&author.jelmer;
&author.jerry;
&author.jeremy;
&author.jht;
Olivier (lem)LemaireIDEALXolem@IDEALX.orgMay 24, 2003Account Information Databases
Samba-3 implements a new capability to work concurrently with mulitple 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.
This chapter describes the new functionality and how to get the most out of it.
In the course of development of Samba-3 a number of requests were received to provide the
ability to migrate MS Windows NT4 SAM accounts to Samba-3 without the need to provide
matching Unix/Linux accounts. We called this the Non Unix Accounts (NUA)
capability. The intent was that an administrator could decide to use the tdbsam
backend and by simply specifying "passdb backend = tdbsam_nua, guest"
this would allow Samba-3 to implement a solution that did not use Unix accounts per se. Late
in the development cycle the team doing this work hit upon some obstacles that prevents this
solution from being used. Given the delays with Samba-3 release a decision was made to NOT
deliver this functionality until a better method of recognising NT Group SIDs from NT User
SIDs could be found. This feature may thus return during the life cycle for the Samba-3 series.
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 BackendsPlain Text:
This option uses nothing but the Unix/Linux /etc/passwd
style back end. On systems that have PAM (Pluggable Authentication Modules)
support all PAM modules are supported. The behaviour is just as it was with
Samba-2.2.x, and the protocol limitations imposed by MS Windows clients
apply likewise.
smbpasswd:
This option allows continues use of the smbpasswd
file that maintains a plain ASCII (text) layout that includes the MS Windows
LanMan and NT encrypted passwords as well as a field that stores some
account information. This form of password backend does NOT store any of
the MS Windows NT/200x SAM (Security Account Manager) information needed to
provide the extended controls that are needed for more comprehensive
interoperation with MS Windows NT4 / 200x servers.
This backend should be used only for backwards compatibility with older
versions of Samba. It may be deprecated in future releases.
ldapsam_compat (Samba-2.2 LDAP Compatibilty):
There is a password backend option that allows continued operation with
a existing OpenLDAP backend that uses the Samba-2.2.x LDAP schema extension.
This option is provided primarily as a migration tool, although there is
no reason to force migration at this time. Note that this tool will eventually
be deprecated.
Samba-3 introduces the following new password backend capabilities:
New Backendsguest:
This is always required as the last backend specified.
It provides the ability to handle guest account requirements for access to
resources like IPC$ which is used for browsing.
tdbsam:
This backend provides a rich database backend for local servers. This
backend is NOT suitable for multiple domain controller (ie: PDC + one
or more BDC) installations.
The tdbsam password backend stores the old
smbpasswd information PLUS the extended MS Windows NT / 200x
SAM information into a binary format TDB (trivial database) file.
The inclusion of the extended information makes it possible for Samba-3
to implement the same account and system access controls that are possible
with MS Windows NT4 and MS Windows 200x based systems.
The inclusion of the tdbsam capability is a direct
response to user requests to allow simple site operation without the overhead
of the complexities of running OpenLDAP. It is recommended to use this only
for sites that have fewer than 250 users. For larger sites or implementations
the use of OpenLDAP or of Active Directory integration is strongly recommended.
ldapsam:
This provides a rich directory backend for distributed account installation
Samba-3 has a new and extended LDAP implementation that requires configuration
of OpenLDAP with a new format samba schema. The new format schema file is
included in the ~samba/examples/LDAP directory.
The new LDAP implementation significantly expands the control abilities that
were possible with prior versions of Samba. It is now possible to specify
"per user" profile settings, home directories, account access controls, and
much more. Corporate sites will see that the Samba-Team has listened to their
requests both for capability and to allow greater scalability.
mysqlsam (MySQL based backend):
It is expected that the MySQL based SAM will be very popular in some corners.
This database backend will be on considerable interest to sites that want to
leverage existing MySQL technology.
xmlsam (XML based datafile):
Allows the account and password data to be stored in an XML format
data file. This backend can not be used for normal operation, it can only
be used in conjunction with pdbedit's pdb2pdb
functionality. The DTD that is used might be subject to changes in the future.
The xmlsam option can be useful for account migration between database
backends or backups. Use of this tool will allow the data to be edited before migration
into another backend format.
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.
Newer windows clients send encrypted passwords (so-called Lanman and NT hashes) over
the wire, instead of plain text passwords. The newest clients will send only encrypted
passwords and refuse to send plain text passwords, unless their registry is tweaked.
