm_winbind.so
  </IfModule>
  • Install the Samba winbind daemon package. This packages relies on Samba's configuration file to get some important settings (like the Windows domain name, uid and gid range mappings, and so on). In addition to that, you'll need to make your Linux/Unix machine part of the domain. Otherwise winbind won't be able to pull user and groups informationi from the domain controllers. You should read the Samba documentation to perform this step, but the most important part is having something like the following lines in your smb.conf file (in addition to what you already have there):
 workgroup = DOMAINNAME
 password server = *
 security = domain
 encrypt passwords = true
 idmap uid = 10000-20000
 idmap gid = 10000-20000
and executing the command (as root):
 # net join DOMAINNAME -U Administrator
where DOMAINNAME is the NetBIOS windows domain name, and Administrator an account with enough privileges to add new machines to the domain.
You'll need to type this account's password for the command to succeed.
In Windows environments you could also try executing the command (as root):
 # net join DOMAINNAME -S DCSERVER -U Administrator
where DCSERVER is the Domain Controller server
Also, make sure you have disabled "Microsoft Network Server: digitally sign communications (always)" in your Domain Controllers Security Policy, unless you are using a version of Samba that can sign SMB packets.
  • Restart the winbind service to apply the changes and test that it's running ok by executing:
 $ wbinfo -u
You should get the full list of Windows domain users. If you use -g instead, you'll get the domain groups list.
  • Check that your winbind package installed the authentication helper command ntlm_auth, as we'll need it later. We'll assume the helper is located at /usr/bin/ntlm_auth. If yours is at a different location, make sure you adjust the path in the example below.
  • Add something like this to your Apache configuration file (usually called apache2.conf or http2.conf). We'll assume that your Moodle $CFG->dirroot directory is located at /var/www/moodle in the example:
For 1.9 or above use:
   <Directory "/var/www/moodle/auth/ldap/">
       <Files ntlmsso_magic.php>
           NTLMAuth on
           AuthType NTLM
           AuthName "Moodle NTLM Authentication"
           NTLMAuthHelper "/usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp"
           NTLMBasicAuthoritative on
           require valid-user
       </Files>
   </Directory>
For 1.8 or below use:
   <Directory "/var/www/moodle/auth/ntlm/">
       <Files oncampuslogin.php>
           NTLMAuth on
           AuthType NTLM
           AuthName "Moodle NTLM Authentication"
           NTLMAuthHelper "/usr/bin/ntlm_auth --helper-protocol=squid-2.5-ntlmssp"
           NTLMBasicAuthoritative on
           require valid-user
       </Files>
   </Directory>
  • Check the permissions of the Winbind pipe directory (Ubuntu places it under /var/run/samba/winbindd_privileged, yours may be placed at a different location). Apache will need to be able to enter that directory, so we need to make sure it has the right permissions. So have a look at the permissions of that directory and note the name of the group assigned to it. The following example is from a Ubuntu 7.10 machine:
 $ ls -ald /var/run/samba/winbindd_privileged
 drwxr-x--- 2 root winbindd_priv 60 2007-11-17 16:18 /var/run/samba/winbindd_privileged/
so we see the group is winbindd_priv.
  • Instead of modifying the directory permissions (which could break other services that use winbind) we are going to make the Apache user (www-data in our example, but could be httpd, or nobody, etc.) is part of the appropiate group. Execute the following as root:
 # adduser www-data winbindd_priv
adduser is available in Debian and Ubuntu at least. If your distribution doesn't have adduser, you can edit /etc/group manually to achive the same effect.
  • Stop and start the Apache service to apply the changes. Have a look at Apache's error log to see that everything is ok.

simply change the line to that was:

KeepAlive Off

to:

KeepAlive On

and restart apache (/etc/init.d/http restart)

  • Email Dan if you get this working - I'm keen to hear how people go using the samba winbind option!
-- Hi Dan! I made it work using Ubuntu 7.04. That's what I've used to update the documentation. Iñaki Arenaza 10:43, 30 September 2007 (CDT)
-- Hi Dan! I have this working on Ubuntu 8.04 LTS in an RM CC4 Active Directory Domain. Ian 16:31 15 December 2009 (GMT)

Using the NTLM Auth Module for Apache on Linux

The NTLM Auth module is a bit stale and even its authors suggest that you use the NTLM part of Samba with Apache on Linux

Get it from here

  1. get the Module from: http://modntlm.sourceforge.net/
  2. follow the instructions given there and inside the README that comes with the package.

