This is the first line in the Samba 3.0 release notes:

Active Directory support. Samba 3.0 is now able to
join a ADS(Active Directory Service) realm as a member
server and authenticate users using LDAP/Kerberos.

The intent of this article is to show you how to configure your Linux machine and Samba server to participate in a Windows 2000 Active Directory domain as a Member Server using Kerberos authentication. This involves using the security = ADS security mode in Samba.

Why would you want to do this? This eliminates the need to create separate Samba user accounts on your Linux server so your Windows users can access the Samba shares. Besides eliminating a lot of administrative overhead, without this, you would need to try to keep the password for the Samba user account synched with the password for the user in the AD domain. If you didn't and a Windows user changed his password, he would be prompted for a password every time he accessed a Samba share.

Probably the main advantage to the security = ADS security mode is if you are running a Win2k AD domain in native mode and your security policy prohibits the use of NT-compatible authentication protocols. All of your workstations would be Windows 2000 or XP Professional. In this case, Samba was not previously able to act as a Domain Member server in the domain.

If you want to be able to use winbind (discussed in another article), your Samba server MUST be a domain Member Server.

If you're not familiar with the different AD modes, here's a brief explanation. In mixed mode, all windows clients are able to authenticate to the domain including Win9x, NT4, Win2k, and XP Pro. Samba could also be a Member Server of this domain.
Active Directory in native mode perfectly allows NT4-style Domain Members. This is contrary to popular belief.

Active Directory in native mode prohibits only the use of Backup Domain Controllers running MS Windows NT4. Using AD in native mode and restricting the use of the NT-compatible authentication protocols (i.e., using Kerberos authentication), only Win2k and XP Pro clients can belong to the domain. If you have a network with just Win2k and XP Pro clients, this is the preferred and most secure mode.

The intended audience of this article are those who are already experienced with configuring Samba. It is assumed that the reader has sucessfully configured a Samba server in the past to integrate with a Windows domain or has a thorough understanding of how it is done. This would be using either the security = server or security = domain security modes. The reader would not need experience in configuring Samba to act as a Primary Domain Controller(PDC). This article is not intended for those who have never used Samba before. It should be obvious that having a working Windows 2000 AD domain is also a must.

The only version of Linux I've tried this on is Red Hat 9, so that's what this article is geared towards. It should work on any version of Linux though once you get Kerberos installed and working.


This is the setup on my network:

Red Hat 9 with Samba 2.2.8a installed from the RPM package from, not from the RH CDs.
host/NetBIOS name - delldim(
Samba server was set up using security = server and used the Win2k AD DC for authentication.

Win2k AD DC running SP4
Machine name - pe500sc(
Second Win2k AD DC named mainnt(
AD domain name -
Network domain name -
Running DNS for the entire network
Running WINS for the entire network


The most crucial thing you need to make this work is to have Kerberos V5 installed on your Linux machine. For Red Hat 9, the 2 rpm packages you need to have installed are krb5-libs and krb5-workstation. You should also install the krb5-server package so the documentation pages that are installed with this package are available. You will not need to configure your RH 9 machine as a Kerberos server, though.

You can check to see if they are already installed by using the rpm -q command:

rpm -q krb5-libs
rpm -q krb5-workstation
rpm -q krb5-server

These should return the version numbers, not error messages.

If you don't already have them installed, you can find them on the Red Hat 9 CD#2. You can install them from the command line using:

rpm -ivh

If you're not using Red Hat 9, you might find Kerberos on the installation CD's for your distribution. If your distribution uses RPM packages, try You can also go to for the latest release of Kerberos.

Once you get Kerberos installed on your Red Hat machine, there's a few critical things you need to check:

1. The time on your Win2k AD server and your Red Hat machine must match. The default Kerberos setting allows for a 5-minute discrepency. I reccomend setting them as close as possible to allow for drift over time. This is ABSOLUTELY CRITICAL! If the clocks don't match, it won't work.
This also applies to any other machine in your AD domain you want to authenticate to from your RH 9 machine using Kerberos.
2. Any user account in the Win2k AD domain you are going to use for authentication using Kerberos must have had the password changed at least once since it was created. If the password has never been changed since the account was created THIS WON'T WORK!!. On the accounts I used, I just changed the passwords, then changed them right back to their originals.

This is something that tripped me up until I found a small note about it in one of the HOWTOs. I had to change the password on both the administrator account and the user account I normally use so this would work.


