Chapter 11. Account Information Databases

Samba-3 implements a new capability to work concurrently with multiple account backends. The possible new combinations of password backends allows Samba-3 a degree of flexibility and scalability that previously could be achieved only with MS Windows Active Directory. @@ -16,7 +17,7 @@ deliver this functionality until a better method of recognising NT Group SIDs fr SIDs could be found. This feature may thus return during the life cycle for the Samba-3 series.

Note

Samba-3.0.0 does NOT support Non-Unix Account (NUA) operation. -

Features and Benefits

Samba-3 provides for complete backwards compatibility with Samba-2.2.x functionality as follows:

Backwards Compatibility Backends

Plain Text:: @@ -93,7 +94,7 @@ Samba-3 introduces the following new password backend capabilities:
nisplussam:: The NIS+ based passdb backend. Takes name NIS domain as an optional argument. Only works with Sun NIS+ servers. -

Technical Information

Old windows clients send plain text passwords over the wire. Samba can check these passwords by crypting them and comparing them to the hash stored in the unix user database.

@@ -111,7 +112,7 @@ Samba-3 introduces the following new password backend capabilities: information using a passdb backend. Commonly available backends are LDAP, plain text file, MySQL and nisplus. For more information, see the man page for smb.conf regarding the passdb backend parameter. -

Important Notes About Security

The unix and SMB password encryption techniques seem similar on the surface. This similarity is, however, only skin deep. The unix scheme typically sends clear text passwords over the network when logging in. This is bad. The SMB encryption scheme @@ -153,7 +154,7 @@ Samba-3 introduces the following new password backend capabilities: (broken) only the cached (encrypted) password will be sent to the resource server to affect a auto-reconnect. If the resource server does not support encrypted passwords the auto-reconnect will fail. USE OF ENCRYPTED PASSWORDS IS STRONGLY ADVISED. -

Advantages of Encrypted Passwords

Plain text passwords are not passed across +
Advantages of Encrypted Passwords
- Plain text passwords are not passed across the network. Someone using a network sniffer cannot just record passwords going to the SMB server.
- Plain text passwords are not stored anywhere in memory or on disk.
- WinNT doesn't like talking to a server @@ -164,11 +165,11 @@ Samba-3 introduces the following new password backend capabilities: only things you can do to stop this is to use SMB encryption.
- Encrypted password support allows automatic share (resource) reconnects.
- Encrypted passwords are essential for PDC/BDC - operation.
Advantages of non-encrypted passwords
- Plain text passwords are not kept + operation.
Advantages of non-encrypted passwords
- Plain text passwords are not kept on disk, and are NOT cached in memory.
- Uses same password file as other unix services such as login and ftp
- Use of other services (such as telnet and ftp) which send plain text passwords over the net, so sending them for SMB - isn't such a big deal.

Mapping User Identifiers between MS Windows and Unix

+ isn't such a big deal.

Mapping User Identifiers between MS Windows and Unix

Every operation in Unix/Linux requires a user identifier (UID), just as in MS Windows NT4 / 200x this requires a Security Identifier (SID). Samba provides two means for mapping an MS Windows user to a Unix/Linux UID. @@ -183,13 +184,13 @@ Samba-3 introduces the following new password backend capabilities: idmap uid, idmap gid parameters in smb.conf. Please refer to the man page for information about these parameters. These parameters are essential when mapping users from a remote SAM server. -

Account Management Tools

Samba-3 provides two (2) tools for management of User and machine accounts. These tools are called smbpasswd and pdbedit. A third tool is under development but is NOT expected to ship in time for Samba-3.0.0. The new tool will be a TCL/TK GUI tool that looks much like the MS Windows NT4 Domain User Manager - hopefully this will be announced in time for the Samba-3.0.1 release. -

The smbpasswd Command

The smbpasswd utility is a utility similar to the passwd or yppasswd programs. It maintains the two 32 byte password fields in the passdb backend. @@ -205,18 +206,18 @@ be announced in time for the Samba-3.0.1 release. smbpasswd can be used to:

add user or machine accounts

delete user or machine accounts

enable user or machine accounts

disable user or machine accounts

set to NULL user passwords

manage interdomain trust accounts

To run smbpasswd as a normal user just type: -

 		$ smbpasswd
 		Old SMB password: secret
-

For secret type old value here - or hit return if there was no old password -

 		New SMB Password: new secret
 		Repeat New SMB Password: new secret
-

If the old value does not match the current value stored for that user, or the two new values do not match each other, then the password will not be changed.