I (Iñaki Arenaza) strongly recommend using the NTLM part of Samba with Apache on Linux over this module. It's better maintained, more robust and has more features.

Using the mod_auth_sspi Module for Apache 2 on Windows

NOTE: This setup is currently being used in a live production environment, and is therefore suitable for such use provided it is correctly configured and tested.

This is the recommended method for Apache 2 on Windows, however it will not work on Linux/UNIX systems. It provides better stability and higher performance than other NTLM modules.

  • mod_auth_sspi-1.0.4-2.0.58.zip : Use this file if you are using Apache 2.0.x.
  • mod_auth_sspi-1.0.4-2.2.2.zip : Use this file if you are using Apache 2.2.x.
  • Unzip the right file and copy mod_auth_sspi.so (it's inside bin subdirectory) to your Apache modules directory.
  • Edit your Apache 2 configuration file (httpd.conf) to load the module.
   <IfModule !mod_auth_sspi.c>
       LoadModule sspi_auth_module modules/mod_auth_sspi.so
   </IfModule>
  • Choose one of the two methods below
Method 1: This method is recommended for servers that will host a single Moodle instance. Configure NTLM from the main configuration file, add the following to httpd.conf (substitute "C:\moodle" with the path to your Moodle installation e.g. "C:\my-moodle"
For 1.9 or above use:
   <Directory "C:\moodle\auth\ldap">
       <Files ntlmsso_magic.php>
           AuthName "Moodle at My College"
           AuthType SSPI
           SSPIAuth On
           SSPIOfferBasic Off
           SSPIAuthoritative On
           SSPIDomain mycollege.ac.uk
           require valid-user
       </Files>
   </Directory>
For 1.8 or below use:
   <Directory "C:\moodle\auth\ntlm">
       <Files oncampuslogin.php>
           AuthName "Moodle at My College"
           AuthType SSPI
           SSPIAuth On
           SSPIOfferBasic Off
           SSPIAuthoritative On
           SSPIDomain mycollege.ac.uk
           require valid-user
       </Files>
   </Directory>
Method 2: The alternative method is to use a .htaccess file
This method is recommended for servers that will host multiple Moodle instances. It allows additional Moodle instances to be configured without restarting apache, and also makes the solution a little more portable. We need to add a directive to the main httpd.conf to allow configuration of authentication within .htaccess files.
   <Directory C:\moodle>
       AllowOverride AuthConfig
   </Directory>
Create a new text file named '.htaccess' in the directory 'C:\moodle\moodle\auth\ldap' and add the following directives:
   <Files ntlmsso_magic.php>
       AuthName "Moodle at My College"
       AuthType SSPI
       SSPIAuth On
       SSPIOfferBasic Off
       SSPIAuthoritative On
       SSPIDomain mycollege.ac.uk
       require valid-user
   </Files>
This enables the Moodle folder to be moved to any apache webserver that is configured to allow authentication configuration through .htaccess

For further help and discussion: http://moodle.org/mod/forum/discuss.php?d=56565

Using the Kerberos Auth Module for Apache on Linux/UNIX (mod_auth_kerb)

Environment details in this example:

  1. Active Directory Domain: EXAMPLE.AC.UK
  2. Active Directory Domain Controller: dc.example.ac.uk
  3. Linux/UNIX web server: moodle.example.ac.uk
  4. Active Directory user account for web server service principal: moodlekerb

Install kerberos on moodle.example.ac.uk and enter the following in krb5.conf (by default: /etc/krb5.conf)

[libdefaults]
    default_realm = EXAMPLE.AC.UK
[domain_realm]
    example.ac.uk = EXAMPLE.AC.UK
[realms]
     EXAMPLE.AC.UK = {
                      admin_server = dc.example.ac.uk
                      kdc          = dc.example.ac.uk
                    }:
* Test kerberos
Issue the following command at the shell prompt:
<pre>
$> kinit user@EXAMPLE.AC.UK

Where 'user' is an Active Directory account for which you know the password.

