Samba AD DC HOWTO

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Contents

Introduction

Since version 4.0, Samba can also act as a Domain Controller, that is compatible with Microsoft Active Directory. This document explains how to set up Samba as an Active Directory Domain Controller. It also is the start for upgrading an existing Samba NT4-style domain to Samba AD.

If you are upgrading an existing Samba Active Directory Domain Controller, please consult your distribution upgrade procedure or refer to the Updating Samba HowTo.

Even if the Domain Controller can act as a File Server as well, it's not a recommendation, to avoid issues around the Winbind internal to the Domain Controller. Also you should always consider to run more than one Domain Controller in your environment, for failover reasons.

While a Domain Controller is running our full file server, and can act quite well as a File Server, it is suggested that organisations run a distinct file server to allow upgrades of each without disrupting the other. It is also suggested that medium-sized sites should run more than one DC. And so it makes sense to have the DCs distinct to any file servers that may use the Domain Controllers. Also using distinct File Servers avoids many issues around the Winbindd internal to the Active Directory Domain Controller.

If you encounter any problems when using the HowTo, see the Samba AD DC Troubleshooting page.



Versions

Samba as an Active Directory Domain Controller requires at least version 4.0.0. But it's always recommended to use the latest version of Samba. It will contain fixes for bugs of previous releases and may contain improved Microsoft Active Directory compatibility and additional features. See the Samba Release Planning page for more details about the latest maintained versions and their Release Notes.



Server Information

Below, we will be using the following configuration/settings:

Installation Directory:            /usr/local/samba/

AD DC Hostname:                    DC1

AD DNS Domain Name:                samdom.example.com

Kerberos Realm:                    samdom.example.com

NT4 Domain Name/NetBIOS Name:      samdom

IP Address:                        192.168.1.1

Server Role:                       Domain Controller (DC)

Domain Admin Password:             pa$$w0rd

Forwarder DNS Server:              192.168.1.254



Installation

Different Ways To Install

Always check the OS Requirements for dependencies and recommendations.


You have a few options to install Samba:

  • Install binary distribution packages. Make sure, that you use a recent Samba installation with Active Directory Domain Controller capabilities!


Paths

Take care when running Samba commands, if you also have a previous version of Samba installed! To avoid inadvertently running the wrong version of a program, you should consider putting the „/usr/local/samba/bin/“ and „/usr/local/samba/sbin/“ directories at the beginning of your $PATH variable.


You can see what version of Samba and client tools, if any, is in your „$PATH“ variable by running:

# samba -V
# smbclient -V



Provisioning The Samba Active Directory

Note (Migration): If you plan to migrate an existing Samba NT4 domain to Samba AD, you have to skip this step! See the Samba Classic Upgrade HowTo, instead.

Note (Adding additional Domain Controllers): If you have already an Active Directory and only want to join a new, additional Samba Domain Controller, you have to skip this step! See the Join a domain as a DC HowTo, instead.


The provisioning creates an initial Active Directory database, when setting up the first Samba Domain Controller in a Domain. It must be executed with root privileges, to be able to write to the installation directory and set the correct permissions on files and folders.


Before you start the provisioning, make yourself familiar with the parameters and options of „samba-tool“:

# samba-tool domain provision --help 


Expecially the following two options are required, if your future Domain Controllers have multiple NICs. Because „samba-tool“ would auto-choose one of the IPv4/IPv6 addresses, if multiple where found, it might be necessary to bind Samba to the desired interfaces using

--option="interfaces=lo eth0" --option="bind interfaces only=yes"


Interactively provision a new domain (parameter explanation below):

# 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) [192.168.1.1]: 192.168.1.254
Administrator password: pa$$w0rd
Retype password: pa$$w0rd
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


Parameter explanations:


--use-rfc2307: Enables the NIS extensions, that allows to easily manage users/groups with the Windows tool Active Directory Users and Computers (ADUC), without manual counting UIDs/GIDs. It's recommented to enable this feature during the provisioning. Byside that it won't have any disadvantages if you don't use it, it may get a requirement in the future and prevent the necessity to manually do a Schema extension afterwards. For further information about RFC2307, see the Using RFC2307 on a Samba DC HowTo.


--interactive: Start the interactive provisioning. The values in squared brackets are defaults, that will be choose, if no input was made.


Realm: Kerberos Realm. It will be automatically used as Active Directory DNS domain name, too. The Realm has always to be in uppercase.


Domain: NT4/NetBIOS Domain Name. Usually the first part of the AD DNS domain name in uppercase.


Server Role: „dc“ for Domain Controller


DNS backend: You have to decide here, to use the Internal DNS server or BIND9 as DNS backend. The Internal DNS is default and the best choice for simple DNS requirements. It doesn't need any further actions. For complex DNS requirements, BIND9_DLZ is recommended. Don't use BIND9_FLATFILE! It's not documented and supported! See DNS Backend BIND for further information about using BIND. The DNS backend choice made during the provisioning isn't permanent. It can be changed afterwards.

A „DNS forwarder IP address“ is only prompted, if you had choosen the Internal DNS as backend. It defines the IP address of one DNS server, to which DNS queries should be forwarded, when your DNS server isn't authoritative. Commonly it is your providers DNS server IP address.

Note: You should always use a subdomain of your domain name (e. g. samdom.example.com). Never use your domain name (example.com) for your Active Directory DNS domain, to prevent problems accessing servers using that name (e. g. web server), but resolving to different IPs than your Domain Controllers!