These passwords can't be converted to unix style encrypted passwords. Because of that
you can't use the standard unix user database, and you have to store the Lanman and NT
hashes somewhere else.
In addition to differently encrypted passwords, windows also stores certain data for each
user that is not stored in a unix user database. e.g: workstations the user may logon from,
the location where the users' profile is stored, and so on. Samba retrieves and stores this
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
never sends the cleartext password over the network but it does store the 16 byte
hashed values on disk. This is also bad. Why? Because the 16 byte hashed values
are a "password equivalent". You cannot derive the user's password from them, but
they could potentially be used in a modified client to gain access to a server.
This would require considerable technical knowledge on behalf of the attacker but
is perfectly possible. You should thus treat the data stored in whatever passdb
backend you use (smbpasswd file, ldap, mysql) as though it contained the cleartext
passwords of all your users. Its contents must be kept secret, and the file should
be protected accordingly.
Ideally we would like a password scheme that involves neither plain text passwords
on the net nor on disk. Unfortunately this is not available as Samba is stuck with
having to be compatible with other SMB systems (WinNT, WfWg, Win95 etc).
Windows NT 4.0 Service pack 3 changed the default setting so that plaintext passwords
are disabled from being sent over the wire. This mandates either the use of encrypted
password support or edit the Windows NT registry to re-enable plaintext passwords.
The following versions of MS Windows do not support full domain security protocols,
although they may log onto a domain environment:
MS DOS Network client 3.0 with the basic network redirector installedWindows 95 with the network redirector update installedWindows 98 [se]Windows Me
MS Windows XP Home does not have facilities to become a domain member and it can
not participate in domain logons.
The following versions of MS Windows fully support domain security protocols.
Windows NT 3.5xWindows NT 4.0Windows 2000 ProfessionalWindows 200x Server/Advanced ServerWindows XP Professional
All current release of Microsoft SMB/CIFS clients support authentication via the
SMB Challenge/Response mechanism described here. Enabling clear text authentication
does not disable the ability of the client to participate in encrypted authentication.
Instead, it allows the client to negotiate either plain text _or_ encrypted password
handling.
MS Windows clients will cache the encrypted password alone. Where plain text passwords
are re-enabled, through the appropriate registry change, the plain text password is NEVER
cached. This means that in the event that a network connections should become disconnected
(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 PasswordsPlain 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
that does not support encrypted passwords. It will refuse
to browse the server if the server is also in user level
security mode. It will insist on prompting the user for the
password on each connection, which is very annoying. The
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 passwordsPlain 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 ftpUse 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
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.
Firstly, all Samba SAM (Security Account Management database) accounts require
a Unix/Linux UID that the account will map to. As users are added to the account
information database samba-3 will call the add user script
interface to add the account to the Samba host OS. In essence all accounts in
the local SAM require a local user account.
The second way to affect Windows SID to Unix UID mapping is via the
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 samba-3.0.1 release timing.
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.
smbpasswd works in a client-server mode where it contacts the
local smbd to change the user's password on its behalf.This has enormous benefits
as follows:
smbpasswd has the capability to change passwords on Windows NT
servers (this only works when the request is sent to the NT Primary Domain Controller
if changing an NT Domain user's password).
smbpasswd can be used to:
add user or machine accountsdelete user or machine accountsenable user or machine accountsdisable user or machine accountsset to NULL user passwordsmanage interdomain trust accounts
To run smbpasswd as a normal user just type:
$ smbpasswdOld SMB password: secret
For secret type old value here - or hit return if
there was no old password
New SMB Password: new secretRepeat 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.
When invoked by an ordinary user it will only allow change of their own
SMB password.
When run by root smbpasswd may take an optional argument, specifying
the user name whose SMB password you wish to change. When run as root, smbpasswd
does not prompt for or check the old password value, thus allowing root to set passwords
for users who have forgotten their passwords.
smbpasswd is designed to work in the way familiar to UNIX
users who use the passwd or yppasswd commands.
While designed for administrative use, this tool provides essential user level
password change capabilities.
For more details on using smbpasswd refer to the man page (the
definitive reference).
The pdbedit Commandpdbedit 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 accountslisting user accountsmigrate user accounts
The pdbedit tool is the only one that can manage the account
security and policy settings. It is capable of all operations that smbpasswd can
do as well as a super set of them.