Next, issue the following:

$>klist

If all is OK it will list the Kerberos ticket you were granted from the domain controller (KDC)

  • Create HTTP service principal for moodle.example.ac.uk
  1. Create the 'moodlekerb' user account in Active Directory (NOT a machine account) to map to the web server service principal (HTTP/moodle.example.ac.uk@EXAMPLE.AC.UK)

NOTE: moodle.example.ac.uk MUST be the canonical DNS name of the server i.e. an A record (NOT a CNAME). Additionally a valid PTR (reverse DNS) record must exist and match the corresponding A record.

  1. Use the ktpass.exe utility to map the service principal and create a keytab file

Apache requires a keytab file, which is generated with ktpass.exe on the Windows Active Directory Domain Controller. Shockingly, this component of Windows Server 2003 SP1 does not function correctly so one must obtain a hot fix: http://support.microsoft.com/kb/919557

Run the following command on the domain controller:

C:\path\to\hotfix\ktpass.exe -princ HTTP/moodle.example.ac.uk@EXAMPLE.AC.UK -mapuser EXAMPLE\moodlekerb -crypto DES-CBC-MD5 +DesOnly +setPass +rndPass -ptype KRB5_NT_PRINCIPAL -out moodle.example.ac.uk.keytab

Copy C:\path\to\hotfix\moodle.example.ac.uk.keytab to the moodle web server and remember the location (/etc/httpd/moodle.example.ac.uk.keytab or similar)

  • Configure Apache / mod_auth_kerb

Edit the Apache configuration for the moodle host and add the following directives:

        <Directory /path/to/moodle/docs/auth/ldap/>
                <Files ntlmsso_magic.php>
                        AuthName "Moodle"
                        AuthType Kerberos
                        KrbAuthRealms EXAMPLE.AC.UK
                        KrbServiceName HTTP
                        Krb5Keytab /etc/httpd/moodle.example.ac.uk.keytab
                        KrbMethodNegotiate on
                        KrbMethodK5Passwd on
                        KrbAuthoritative on
                        require valid-user
                </Files>
        </Directory>
  • Replace the ntlmsso_magic function in /auth/ldap/auth.php (1.9 only, as 2.x already support Kerberos format out of the box) with the following code:
    function ntlmsso_magic($sesskey) {
        if (isset($_SERVER['REMOTE_USER']) && !empty($_SERVER['REMOTE_USER'])) {

            // HTTP __headers__ seem to be sent in ISO-8859-1 encoding
            // (according to my reading of RFC-1945, RFC-2616 and RFC-2617 and
            // my local tests), so we need to convert the REMOTE_USER value
            // (i.e., what we got from the HTTP WWW-Authenticate header) into UTF-8
            $textlib = textlib_get_instance();
            $username = $textlib->convert($_SERVER['REMOTE_USER'], 'iso-8859-1', 'utf-8');
            
            /**
             * begin kerberos - afhole@wortech.ac.uk 21-04-2009
             */
            if ($pos = strpos($username, "@")) {
                $username = substr($username, 0, $pos);
            } else {
                $username = substr(strrchr($username, '\\'), 1); //strip domain info
            }
            /**
             * end kerberos
             */

            $username = moodle_strtolower($username); //compatibility hack
            set_cache_flag('auth/ldap/ntlmsess', $sesskey, $username, AUTH_NTLMTIMEOUT);
            return true;
        }
        return false;
    }

The above code change will account for the fact that Kerberos presents the username to REMOTE_USER in the format user@DOMAIN, rather than NTLM's DOMAIN\user

Configuring IP/Subnet Mask

Subnet masks are based on binary patterns so need a bit of knowledge to understand. The best way to find out what IP/Subnet masks to use is to ask your Network Admin.

