Setting up Samba as an Active Directory Domain Controller

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Introduction

Starting with version 4.0, Samba is able to run as an Active Directory (AD) domain controller (DC). If you are installing Samba in an production environment, it is recommended to run two or more DCs for failover reasons.

This documentation describes how to set up Samba as the first DC to build a new AD forest. Additionally, use this documentation if you are migrating a Samba NT4 domain to Samba AD. To join Samba as an additional DC to an existing AD forest, see Joining a Samba DC to an Existing Active Directory.

Samba as an AD DC only support:



Preparing the Installation

  • Select a DNS domain for your Active Directory (AD) forest. The name is additionally used as AD Kerberos realm.
For additional information, see Active Directory Naming FAQ.
  • Use a static IP address on the domain controller (DC).
  • Disable tools, such as resolvconf, that automatically update your /etc/resolv.conf DNS resolver configuration file. Active Directory (AD) DCs and domain members must use an DNS server that is able to resolve the AD DNS zones.
  • Verify that no Samba processes are running:
# ps ax | egrep "samba|smbd|nmbd|winbindd"
If the output lists any samba, smbd, nmbd, or winbindd processes, shut down the processes.
  • Verify that the /etc/hosts file on the DC correctly resolves the fully-qualified domain name (FQDN) and short host name to the LAN IP address of the DC. For example:
127.0.0.1     localhost.localdomain      localhost
10.99.0.1     DC1.samdom.example.com     DC1
The host name and FQDN must not resolve to the 127.0.0.1 IP address or any other IP address than the one used on the LAN interface of the DC.
  • If you run previously a Samba installation on this host:
  • Remove the existing smb.conf file. To list the path to the file:
# smbd -b | grep "CONFIGFILE"
   CONFIGFILE: /usr/local/samba/etc/samba/smb.conf
  • Remove all Samba database files, such as *.tdb and *.ldb files. To list the folders containing Samba databases:
# smbd -b | egrep "LOCKDIR|STATEDIR|CACHEDIR|PRIVATE_DIR"
  LOCKDIR: /usr/local/samba/var/lock/
  STATEDIR: /usr/local/samba/var/locks/
  CACHEDIR: /usr/local/samba/var/cache/
  PRIVATE_DIR: /usr/local/samba/private/
Starting with a clean environment helps you to prevent confusion and no files from your previous Samba installation are mixed with your new domain DC installation.



Installing Samba

For details, see Installing Samba.

If you built Samba, add the directories containing the Samba commands to your $PATH variable. For details, see Adding Samba Commands to the $PATH Variable




Provisioning a Samba Active Directory

The Samba Active Directory (AD) provisioning process creates the AD databases and adds initial records, such as the domain administrator account and required DNS entries.

If you are migrating a Samba NT4 domain to AD, skip this step and run the Samba classic upgrade. For details, see Migrating a Samba NT4 Domain to Samba AD (Classic Upgrade).


The samba-tool domain provision command provides several parameters to use with the interactive and non-interactive setup. For details, see:

# samba-tool domain provision --help



Parameter Explanation

You have to set the following parameters during the provisioning process:

Interactive Mode Setting Non-interactive Mode Parameter Explanation
--use-rfc2307 --use-rfc2307 Enables the NIS extensions.
Realm --realm Kerberos realm. This is also used as the AD DNS domain. For example: samdom.example.com.
Domain --domain NetBIOS domain name. Always use the first part of the AD DNS domain. For example: samdom.
Server Role --server-role Installs the domain controller DC role.
DNS backend --dns-backend Sets the DNS back end. The first DC in an AD must be installed using a DNS back end. Note that the BIND9_FLATFILE is not supported and removed in a future Samba version.
DNS forwarder IP address not available This setting is only available when using the SAMBA_INTERNAL DNS back end. For details, see Setting up a DNS Forwarder.
Administrator password --adminpass Sets the domain administrator password. If the password does not match the complexity requirements, the provisioning fails. For details, see Microsoft TechNet: Passwords must meet complexity requirements.

Other parameters frequently used with the samba-tool domain provision command:

  • --option="interfaces=lo eth0" --option="bind interfaces only=yes": If your server has multiple network interfaces, use these options to bind Samba to the specified interfaces. This enables the samba-tool command to register the correct LAN IP address in the directory during the join.


