Chapter 7. Domain Membership

Domain Membership is a subject of vital concern, Samba must be able to participate as a member server in a Microsoft Domain security context, and Samba must be capable of providing Domain machine member trust accounts, @@ -11,7 +12,7 @@ within the current MS Windows networking world and particularly in the Unix/Linux networking and administration world, a considerable level of mis-information, incorrect understanding, and a lack of knowledge. Hopefully this chapter will fill the voids. -

Features and Benefits

MS Windows workstations and servers that want to participate in domain security need to be made Domain members. Participating in Domain security is often called @@ -48,7 +49,7 @@ Domain membership has many advantages: client or server, other than the central Domain database (either NT4/Samba SAM style Domain, NT4 Domain that is back ended with an LDAP directory, or via an Active Directory infrastructure) -

MS Windows Workstation/Server Machine Trust Accounts

A machine trust account is an account that is used to authenticate a client machine (rather than a user) to the Domain Controller server. In Windows terminology, @@ -67,11 +68,11 @@ shared secret with the domain controller. A Windows NT4 PDC stores each machine trust account in the Windows Registry. The introduction of MS Windows 2000 saw the introduction of Active Directory, the new repository for machine trust accounts. -

A Samba PDC, however, stores each machine trust account in two parts, as follows: -

+
- A Domain Security Account (stored in the passdb backend that has been configured in the smb.conf file. The precise nature of the account information that is @@ -91,8 +92,8 @@ as follows: /etc/passwd. Work is in progress to allow a simplified mode of operation that does not require Unix user accounts, but this may not be a feature of the early releases of Samba-3. -
-
+

There are three ways to create machine trust accounts:

Manual creation from the Unix/Linux command line. Here, both the Samba and @@ -107,7 +108,7 @@ There are three ways to create machine trust accounts: created by Samba at the time the client is joined to the domain. (For security, this is the recommended method.) The corresponding Unix account may be created automatically or manually. -

Manual Creation of Machine Trust Accounts

The first step in manually creating a machine trust account is to manually create the corresponding Unix account in /etc/passwd. This can be done using vipw or another 'add user' command @@ -139,11 +140,11 @@ Now that the corresponding Unix account has been created, the next step is to cr the Samba account for the client containing the well-known initial machine trust account password. This can be done using the smbpasswd(8) command as shown here: -

 root# smbpasswd -a -m machine_name
-

where machine_name is the machine's NetBIOS name. The RID of the new machine account is generated from the UID of the corresponding Unix account. @@ -156,7 +157,7 @@ the corresponding Unix account. your domain using a machine with the same NetBIOS name. A PDC inherently trusts members of the domain and will serve out a large degree of user information to such clients. You have been warned! -

Using NT4 Server Manager to Add Machine Accounts to the Domain

Making an MS Windows Workstation or Server a Domain Member

The procedure for making an MS Windows workstation of server a member of the domain varies with the version of Windows: -

Windows 200x XP Professional

When the user elects to make the client a domain member, Windows 200x prompts for an account and password that has privileges to create machine accounts in the domain. A Samba administrative account (i.e., a Samba account that has root privileges on the @@ -225,7 +226,7 @@ with the version of Windows: encryption key for setting the password of the machine trust account. The machine trust account will be created on-the-fly, or updated if it already exists. -

Windows NT4

If the machine trust account was created manually, on the Identification Changes menu enter the domain name, but do not check the box Create a Computer Account in the Domain. @@ -238,7 +239,7 @@ with the version of Windows: Domain. In this case, joining the domain proceeds as above for Windows 2000 (i.e., you must supply a Samba administrative account when prompted). -

Samba

Joining a Samba client to a domain is documented in +

Samba

Joining a Samba client to a domain is documented in the Domain Member Server section of this chapter chapter.

Domain Member Server

This mode of server operation involves the Samba machine being made a member @@ -260,28 +261,28 @@ for more information regarding how to create a domain machine account for a domain member server as well as for information regarding how to enable the Samba domain member machine to join the domain and to be fully trusted by it. -

Joining an NT4 type Domain with Samba-3

Table 7.1. Assumptions

NetBIOS name:	SERV1
Win2K/NT domain name:	DOM
Domain's PDC NetBIOS name:	DOMPDC
Domain's BDC NetBIOS names:	DOMBDC1 and DOMBDC2

Joining an NT4 type Domain with Samba-3

Table 7.1. Assumptions

NetBIOS name:	SERV1
Win2K/NT domain name:	DOM
Domain's PDC NetBIOS name:	DOMPDC
Domain's BDC NetBIOS names:	DOMBDC1 and DOMBDC2

First, you must edit your smb.conf file to tell Samba it should now use domain security.