Here's the steps to follow to install Samba 3.0:

1. Remove the old version of Samba from the computer with this command:

rpm -e samba

If you installed Samba from the RH CDs, you will probably have to remove more than one rpm package. You can use the RH 9 GUI package manager or execute:

rpm -qa | grep samba

to list the samba packages that are installed, then uninstall them from the command line.

You should uninstall your current version of Samba before installing Samba 3. When you remove Samba, the rpm command will back up your smb.conf file to smb.conf.rpmsave. I reccomend you make a back up copy of it yourself though.

If you're not using Red Hat 9, then use the method that is specific to your Linux distribution to uninstall Samba. If you installed Samba from source, see the documentation from to uninstall it.

2. Download and install Samba 3 rpm package for RH9.
Once it's downloaded from the site, just use:

rpm -ivh samba-3.0.0-1.i386.rpm

to install it.

If you're not using Red Hat 9, then use the method that is specific to your Linux distribution to install it. If you are installing Samba from source, see the documentation from to install it.

Once you install it, make the smb.conf.rpmsave file your active smb.conf file or restore your backup copy of smb.conf, then start Samba. Test it to be sure it works as it did before. Your Samba server should work the same with Samba 3 as it did with Samba 2.2.

Once you've tested Samba 3 to be sure it's working properly, it's CRITICAL that you stop it before you continue with further configuration. If you don't stop Samba, the following attempts to configure it will most likely fail.


If you're not familiar with Kerberos, there's a few things you can read to familiarize yourself with it:

The Red Hat 9 Linux Reference Guide, Chapter 17, Kerberos(part of the RH9 documentation set.
The files:
/usr/share/doc/krb5-server-1.2.7/admin.html, and install.html

If you're not using Red Hat, look for documentation that was installed when you installed Kerberos. You can also go to and get documentation there.

The most important thing in configuring Kerberos is the /etc/krb5.conf file. There should be an example one in /etc you can modify(that's what I did). If not, then just create one. Here's a copy of mine:

default = FILE:/var/log/krb5libs.log
kdc = FILE:/var/log/krb5kdc.log
admin_server = FILE:/var/log/kadmind.log

ticket_lifetime = 24000
default_realm = THE_COWANS.COM

kdc =
kdc =
admin_server =
default_domain =

[domain_realm] = THE_COWANS.COM = THE_COWANS.COM

profile = /var/kerberos/krb5kdc/kdc.conf

pam = {
debug = false
ticket_lifetime = 36000
renew_lifetime = 36000
forwardable = true
krb4_convert = false

All of the literature I read said the realm name should be in upper case but doesn't have to be. I took their recommendation.

As you can see, I named my realm the same as the AD Domain name. It just so happens that my AD Domain name is the same as my network domain name but that's not always the case.

Use your AD DC as the kdc(Key Distribution Center) in your file. You should also list it as the admin server. If you have more than one DC in your AD domain, you can list them as kdc entries.

Once you get your krb5.conf file done, you can test it with the kinit command. Execute:

kinit username@REALM

where username is the name of an account in your AD Domain. It should prompt you for a password. Enter the password for that user in the AD Domain. Note that you must enter the name of the realm in uppercase letters.

If it executes without error, then execute klist to see your Kerberos ticket.
Here are the commands I entered:

[rlcowan@delldim rlcowan]$ kinit rlcowan@THE_COWANS.COM
Password for rlcowan@THE_COWANS.COM:

[rlcowan@delldim rlcowan]$ klist
Ticket cache: FILE:/tmp/krb5cc_500
Default principal: rlcowan@THE_COWANS.COM

Valid starting Expires Service principal
09/28/03 15:35:40 09/29/03 01:35:40 krbtgt/THE_COWANS.COM@THE_COWANS.COM

Kerberos 4 ticket cache: /tmp/tkt500
klist: You have no tickets cached
[rlcowan@delldim rlcowan]$

If you get any error messages, make sure that:

- you have no spelling errors in your krb5.conf file
- the times are synched on your machines
- the password has been changed at least once on the username you are using.

Once you get a ticket from the AD DC, test it out by using Kerberos authentication with the smbclient command to view the shares on your Win2k AD DC:

smbclient -L /servername -k

That should return a list of all the shares on the DC.