@@ -235,7 +236,7 @@ be announced in time for the Samba-3.0.1 release.

For more details on using smbpasswd refer to the man page (the definitive reference). -

The pdbedit Command

pdbedit is a tool that can be used only by root. It is used to manage the passdb backend. pdbedit can be used to:

add, remove or modify user accounts

listing user accounts

migrate user accounts

@@ -271,27 +272,27 @@ be announced in time for the Samba-3.0.1 release. Password last set: Sat, 14 Dec 2002 14:37:03 GMT Password can change: Sat, 14 Dec 2002 14:37:03 GMT Password must change: Mon, 18 Jan 2038 20:14:07 GMT -

Password Backends

Samba-3 offers the greatest flexibility in backend account database design of any SMB/CIFS server technology available today. The flexibility is immediately obvious as one begins to explore this capability.

It is possible to specify not only multiple different password backends, but even multiple backends of the same type. For example, to use two different tdbsam databases: -

 [globals]
 		passdb backend = tdbsam:/etc/samba/passdb.tdb, \
 		tdbsam:/etc/samba/old-passdb.tdb, guest
-

Plain Text

Older versions of Samba retrieved user information from the unix user database and eventually some other fields from the file /etc/samba/smbpasswd or /etc/smbpasswd. When password encryption is disabled, no SMB specific data is stored at all. Instead all operations are conducted via the way that the Samba host OS will access its /etc/passwd database. eg: On Linux systems that is done via PAM. -

smbpasswd - Encrypted Password Database

Traditionally, when configuring encrypt passwords = yes in Samba's smb.conf file, user account information such as username, LM/NT password hashes, password change times, and account @@ -322,7 +323,7 @@ backends of the same type. For example, to use two different tdbsam databases: Samba-3 provides an enhanced set of passdb backends that overcome the deficiencies of the smbpasswd plain text database. These are tdbsam, ldapsam, and xmlsam. Of these ldapsam will be of most interest to large corporate or enterprise sites. -

tdbsam

Samba can store user and machine account data in a "TDB" (Trivial Database). +

tdbsam

Samba can store user and machine account data in a "TDB" (Trivial Database). Using this backend doesn't require any additional configuration. This backend is recommended for new installations that do not require LDAP.

@@ -330,7 +331,7 @@ backends of the same type. For example, to use two different tdbsam databases: that have 250 or more users. Additionally, tdbsam is not capable of scaling for use in sites that require PDB/BDC implementations that requires replication of the account database. Clearly, for reason of scalability, the use of ldapsam should be encouraged. -

ldapsam

There are a few points to stress that the ldapsam does not provide. The LDAP support referred to in the this documentation does not include:

A means of retrieving user account information from @@ -358,16 +359,16 @@ backends of the same type. For example, to use two different tdbsam databases:
- The Samba-PDC-LDAP-HOWTO maintained by Ignacio Coupeau.
- The NT migration scripts from IDEALX that are geared to manage users and group in such a Samba-LDAP Domain Controller configuration. -
Supported LDAP Servers
+

Supported LDAP Servers

The LDAP ldapsam code has been developed and tested using the OpenLDAP 2.0 and 2.1 server and client libraries. The same code should work with Netscape's Directory Server and client SDK. However, there are bound to be compile errors and bugs. These should not be hard to fix. Please submit fixes via Bug reporting facility. -

Schema and Relationship to the RFC 2307 posixAccount

Samba 3.0 includes the necessary schema file for OpenLDAP 2.0 in examples/LDAP/samba.schema. The sambaSamAccount objectclass is given here: -