Administrator password: The Domain Administrators password. It must meet the complex password requirements:

  • At least 8 characters
  • Containing three of the following four character groups
    • Uppercase letters
    • Lowercase letters
    • Numerals
    • Symbols (all keyboard characters not defined as letters or numerals)

If the password doesn't fulful the complexity requirements, the provisioning will fail and you have to start over (remove the „smb.conf“in that case).



Testing Your Samba Domain Controller

Note: If you are running any „smbd“, „nmbd“ or „winbindd“ processes from previous installations, they need to be stopped before starting „samba“ from your new installation!

To start the Samba Active Directory Domain Controller in „standard“ mode, which is suitable for production use, run

# samba


Samba doesn't yet have init scripts included. You can find examples on the Samba Init-Script page.


Run „smbclient“, to check if Samba provides the AD DC default shares „netlogon“ and „sysvol“ created in your „smb.conf“ during provisioning/upgrading:

$ smbclient -L localhost -U%
Domain=[SAMDOM] OS=[Unix] Server=[Samba 4.x.y]

        Sharename       Type      Comment
        ---------       ----      -------
        netlogon        Disk      
        sysvol          Disk      
        IPC$            IPC       IPC Service (Samba 4.x.y)
Domain=[SAMDOM] OS=[Unix] Server=[Samba 4.x.y]

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

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


To test that authentication is working, you should try to connect to the „netlogon“ share, using the Domain Administrator account, created during provisioning:

$ smbclient //localhost/netlogon -UAdministrator -c 'ls'
Enter Administrator's password: pa$$w0rd
Domain=[SAMDOM] OS=[Unix] Server=[Samba 4.x.y]
 .                                   D        0  Sat Jul  5 08:40:00 2014
 ..                                  D        0  Sat Jul  5 08:40:00 2014

               49386 blocks of size 524288. 42093 blocks available


If the tests fail, check out the Samba AD DC Troubleshooting page.



Configure DNS

A working DNS is essential to the correct operation of Active Directory. E. g. without the right DNS entries, Kerberos won't work, which in turn means that many of the basic features won't work! It is worth spending some extra time to ensure your DNS setup is correct, as debugging problems caused by misconfigured DNS can take a lot of time later.


DNS Backends

For additional information on the supported DNS backends and a decision aid, which fits best to your needs, see the DNS page.


Samba Internal DNS Server

Per default Samba uses its Internal DNS and no further configuration is required. The forwarder was already set during the provisioning and can be changed in your „smb.conf“ (reload of „samba“ is required after changes).


BIND9 DNS Backend

If you had choosen „BIND9_DLZ“ during your provisioning, see the Bind as DNS backend documentation for additional setup instructions.


Configure /etc/resolv.conf

Your Domain Controller requires a name server that knows your AD zone to resolve Active Directory DNS queries correctly. To accomplish this, you can add just your AD DCs IP and domain name to your „/etc/resolv.conf“:

domain samdom.example.com
nameserver 192.168.1.1

Note: If your server is set up to receive its IP configuration via DHCP, the „/etc/resolv.conf“ file might be automatically updated. Refer to your distributions documentation on how to stop/change this behavior, although DHCP is not recommended on a DC!

Testing DNS

To test that DNS is working properly, run the following commands and compare the output to what is shown:

$ host -t SRV _ldap._tcp.samdom.example.com.
_ldap._tcp.samdom.example.com has SRV record 0 100 389 dc1.samdom.example.com.
$ host -t SRV _kerberos._udp.samdom.example.com.
_kerberos._udp.samdom.example.com has SRV record 0 100 88 dc1.samdom.example.com.
$ host -t A dc1.samdom.example.com.
dc1.samdom.example.com has address 192.168.1.1


If you receive any errors, check your system logs to locate the problem.



Configure Kerberos

Kerberos is an important part of Active Directory. Typically the configuration is done in /etc/krb5.conf. During the provisioning, a working sample configuration was created. You can replace your krb5.conf file with the sample by copying or creating a symlink:

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


Testing Kerberos

Use „kinit“ to obtain a Kerberos ticket:

$ # kinit administrator@SAMDOM.EXAMPLE.COM
Password for administrator@SAMDOM.EXAMPLE.COM: 
Warning: Your password will expire in 41 days on Sat Aug 16 21:41:28 2014

Note: You must specify your realm in uppercase letters!

Note: Depending on your distribution, „kinit“ may just return you to a prompt, when successful.


To verify that Kerberos is working and that you had received a ticket, run:

$ klist
Ticket cache: FILE:/tmp/krb5cc_0
Default principal: administrator@SAMDOM.EXAMPLE.COM

Valid starting     Expires            Service principal
07/05/14 23:20:17  07/06/14 09:20:17  krbtgt/SAMDOM.EXAMPLE.COM@SAMDOM.EXAMPLE.COM
        renew until 07/06/14 23:20:15



Configure NTP

Note: NTP is optional, but highly recommended!

Active Directory requires an accurate time synchronization between all participant machines for Kerberos to work properly. It's highly recommended to use NTP or another form of time synchronization on your Domain Controller!

The Time Synchronisation documentation will provide all neccessary information for configuring NTP on Domain Controllers, Member Servers and clients.



Further Documentation

The Samba Wiki provides many useful documentation on administering your DC, (backup and recovery, setup and configure file shares, etc.), daily work (join a Windows client to a Domain, installing RSAT on Windows for AD Management, etc.) or authenticating other services against AD.


See the Samba Wiki user documentation for many further HowTos, tutorials and information.



Report Your Success/Failure!

We would encourage you to report your successes and failures to the samba mailing list on http://lists.samba.org.

Suggestions on improving the documentation are the same important, as reporting Bugs and complications.

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