Provisioning Samba AD in Interactive Mode

To provision a Samba Active Directory (AD) interactively, run:

# samba-tool domain provision --use-rfc2307 --interactive
Realm [SAMDOM.EXAMPLE.COM]: SAMDOM.EXAMPLE.COM
 Domain [SAMDOM]: SAMDOM
 Server Role (dc, member, standalone) [dc]: dc
 DNS backend (SAMBA_INTERNAL, BIND9_FLATFILE, BIND9_DLZ, NONE) [SAMBA_INTERNAL]: SAMBA_INTERNAL
 DNS forwarder IP address (write 'none' to disable forwarding) [10.99.0.1]: 8.8.8.8
Administrator password: Passw0rd
Retype password: Passw0rd
Looking up IPv4 addresses
Looking up IPv6 addresses
No IPv6 address will be assigned
Setting up share.ldb
Setting up secrets.ldb
Setting up the registry
Setting up the privileges database
Setting up idmap db
Setting up SAM db
Setting up sam.ldb partitions and settings
Setting up sam.ldb rootDSE
Pre-loading the Samba 4 and AD schema
Adding DomainDN: DC=samdom,DC=example,DC=com
Adding configuration container
Setting up sam.ldb schema
Setting up sam.ldb configuration data
Setting up display specifiers
Modifying display specifiers
Adding users container                                                                                                                                                                                        
Modifying users container                                                                                                                                                                                     
Adding computers container                                                                                                                                                                                    
Modifying computers container                                                                                                                                                                                 
Setting up sam.ldb data                                                                                                                                                                                       
Setting up well known security principals                                                                                                                                                                     
Setting up sam.ldb users and groups                                                                                                                                                                           
Setting up self join                                                                                                                                                                                          
Adding DNS accounts                                                                                                                                                                                           
Creating CN=MicrosoftDNS,CN=System,DC=samdom,DC=example,DC=com                                                                                                                                                
Creating DomainDnsZones and ForestDnsZones partitions                                                                                                                                                         
Populating DomainDnsZones and ForestDnsZones partitions                                                                                                                                                       
Setting up sam.ldb rootDSE marking as synchronized                                                                                                                                                            
Fixing provision GUIDs                                                                                                                                                                                        
A Kerberos configuration suitable for Samba 4 has been generated at /usr/local/samba/private/krb5.conf                                                                                                        
Setting up fake yp server settings                                                                                                                                                                            
Once the above files are installed, your Samba4 server will be ready to use                                                                                                                                   
Server Role:           active directory domain controller                                                                                                                                                     
Hostname:              DC1                                                                                                                                                                                    
NetBIOS Domain:        SAMDOM                                                                                                                                                                                 
DNS Domain:            samdom.example.com                                                                                                                                                                     
DOMAIN SID:            S-1-5-21-2614513918-2685075268-614796884


Provisioning Samba AD in Non-interactive Mode

For example, to provision a Samba Active Directory (AD) non-interactively with the following settings:

  • Server role: dc
  • NIS extensions enabled
  • Internal DNS back end
  • Kerberos realm and AD DNS zone: samdom.example.com
  • NetBIOS domain name: SAMDOM
  • Domain administrator password: Passw0rd
# samba-tool domain provision --server-role=dc --use-rfc2307 --dns-backend=SAMBA_INTERNAL --realm=SAMDOM.EXAMPLE.COM --domain=SAMDOM --adminpass=Passw0rd



Setting up the AD DNS back end

Skip this step if you provisioned the domain controller (DC) using the SAMBA_INTERNAL DNS back end.

  • Start the BIND DNS server. For example:
# systemctl start named
For details how to start services, see you distribution's documentation.



Configuring the DNS Resolver

Domain members in an Active Directory (AD) use DNS to locate services, such as LDAP and Kerberos. For that, they need to use a DNS server, that is able to resolve the AD DNS zone.

On your domain controller (DC), set the AD DNS domain in the domain and the IP of your DC in the nameserver parameter of the /etc/resolv.conf file. For example:

domain samdom.example.com
nameserver 10.99.0.1



Configuring Kerberos

In an Active Directory (AD), Kerberos is used to authenticate users, machines, and services.