Change (or add) your security line in the [global] section of your smb.conf to read: -

+

+ security = domain
-

-

+

Next change the workgroup line in the [global] section to read: -

+

+ workgroup = DOM
-

-

+

as this is the name of the domain we are joining.

You must also have the parameter @@ -291,11 +292,11 @@ You must also have the parameter password server line in the [global] section to read: -

 password server = DOMPDC DOMBDC1 DOMBDC2
-

These are the primary and backup domain controllers Samba will attempt to contact in order to authenticate users. Samba will try to contact each of these servers in order, so you may want to @@ -305,21 +306,21 @@ among domain controllers. Alternatively, if you want smbd to automatically determine the list of Domain controllers to use for authentication, you may set this line to be: -

+

+ password server = *
-

-

+

This method allows Samba to use exactly the same mechanism that NT does. This method either broadcasts or uses a WINS database in order to find domain controllers to authenticate against.

In order to actually join the domain, you must run this command: -

 root# net join -S DOMPDC -UAdministrator%password
-

If the -S DOMPDC argument is not given then the domain name will be obtained from smb.conf.

@@ -354,7 +355,7 @@ as a shadow password file.

Finally, restart your Samba daemons and get ready for clients to begin using domain security! -

Why is this better than security = server?

Currently, domain security in Samba doesn't free you from having to create local Unix users to represent the users attaching to your server. This means that if domain user DOM\fred @@ -398,27 +399,30 @@ the NIS/NT Samba.

`Samba ADS Domain Membership`

This is a rough guide to setting up Samba 3.0 with Kerberos authentication against a Windows2000 KDC. A familiarity with Kerberos is assumed. -

`Setup your smb.conf`

+

`Setup your smb.conf`

You must use at least the following 3 options in smb.conf:

 	realm = your.kerberos.REALM
 	security = ADS
 	encrypt passwords = yes
-

+ In case samba can't figure out your ads server using your realm name, use the ads server option in smb.conf: -

+ 	ads server = your.kerberos.server
-

-
Note

+

+Note You do not need a smbpasswd file, and older clients will be authenticated as if security = domain, although it won't do any harm and allows you to have local users not in the domain. It is expected that the above required options will change soon when active directory integration will get better. -

`Setup your /etc/krb5.conf`

+

`Setup your /etc/krb5.conf`

The minimal configuration for krb5.conf is:

+        [libdefaults]
+            default_realm = YOUR.KERBEROS.REALM
+
 	[realms]
 	    YOUR.KERBEROS.REALM = {
 		kdc = your.kerberos.server
@@ -451,20 +455,20 @@ straight to Creating a computer account 
 and testing your servers
 is only needed if you want Kerberos support for smbd and winbindd.
-

`Create the computer account`

+

`Create the computer account`

As a user that has write permission on the Samba private directory (usually root) run: - + root# net join -U Administrator%password - - Possible errors - ADS support not compiled in Samba must be reconfigured (remove config.cache) and recompiled + +Possible errors +ADS support not compiled in Samba must be reconfigured (remove config.cache) and recompiled (make clean all install) after the Kerberos libs and headers are installed. net join prompts for user name You need to login to the domain using kinit USERNAME@REALM. USERNAME must be a user who has rights to add a machine - to the domain. -

`Test your server setup`

+ to the domain.

+

`Common Errors`

In the process of adding / deleting / re-adding domain member machine accounts there are many traps for the unwary player and there are many “little” things that can go wrong. It is particularly interesting how often subscribers on the samba mailing list have concluded @@ -491,7 +495,7 @@ after repeated failed attempts to add a machine account that it is necessary to MS Windows on t he machine. In truth, it is seldom necessary to reinstall because of this type of problem. The real solution is often very simple, and with understanding of how MS Windows networking functions. easily overcome. -

`Can Not Add Machine Back to Domain`

+

`Can Not Add Machine Back to Domain`

Problem: A Windows workstation was reinstalled. The original domain machine account was deleted and added immediately. The workstation will not join the domain if I use the same machine name. Attempts to add the machine fail with a message that the machine already @@ -500,7 +504,7 @@ exists on the network - I know it doesn't. Why is this failing? The original name is still in the NetBIOS name cache and must expire after machine account deletion BEFORE adding that same name as a domain member again. The best advice is to delete the old account and then to add the machine with a new name. -

`Adding Machine to Domain Fails`

+

`Adding Machine to Domain Fails`

Adding a Windows 200x or XP Professional machine to the Samba PDC Domain fails with a message that, The machine could not be added at this time, there is a network problem. Please try again later. Why? -- cgit