+			

+ objectclass ( 1.3.6.1.4.1.7165.2.2.3 NAME 'sambaSamAccount' SUP top AUXILIARY
     DESC 'Samba Auxiliary Account'
     MUST ( uid $ rid )
@@ -375,8 +376,8 @@ objectclass ( 1.3.6.1.4.1.7165.2.2.3 NAME 'sambaSamAccount' SUP top AUXILIARY
            logoffTime $ kickoffTime $ pwdCanChange $ pwdMustChange $ acctFlags $
            displayName $ smbHome $ homeDrive $ scriptPath $ profilePath $
            description $ userWorkstations $ primaryGroupID $ domain ))
-

-

+

The samba.schema file has been formatted for OpenLDAP 2.0/2.1. The OID's are owned by the Samba Team and as such is legal to be openly published. If you translate the schema to be used with Netscape DS, please @@ -398,23 +399,23 @@ objectclass ( 1.3.6.1.4.1.7165.2.2.3 NAME 'sambaSamAccount' SUP top AUXILIARY and functioning correctly. This division of information makes it possible to store all Samba account information in LDAP, but still maintain UNIX account information in NIS while the network is transitioning to a full LDAP infrastructure. -

OpenLDAP configuration

To include support for the sambaSamAccount object in an OpenLDAP directory server, first copy the samba.schema file to slapd's configuration directory. The samba.schema file can be found in the directory examples/LDAP in the samba source distribution. -

 root# cp samba.schema /etc/openldap/schema/
-

Next, include the samba.schema file in slapd.conf. The sambaSamAccount object contains two attributes which depend upon other schema files. The 'uid' attribute is defined in cosine.schema and the 'displayName' attribute is defined in the inetorgperson.schema file. Both of these must be included before the samba.schema file. -

+			

+ ## /etc/openldap/slapd.conf
 
 ## schema files (core.schema is required by default)
@@ -426,13 +427,13 @@ include            /etc/openldap/schema/inetorgperson.schema
 include            /etc/openldap/schema/samba.schema
 include            /etc/openldap/schema/nis.schema
 ....
-

-

+

It is recommended that you maintain some indices on some of the most useful attributes, like in the following example, to speed up searches made on sambaSamAccount objectclasses (and possibly posixAccount and posixGroup as well). -

+		

+ # Indices to maintain
 ## required by OpenLDAP
 index objectclass             eq
@@ -454,25 +455,25 @@ index   sambaSID              eq
 index   sambaPrimaryGroupSID  eq
 index   sambaDomainName       eq
 index   default               sub
-

-

+

Create the new index by executing: -

 ./sbin/slapindex -f slapd.conf
-

Remember to restart slapd after making these changes: -

 root# /etc/init.d/slapd restart
-

Initialise the LDAP database

+ +

Initialise the LDAP database

Before you can add accounts to the LDAP database you must create the account containers that they will be stored in. The following LDIF file should be modified to match your needs (ie: Your DNS entries, etc.). -

+		

+ # Organization for Samba Base
 dn: dc=plainjoe,dc=org
 objectclass: dcObject
@@ -500,26 +501,26 @@ objectclass: top
 objectclass: organizationalRole
 objectclass: simpleSecurityObject
 userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz
-

-

+

The userPassword shown above should be generated using slappasswd.

The following command will then load the contents of the LDIF file into the LDAP database. -

 $ slapadd -v -l initldap.dif
-

Do not forget to secure your LDAP server with an adequate access control list, as well as an admin password. -

Note

Before Samba can access the LDAP server you need to store the LDAP admin password into the Samba-3 secrets.tdb database by: -

 root#  smbpasswd -w secret
-

Configuring Samba

+ +

Configuring Samba

The following parameters are available in smb.conf only if your version of samba was built with LDAP support. Samba automatically builds with LDAP support if the LDAP libraries are found. @@ -527,8 +528,8 @@ userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz These are described in the smb.conf man page and so will not be repeated here. However, a sample smb.conf file for use with an LDAP directory could appear as -

+			

+ ## /usr/local/samba/lib/smb.conf
 [global]
      security = user
@@ -570,8 +571,8 @@ userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz
 
      # generally the default ldap search filter is ok
      # ldap filter = "(&(uid=%u)(objectclass=sambaSamAccount))"
-

-

Accounts and Groups management

+ +

Accounts and Groups management

As users accounts are managed through the sambaSamAccount objectclass, you should modify your existing administration tools to deal with sambaSamAccount attributes.

