Chapter 2. Connecting RHEL systems directly to AD using Samba Winbind

You need two components to connect a RHEL system to AD. One component, Samba Winbind, interacts with the AD identity and authentication source, and the other component, realmd, detects available domains and configures the underlying RHEL system services, in this case Samba Winbind, to connect to the AD domain.

This section describes using Samba Winbind to connect a RHEL system to Active Directory (AD).

2.1. Overview of direct integration using Samba Winbind

Samba Winbind emulates a Windows client on a Linux system and communicates with AD servers.

You can use the realmd service to configure Samba Winbind by:

  • Configuring network authentication and domain membership in a standard way.
  • Automatically discovering information about accessible domains and realms.
  • Not requiring advanced configuration to join a domain or realm.

Note that:

  • Direct integration with Winbind in a multi-forest AD setup requires bidirectional trusts.
  • Remote forests must trust the local forest to ensure that the idmap_ad plug-in handles remote forest users correctly.

Samba’s winbindd service provides an interface for the Name Service Switch (NSS) and enables domain users to authenticate to AD when logging into the local system.

Using winbindd provides the benefit that you can enhance the configuration to share directories and printers without installing additional software. For further detail, see the section about Using Samba as a server in the Deploying Different Types of Servers Guide.

Additional resources

  • See the realmd man page.
  • See the winbindd man page.

2.2. Supported Windows platforms for direct integration

You can directly integrate your RHEL system with Active Directory forests that use the following forest and domain functional levels:

  • Forest functional level range: Windows Server 2008 - Windows Server 2016
  • Domain functional level range: Windows Server 2008 - Windows Server 2016

Direct integration has been tested on the following supported operating systems:

  • Windows Server 2022 (RHEL 8.7 and above)
  • Windows Server 2019
  • Windows Server 2016
  • Windows Server 2012 R2

Windows Server 2019 and Windows Server 2022 do not introduce a new functional level. The highest functional level Windows Server 2019 and Windows Server 2022 use is Windows Server 2016.

2.3. Joining a RHEL system to an AD domain

Samba Winbind is an alternative to the System Security Services Daemon (SSSD) for connecting a Red Hat Enterprise Linux (RHEL) system with Active Directory (AD). You can join a RHEL system to an AD domain by using realmd to configure Samba Winbind.


  1. If your AD requires the deprecated RC4 encryption type for Kerberos authentication, enable support for these ciphers in RHEL:

    # update-crypto-policies --set DEFAULT:AD-SUPPORT
  2. Install the following packages:

    # yum install realmd oddjob-mkhomedir oddjob samba-winbind-clients \
           samba-winbind samba-common-tools samba-winbind-krb5-locator
  3. To share directories or printers on the domain member, install the samba package:

    # yum install samba
  4. Backup the existing /etc/samba/smb.conf Samba configuration file:

    # mv /etc/samba/smb.conf /etc/samba/smb.conf.bak
  5. Join the domain. For example, to join a domain named

    # realm join --membership-software=samba --client-software=winbind

    Using the previous command, the realm utility automatically:

    • Creates a /etc/samba/smb.conf file for a membership in the domain
    • Adds the winbind module for user and group lookups to the /etc/nsswitch.conf file
    • Updates the Pluggable Authentication Module (PAM) configuration files in the /etc/pam.d/ directory
    • Starts the winbind service and enables the service to start when the system boots
  6. Optionally, set an alternative ID mapping back end or customized ID mapping settings in the /etc/samba/smb.conf file. For details, see the Understanding and configuring Samba ID mapping
  7. Edit the /etc/krb5.conf file and add the following section:

        localauth = {
            module = winbind:/usr/lib64/samba/krb5/
            enable_only = winbind
  8. Verify that the winbind service is running:

    # systemctl status winbind
       Active: active (running) since Tue 2018-11-06 19:10:40 CET; 15s ago

    To enable Samba to query domain user and group information, the winbind service must be running before you start smb.

  9. If you installed the samba package to share directories and printers, enable and start the smb service:

    # systemctl enable --now smb

Verification steps

  1. Display an AD user’s details, such as the AD administrator account in the AD domain:

    # getent passwd "AD\administrator"
  2. Query the members of the domain users group in the AD domain:

    # getent group "AD\Domain Users"
        AD\domain users:x:10000:user1,user2
  3. Optionally, verify that you can use domain users and groups when you set permissions on files and directories. For example, to set the owner of the /srv/samba/example.txt file to AD\administrator and the group to AD\Domain Users:

    # chown "AD\administrator":"AD\Domain Users" /srv/samba/example.txt
  4. Verify that Kerberos authentication works as expected:

    1. On the AD domain member, obtain a ticket for the administrator@AD.EXAMPLE.COM principal:

      # kinit administrator@AD.EXAMPLE.COM
    2. Display the cached Kerberos ticket:

      # klist
      Ticket cache: KCM:0
      Default principal: administrator@AD.EXAMPLE.COM
      Valid starting       Expires              Service principal
      01.11.2018 10:00:00  01.11.2018 20:00:00  krbtgt/AD.EXAMPLE.COM@AD.EXAMPLE.COM
              renew until 08.11.2018 05:00:00
  5. Display the available domains:

    # wbinfo --all-domains

Additional resources

2.4. realm commands

The realmd system has two major task areas:

  • Managing system enrollment in a domain.
  • Controlling which domain users are allowed to access local system resources.

In realmd use the command line tool realm to run commands. Most realm commands require the user to specify the action that the utility should perform, and the entity, such as a domain or user account, for which to perform the action.

Table 2.1. realmd Commands


Realm Commands


Run a discovery scan for domains on the network.


Add the system to the specified domain.


Remove the system from the specified domain.


List all configured domains for the system or all discovered and configured domains.

Login Commands


Enable access for specific users or for all users within a configured domain to access the local system.


Restrict access for specific users or for all users within a configured domain to access the local system.

Additional resources

  • The realm(8) man page.