Here's how the command worked on my machine:

[rlcowan@delldim rlcowan]$ smbclient -L /pe500sc -k

Sharename Type Comment
--------- ---- -------
photos Disk
D$ Disk Default share
rlcowan Disk
Savefile Disk
NETLOGON Disk Logon server share
Family Disk
ADMIN$ Disk Remote Admin
SYSVOL Disk Logon server share
Linux Disk
C$ Disk Default share

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

Workgroup Master
--------- -------
[rlcowan@delldim rlcowan]$

After you execute that, you should have another ticket for the server. You can view it with klist likethis:

[rlcowan@delldim rlcowan]$ klist
Ticket cache: FILE:/tmp/krb5cc_500
Default principal: rlcowan@THE_COWANS.COM

Valid starting Expires Service principal
09/28/03 15:35:40 09/29/03 01:35:40 krbtgt/THE_COWANS.COM@THE_COWANS.COM
09/28/03 15:42:13 09/29/03 01:35:40 pe500sc$@THE_COWANS.COM

Kerberos 4 ticket cache: /tmp/tkt500
klist: You have no tickets cached
[rlcowan@delldim rlcowan]$


When you install Samba from the rpm package, it will also install SWAT. Before you configure Samba, I suggest you fire up SWAT and read the document listed on the SWAT home page titled "The Samba HOWTO Collection" It has a section in it that deals with Win2k AD and Kerberos.

You now need to make the changes to your smb.conf file to enable Kerberos authentication and so you can join the AD domain. The important lines in smb.conf are:

realm = YOUR.REALM
security = ads
password server =

Here's a copy of my smb.conf file:

workgroup = the_cowans
netbios name = delldim
server string = Dell Dimension 8200
security = ads
password server =
encrypt passwords = yes

printcap name = /etc/printcap
load printers = yes
printing = cups

log file = /var/log/samba/%m.log
max log size = 0

socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192

local master = no
domain master = no
preferred master = no
wins server =
dns proxy = no

#============================ Share Definitions ==============================
path = /savefile
browseable = yes
writeable = yes
guest ok = no

comment = Home Directories
browseable = no
writable = yes
valid users = %S
create mode = 0664
directory mode = 0775

comment = All Printers
path = /var/spool/samba
browseable = yes
guest ok = yes
writable = no
printable = yes

Once you make the changes to smb.conf and before you start Samba, you need to join the AD domain. Before you do so there are two things that you should check:

- If there is a file named /etc/samba/secrets.tdb either delete, move or rename it. This file would be from your previous connections to the domain. A new one will be created when you join the domain.
- If there is an existing machine account in your AD domain for your Samba server, delete it. A new one will be created when you join the AD domain.

Here are the commands I used as root to join the AD domain:

kinit administrator@THE_COWANS.COM
net ads join -Uadministrator%password

The first command gets the Kerberos ticket you need to authenticate to the AD domain. You need to use the username of an account in your AD domain that has permission to join computers to the domain. The second command joins the domain.

If you're familiar with the command used with Samba 2.2 to join a domain, you'll notice the difference. smbpasswd is not used any more for this purpose.

If you successfully join the AD domain, you should receive a message stating that you successfully joined the Domain. You should also see a new /etc/samba/secrets.tdb file. There should also be a new machine account created in your Active Directory. If you look at the properties of the machine account, you should see that the OS is listed as Samba 3.0.

Once you've successfully joined the AD domain, start Samba in Red Hat using:

service smb start

or use whatever command you use with your distribution to start Samba.


You should now be able to access the shares on your Samba server from your Windows machines. In my case, I have XP Pro machines as clients. I can access the shares on my Red Hat 9, Samba 3 server without any problems. You can control access to the Linux file system or the Samba shares just as you did with Samba 2.2.

One advantage to using this type of authentication is that you don't need to create Samba accounts on the Linux server with the smbpasswd command. There is no need for the /etc/samba/smbpasswd file. You Windows users only need to be be concerned with one user account.

However, each user that accesses the Samba server will still need to have a valid Linux user account on the server that matches the account in the AD domain. The purpose of this account is to control access to the the Linux file system. The password for that account does not need to match the Win2k AD domain account password. The account doesn't even need to have the ability to log in locally to the Linux machine. It does have to exist however and it must have the proper permissions to the directories you are sharing out with Samba for the user to access them. This hasn't changed from Samba 2.2.

To get around the need for for local Linux accounts, you need to use winbind. It'll be interesting to see how that will work in conjuction with an AD domain. But that's the subject of another article.