@@ -587,7 +588,7 @@ userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz groups. This means that Samba makes use of the posixGroup objectclass. For now, there is no NT-like group system management (global and local groups). -

Security and sambaSamAccount

There are two important points to remember when discussing the security of sambaSamAccount entries in the directory.

Never retrieve the lmPassword or @@ -613,17 +614,17 @@ userPassword: {SSHA}c3ZM9tBaBo9autm1dL3waDS21+JSfQVz The second security precaution is to prevent non-administrative users from harvesting password hashes from the directory. This can be done using the following ACL in slapd.conf: -

+			

+ ## allow the "ldap admin dn" access, but deny everyone else
 access to attrs=lmPassword,ntPassword
      by dn="cn=Samba Admin,ou=people,dc=plainjoe,dc=org" write
      by * none
-

-

LDAP special attributes for sambaSamAccounts

+ +

LDAP special attributes for sambaSamAccounts

The sambaSamAccount objectclass is composed of the following attributes: -

Table 11.1. Attributes in the sambaSamAccount objectclass (LDAP)

lmPassword

the LANMAN password 16-byte hash stored as a character +

Table 11.1. Attributes in the sambaSamAccount objectclass (LDAP)

`lmPassword`	the LANMAN password 16-byte hash stored as a character representation of a hexadecimal string.
`ntPassword`	the NT password hash 16-byte stored as a character representation of a hexadecimal string.
`pwdLastSet`	The integer time in seconds since 1970 when the `lmPassword` and `ntPassword` attributes were last set. @@ -646,8 +647,8 @@ access to attrs=lmPassword,ntPassword
`userWorkstation`	character string value currently unused.
`rid`	the integer representation of the user's relative identifier (RID).
`primaryGroupID`	the relative identifier (RID) of the primary group - of the user.
`domain`	domain the user is part of.

+ of the user.

domain domain the user is part of.

The majority of these parameters are only used when Samba is acting as a PDC of a domain (refer to the Samba as a primary domain controller chapter for details on how to configure Samba as a Primary Domain Controller). The following four attributes @@ -663,10 +664,10 @@ access to attrs=lmPassword,ntPassword of the logon home parameter is used in its place. Samba will only write the attribute value to the directory entry if the value is something other than the default (e.g. \\MOBY\becky). -

Example LDIF Entries for a sambaSamAccount

The following is a working LDIF with the inclusion of the posixAccount objectclass: -

+			

+	 	dn: uid=guest2, ou=people,dc=plainjoe,dc=org
 	ntPassword: 878D8014606CDA29677A44EFA1353FC7
 	pwdMustChange: 2147483647
@@ -681,12 +682,12 @@ access to attrs=lmPassword,ntPassword
 	logoffTime: 2147483647
 	rid: 19006
 	pwdCanChange: 0
-	

-	

+

The following is an LDIF entry for using both the sambaSamAccount and posixAccount objectclasses: -

+			

+	 	dn: uid=gcarter, ou=people,dc=plainjoe,dc=org
 	logonTime: 0
 	displayName: Gerald Carter
@@ -709,53 +710,53 @@ access to attrs=lmPassword,ntPassword
 	pwdCanChange: 0
 	pwdMustChange: 2147483647
 	ntPassword: 878D8014606CDA29677A44EFA1353FC7
-

-

Password synchronisation

+ +

Password synchronisation

Since version 3.0 samba can update the non-samba (LDAP) password stored with an account. When using pam_ldap, this allows changing both unix and windows passwords at once.

