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, @@ -12,7 +11,7 @@ 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 @@ -30,7 +29,7 @@ Domain membership has many advantages: MS Windows workstation users get the benefit of SSO

Domain user access rights and file ownership / access controls can be set - from the single Domain SAM (Security Accounts Management) database + from the single Domain SAM (Security Account Manager) database (works with Domain member servers as well as with MS Windows workstations that are domain members)

@@ -41,7 +40,7 @@ Domain membership has many advantages: Domain Member workstations can be better controlled through the use of Policy files (NTConfig.POL) and Desktop Profiles.

- Through the use of logon scripts users can be given transparent access to network + Through the use of logon scripts, users can be given transparent access to network applications that run off application servers

Network administrators gain better application and user access management @@ -49,7 +48,7 @@ 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, @@ -68,11 +67,11 @@ 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 @@ -92,8 +91,8 @@ 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 @@ -108,7 +107,7 @@ 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 @@ -140,11 +139,11 @@ 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. @@ -157,7 +156,7 @@ 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

Domain Member Server

+This mode of server operation involves the Samba machine being made a member of a domain security context. This means by definition that all user authentication will be done from a centrally defined authentication regime. The authentication regime may come from an NT3/4 style (old domain technology) @@ -259,30 +258,30 @@ Server, etc. Please refer to the Domain Control chapter 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 +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 @@ -292,11 +291,11 @@ 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 @@ -306,27 +305,28 @@ 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 +

+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.

As we are joining the domain DOM and the PDC for that domain (the only machine that has write access to the domain SAM database) -is DOMPDC. The Administrator%password is +is DOMPDC, we use it for the -S option. +The Administrator%password is the login name and password for an account which has the necessary privilege to add machines to the domain. If this is successful you will see the message: @@ -343,7 +343,7 @@ trust account on the PDC beforehand. This command goes through the machine account password change protocol, then writes the new (random) machine account password for this Samba server into a file in the same directory -in which an smbpasswd file would be stored - normally : +in which an smbpasswd file would be stored - normally:

/usr/local/samba/private/secrets.tdb

@@ -354,7 +354,7 @@ 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 @@ -365,8 +365,8 @@ filesystem. This is very similar to the older Samba security mode where Samba would pass through the authentication request to a Windows NT server in the same way as a Windows 95 or Windows 98 server would.

-Please refer to the Winbind -paper for information on a system to automatically +Please refer to the Winbind chapter +for information on a system to automatically assign UNIX uids and gids to Windows NT Domain users and groups.

The advantage to domain-level security is that the @@ -396,27 +396,27 @@ was first published in the Web magazine LinuxWorld as the article Doing 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. -

`Setup your smb.conf`

+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`

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:

 	[realms]
@@ -429,7 +429,7 @@ Test your config by doing a kinit
 making sure that your password is accepted by the Win2000 KDC.
 
Note

 The realm must be uppercase or you will get Cannot find KDC for
-requested realm while getting initial credentials error
+requested realm while getting initial credentials error.
 
Note

 Time between the two servers must be synchronized.  You will get a
 kinit(v5): Clock skew too great while getting initial credentials
@@ -437,70 +437,70 @@ if the time difference is more than five minutes.
 

 You also must ensure that you can do a reverse DNS lookup on the IP
 address of your KDC. Also, the name that this reverse lookup maps to
-must either be the netbios name of the KDC (ie. the hostname with no
-domain attached) or it can alternatively be the netbios name
+must either be the NetBIOS name of the KDC (ie. the hostname with no
+domain attached) or it can alternatively be the NetBIOS name
 followed by the realm. 
 

 The easiest way to ensure you get this right is to add a 
 /etc/hosts entry mapping the IP address of your KDC to 
-its netbios name. If you don't get this right then you will get a 
+its NetBIOS name. If you don't get this right then you will get a 
 local error when you try to join the realm.
 

-If all you want is kerberos support in smbclient then you can skip
+If all you want is Kerberos support in smbclient then you can skip
 straight to Test with smbclient now. 
 Creating a computer account 
 and testing your servers
-is only needed if you want kerberos support for smbd and winbindd.
-

`Create the computer account`

+is only needed if you want Kerberos support for smbd and winbindd. +

`Create the computer account`

As a user that has write permission on the Samba private directory (usually root) run: -

-	net join -U Administrator%password
-

-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. + + root# net join -U Administrator%password + + 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. +

`Test your server setup`

If the join was successful, you will see a new computer account with the NetBIOS name of your Samba server in Active Directory (in the "Computers" folder under Users and Computers.

On a Windows 2000 client try net use * \\server\share. You should -be logged in with kerberos without needing to know a password. If +be logged in with Kerberos without needing to know a password. If this fails then run klist tickets. Did you get a ticket for the server? Does it have an encoding type of DES-CBC-MD5 ?

`Testing with smbclient`

On your Samba server try to login to a Win2000 server or your Samba -server using smbclient and kerberos. Use smbclient as usual, but -specify the -k option to choose kerberos authentication. -

`Notes`

+server using smbclient and Kerberos. Use smbclient as usual, but +specify the -k option to choose Kerberos authentication. +

`Notes`

You must change administrator password at least once after DC install, to create the right encoding types

W2k doesn't seem to create the _kerberos._udp and _ldap._tcp in their defaults DNS setup. Maybe fixed in service packs? -

`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. +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 after repeated failed attempts to add a machine account that it is necessary to "re-install" 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 -exists on the network - I know it doen't. Why is this failing? +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