During the provisioning, Samba created a Kerberos configuration file for your domain controller (DC). To use, remove your existing /etc/krb5.conf file and create a symbolic link to the pre-configured Kerberos configuration:

# rm /etc/krb5.conf
# ln -sf /usr/local/samba/private/krb5.conf /etc/krb5.conf

The pre-created Kerberos configuration uses DNS service (SRV) resource records to locate the Kerberos distribution center (KDC).



Testing your Samba AD DC

To start the samba service manually, enter:

# samba

Samba does not provide System V init scripts, systemd, upstart, or other services configuration files.

  • If you installed Samba using packages, use the script or service configuration file included in the package to start Samba.
  • If you built Samba, see your distribution's documentation for how to create a script or configuration to start services. For user-created example System V init scripts, see Samba AD Init Script Examples.


Verifying the File Server

To list all shares provided by the domain controller (DC):

$ smbclient -L localhost -U%
Domain=[SAMDOM] OS=[Unix] Server=[Samba x.y.z]

        Sharename       Type      Comment
        ---------       ----      -------
        netlogon        Disk      
        sysvol          Disk      
        IPC$            IPC       IPC Service (Samba x.y.z)
Domain=[SAMDOM] OS=[Unix] Server=[Samba x.y.z]

        Server               Comment
        ---------            -------

        Workgroup            Master
        ---------            -------

To verify authentication, connect to the netlogon share using the domain administrator account:

$ smbclient //localhost/netlogon -UAdministrator -c 'ls'
Enter Administrator's password: 
Domain=[SAMDOM] OS=[Unix] Server=[Samba x.y.z]
 .                                   D        0  Tue Nov  1 08:40:00 2016
 ..                                  D        0  Tue Nov  1 08:40:00 2016

               49386 blocks of size 524288. 42093 blocks available

If one or more tests fail, see Troubleshooting.


Verifying DNS

To verify that your Active Directory (AD) DNS configuration works correctly, query some DNS records:

  • The tcp-based _ldap service (SRV) resource record in the domain:
$ host -t SRV _ldap._tcp.samdom.example.com.
_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com.
  • The udp-based _kerberos SRV resource record in the domain:
$ host -t SRV _kerberos._udp.samdom.example.com.
_kerberos._udp.samdom.example.com has SRV record 0 100 88 dc1.samdom.example.com.
  • The A record of the domain controller:
$ host -t A dc1.samdom.example.com.
dc1.samdom.example.com has address 10.99.0.1

If one or more tests fail, see Troubleshooting.


Verifying Kerberos

  • Request a Kerberos ticket for the domain administrator account:
$ kinit administrator
Password for administrator@SAMDOM.EXAMPLE.COM:
  • List the cached Kerberos tickets:
$ klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: administrator@SAMDOM.EXAMPLE.COM

Valid starting       Expires              Service principal
01.11.2016 08:45:00  12.11.2016 18:45:00  krbtgt/SAMDOM.EXAMPLE.COM@SAMDOM.EXAMPLE.COM
	renew until 02.11.2016 08:44:59

If you one or more tests fail, see Troubleshooting.



Configuring Time Synchronisation

Kerberos requires a synchronised time on all domain members. For further details and how to set up the ntpd service, see Time Synchronisation.



Using the Domain Controller as a File Server

The Samba Active Directory (AD) domain controller (DC) is able to provide file shares, such as all other installation modes. However, the Samba team does not recommend to use a DC as file server because the DC smbd process has some limitations compared with the service in non-DC setups. For example, the auto-enabled acl_xattr virtual file system (VFS) object enables you only to configure shares with Windows access control lists (ACL). Running shares with POSIX ACLs on a Samba DC is not supported. To provide network shares with the full capabilities of Samba, set up a Samba domain member with file shares. For details, see:

If you do not want to follow the Samba team's recommendation and use the DC additionally as a file server, configure libnss_winbind before you start setting up shares. For details, see libsss_winbind.



Troubleshooting

For further details, see Samba AD DC Troubleshooting.



Further Samba-related Documentation

See User Documentation.