The ldap passwd sync options can have the following values:

yes: When the user changes his password, update ntPassword, lmPassword and the password fields.
no: Only update ntPassword and lmPassword.
only: Only update the LDAP password and let the LDAP server worry about the other fields. This option is only available when the LDAP server supports LDAP_EXOP_X_MODIFY_PASSWD.

More information can be found in the smb.conf manpage. -

MySQL

Every so often someone will come along with a great new idea. Storing of user accounts in an SQL backend is one of them. Those who want to do this are in the best position to know what the specific benefits are to them. This may sound like a cop-out, but in truth we can not attempt to document every nitty little detail why certain things of marginal utility to the bulk of Samba users might make sense to the rest. In any case, the following instructions should help the determined SQL user to implement a working system. -

Creating the database

You either can set up your own table and specify the field names to pdb_mysql (see below for the column names) or use the default table. The file examples/pdb/mysql/mysql.dump contains the correct queries to create the required tables. Use the command : -

$ mysql -uusername -hhostname -ppassword \
-databasename < /path/to/samba/examples/pdb/mysql/mysql.dump

Configuring

This plugin lacks some good documentation, but here is some short info:

Add a the following to the passdb backend variable in your smb.conf: -

+			$ mysql -uusername -hhostname -ppassword \
+databasename < /path/to/samba/examples/pdb/mysql/mysql.dump

+

Configuring

This plugin lacks some good documentation, but here is some short info:

Add a the following to the passdb backend variable in your smb.conf: +

 			passdb backend = [other-plugins] mysql:identifier [other-plugins]
-

The identifier can be any string you like, as long as it doesn't collide with + +

The identifier can be any string you like, as long as it doesn't collide with the identifiers of other plugins or other instances of pdb_mysql. If you specify multiple pdb_mysql.so entries in passdb backend, you also need to use different identifiers!

Additional options can be given through the smb.conf file in the [global] section. -

Table 11.2. Basic smb.conf options for MySQL passdb backend

Field	Contents
identifier:mysql host	host name, defaults to 'localhost'
identifier:mysql password
identifier:mysql user	defaults to 'samba'
identifier:mysql database	defaults to 'samba'
identifier:mysql port	defaults to 3306
identifier:table	Name of the table containing users

Warning

Table 11.2. Basic smb.conf options for MySQL passdb backend

Field	Contents
identifier:mysql host	host name, defaults to 'localhost'
identifier:mysql password
identifier:mysql user	defaults to 'samba'
identifier:mysql database	defaults to 'samba'
identifier:mysql port	defaults to 3306
identifier:table	Name of the table containing users

Warning

Since the password for the MySQL user is stored in the smb.conf file, you should make the the smb.conf file readable only to the user that runs Samba This is considered a security bug and will be fixed soon. -

Names of the columns in this table (I've added column types those columns should have first):

Table 11.3. MySQL field names for MySQL passdb backend

Field	Type	Contents
identifier:logon time column	int(9)
identifier:logoff time column	int(9)
identifier:kickoff time column	int(9)
identifier:pass last set time column	int(9)
identifier:pass can change time column	int(9)
identifier:pass must change time column	int(9)
identifier:username column	varchar(255)	unix username
identifier:domain column	varchar(255)	NT domain user is part of
identifier:nt username column	varchar(255)	NT username
identifier:fullname column	varchar(255)	Full name of user
identifier:home dir column	varchar(255)	Unix homedir path
identifier:dir drive column	varchar(2)	Directory drive path (eg: 'H:')
identifier:logon script column	varchar(255)	Batch file to run on client side when logging on
identifier:profile path column	varchar(255)	Path of profile
identifier:acct desc column	varchar(255)	Some ASCII NT user data
identifier:workstations column	varchar(255)	Workstations user can logon to (or NULL for all)
identifier:unknown string column	varchar(255)	unknown string
identifier:munged dial column	varchar(255)	?
identifier:user sid column	varchar(255)	NT user SID
identifier:group sid column	varchar(255)	NT group ID
identifier:lanman pass column	varchar(255)	encrypted lanman password
identifier:nt pass column	varchar(255)	encrypted nt passwd
identifier:plain pass column	varchar(255)	plaintext password
identifier:acct control column	int(9)	nt user data
identifier:unknown 3 column	int(9)	unknown
identifier:logon divs column	int(9)	?
identifier:hours len column	int(9)	?
identifier:unknown 5 column	int(9)	unknown
identifier:unknown 6 column	int(9)	unknown