  • The new way of specifiying subnets is even easier/more flexible than before 1.9. Just type them one after the other, separated by commas. You can use several syntaxes:
    • Type the network-number/prefix-length combination. E.g. 192.168.1.0/24
    • Type the network 'prefix', ending in a period character. E.g. 192.168.1.
    • Type the network address range (this only works for the last address octect). E.g. 192.168.1.1-254
All the three examples refer to the same subnetwork. So assuming you need to specify the following subnetworks:
  • 10.1.0/255.255.0.0
  • 10.2.0.0/255.255.0.0
  • 172.16.0.0/255.255.0.0
  • 192.168.100.0/255.255.255.240
You can type:
10.1.0.0/16, 10.2.0.0/16, 172.16.0.0/16, 192.168.100.0/28
or:
 10.1.0.0/16, 10.2.0.0/16, 172.16.0.0/16, 192.168.100.240-255
or even:
 10.1., 10.2., 172.16., 192.168.100.0/28
(the last one cannot be expressed as a network 'prefix' as the netmask does not fall on an octect boundary).

Notes/Tips

  1. If you are using Firefox, you will need to follow these steps:
  • Load Firefox and type about:config in the address box. The configuration settings page should be displayed.
  • In the Filter box, type the word "ntlm" to filter the NTLM strings. You should see three settings displayed.
  • Double-click on "network.automatic-ntlm-auth.trusted-uris".
  • In the box, enter the full URL of your Moodle server. For example
    http://moodle.mydomain.com, (the comma is important)
  • Close Firefox and restart.
  1. NTLM seems to not work at all when BASIC authentication is enabled. (this was using the Kerberos method, other ways may work)
  2. If the account in your AD management console shows like "First Last", you better change the ldap settings parameter 'User Attribute' from its default of {blank} / 'cn' to 'sAMAccountName' as indicated in this post. The reason is that the cn name generally looks like "First Last", once you done the ldap sync, the user name in moodle will be "first last", but IE passes the account of "domain\first.last" to moodle which does not exist in moodle.

To get a domain name for Moodle working on IIS7.5 Windows 2008 R2

Refer to http://support.microsoft.com/kb/896861. Key section listed below. Click Start, click Run, type regedit, and then click OK.
In Registry Editor, locate and then click the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0
Right-click MSV1_0, point to New, and then click Multi-String Value.
Type BackConnectionHostNames, and then press ENTER.
Right-click BackConnectionHostNames, and then click Modify.
In the Value data box, type the host name or the host names for the sites that are on the local computer, and then click OK.
Quit Registry Editor, and then restart the IISAdmin service.

Compiling mod_auth_ntlm_winbind on Debian/Ubuntu

You need to install the following packages (and all of their dependencies) by using aptitude, synaptic, etc.:

 autoconf apache2-threaded-dev debian-builder

Once you have them installed, open up a text console, go to the directory where you downloaded the mod_auth_ntlm_winbind files an execute the following commands (as a normal user):

 autoconf
 ./configure --with-apxs=/usr/bin/apxs2 --with-apache=/usr/sbin/apache2
 make

That should compile it without errors. Then as a user that can run commands as root via sudo, execute the following command from the same directory:

 sudo make install

This will create the final mod_auth_ntlm_winbind.so file and install it under /usr/lib/apache2/modules, with the rest of the Apache 2 modules (the size of the file and last modification time shown below may differ from your install):

 ls -l /usr/lib/apache2/modules/mod_auth_ntlm_winbind.so
 -rw-r--r-- 1 root root 20921 2009-02-17 04:27 /usr/lib/apache2/modules/mod_auth_ntlm_winbind.so

See also