Names of the columns in this table (I've added column types those columns should have first):

Table 11.3. MySQL field names for MySQL passdb backend

Field	Type	Contents
identifier:logon time column	int(9)
identifier:logoff time column	int(9)
identifier:kickoff time column	int(9)
identifier:pass last set time column	int(9)
identifier:pass can change time column	int(9)
identifier:pass must change time column	int(9)
identifier:username column	varchar(255)	unix username
identifier:domain column	varchar(255)	NT domain user is part of
identifier:nt username column	varchar(255)	NT username
identifier:fullname column	varchar(255)	Full name of user
identifier:home dir column	varchar(255)	Unix homedir path
identifier:dir drive column	varchar(2)	Directory drive path (eg: 'H:')
identifier:logon script column	varchar(255)	Batch file to run on client side when logging on
identifier:profile path column	varchar(255)	Path of profile
identifier:acct desc column	varchar(255)	Some ASCII NT user data
identifier:workstations column	varchar(255)	Workstations user can logon to (or NULL for all)
identifier:unknown string column	varchar(255)	unknown string
identifier:munged dial column	varchar(255)	?
identifier:user sid column	varchar(255)	NT user SID
identifier:group sid column	varchar(255)	NT group ID
identifier:lanman pass column	varchar(255)	encrypted lanman password
identifier:nt pass column	varchar(255)	encrypted nt passwd
identifier:plain pass column	varchar(255)	plaintext password
identifier:acct control column	int(9)	nt user data
identifier:unknown 3 column	int(9)	unknown
identifier:logon divs column	int(9)	?
identifier:hours len column	int(9)	?
identifier:unknown 5 column	int(9)	unknown
identifier:unknown 6 column	int(9)	unknown

Eventually, you can put a colon (:) after the name of each column, which should specify the column to update when updating the table. You can also specify nothing behind the colon - then the data from the field will not be updated. -

Using plaintext passwords or encrypted password

I strongly discourage the use of plaintext passwords, however, you can use them:

If you would like to use plaintext passwords, set @@ -765,7 +766,7 @@ access to attrs=lmPassword,ntPassword

If you use encrypted passwords, set the 'identifier:plain pass column' to 'NULL' (without the quotes). This is the default. -

Getting non-column data from the table

It is possible to have not all data in the database and making some 'constant'.

For example, you can set 'identifier:fullname column' to : @@ -780,30 +781,30 @@ access to attrs=lmPassword,ntPassword

To import data, use: $ pdbedit -i xml:filename -

Common Errors

Users can not logon - Users not in Samba SAM

Common Errors

Users can not logon - Users not in Samba SAM

People forget to put their users in their backend and then complain Samba won't authorize them. -

Users are being added to the wrong backend database

A few complaints have been received from users that just moved to Samba-3. The following smb.conf file entries were causing problems, new accounts were being added to the old smbpasswd file, not to the tdbsam passdb.tdb file: -

+	

+	 	[globals]
 		...
 		passdb backend = smbpasswd, tdbsam, guest
 		...
-	

-	

+

Samba will add new accounts to the first entry in the passdb backend parameter entry. If you want to update to the tdbsam, then change the entry to: -

+	

+	 	[globals]
 		...
 		passdb backend = tdbsam, smbpasswd, guest
 		...
-	

-

auth methods does not work

+ +

auth methods does not work

If you explicitly set an 'auth methods' parameter, guest must be specified as the first entry on the line. Eg: auth methods = guest sam.

-- cgit