One particularly important purpose of the pdbedit is to allow
the migration of account information from one passdb backend to another. See the
XML password backend section of this chapter.
The following is an example of the user account information that is stored in
a tdbsam password backend. This listing was produced by running:
$ pdbedit -Lv met
Unix username: met
NT username:
Account Flags: [UX ]
User SID: S-1-5-21-1449123459-1407424037-3116680435-2004
Primary Group SID: S-1-5-21-1449123459-1407424037-3116680435-1201
Full Name: Melissa E Terpstra
Home Directory: \\frodo\met\Win9Profile
HomeDir Drive: H:
Logon Script: scripts\logon.bat
Profile Path: \\frodo\Profiles\met
Domain: MIDEARTH
Account desc:
Workstations: melbelle
Munged dial:
Logon time: 0
Logoff time: Mon, 18 Jan 2038 20:14:07 GMT
Kickoff time: Mon, 18 Jan 2038 20:14:07 GMT
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 conduected via the way
that the samba host OS will access it's /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
flags have been stored in the smbpasswd(5) file. There are several
disadvantages to this approach for sites with very large numbers of users (counted
in the thousands).
The first is that all lookups must be performed sequentially. Given that
there are approximately two lookups per domain logon (one for a normal
session connection such as when mapping a network drive or printer), this
is a performance bottleneck for large sites. What is needed is an indexed approach
such as is used in databases.
The second problem is that administrators who desire to replicate a smbpasswd file
to more than one Samba server were left to use external tools such as
rsync(1) and ssh(1) and wrote custom,
in-house scripts.
And finally, the amount of information which is stored in an smbpasswd entry leaves
no room for additional attributes such as a home directory, password expiration time,
or even a Relative Identifier (RID).
As a result of these deficiencies, a more robust means of storing user attributes
used by smbd was developed. The API which defines access to user accounts
is commonly referred to as the samdb interface (previously this was called the passdb
API, and is still so named in the Samba CVS trees).
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.
tdbsamSamba 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.
As a general guide the Samba-Team do NOT recommend using the tdbsam backend for sites
that have 250 or more users. Additionally, tdbsam is not capable of scaling for use
in sites that require PDB/BDC implmentations 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
an Windows 200x Active Directory server.A means of replacing /etc/passwd.
The second item can be accomplished by using LDAP NSS and PAM modules. LGPL
versions of these libraries can be obtained from PADL Software
(http://www.padl.com/). More
information about the configuration of these packages may be found at "LDAP,
System Administration; Gerald Carter, O'Reilly; Chapter 6: Replacing NIS".
Refer to
http://safari.oreilly.com/?XmlId=1-56592-491-6 for those who might wish to know
more about configuration and administration of an OpenLDAP server.
This document describes how to use an LDAP directory for storing Samba user
account information traditionally stored in the smbpasswd(5) file. It is
assumed that the reader already has a basic understanding of LDAP concepts
and has a working directory server already installed. For more information
on LDAP architectures and Directories, please refer to the following sites.
OpenLDAP - http://www.openldap.org/iPlanet Directory Server -
http://iplanet.netscape.com/directory
Two additional Samba resources which may prove to be helpful are
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
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 Auxilary Account'
MUST ( uid $ rid )
MAY ( cn $ lmPassword $ ntPassword $ pwdLastSet $ logonTime $
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
submit the modified schema file as a patch to
jerry@samba.org.
Just as the smbpasswd file is meant to store information which supplements a
user's /etc/passwd entry, so is the sambaSamAccount object
meant to supplement the UNIX user account information. A sambaSamAccount is a
STRUCTURAL objectclass so it can be stored individually
in the directory. However, there are several fields (e.g. uid) which overlap
with the posixAccount objectclass outlined in RFC2307. This is by design.
In order to store all user account information (UNIX and Samba) in the directory,
it is necessary to use the sambaSamAccount and posixAccount objectclasses in
combination. However, smbd will still obtain the user's UNIX account
information via the standard C library calls (e.g. getpwnam(), et. al.).
This means that the Samba server must also have the LDAP NSS library installed
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.
&rootprompt;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)
include /etc/openldap/schema/core.schema
## needed for sambaSamAccount
include /etc/openldap/schema/cosine.schema
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 usefull 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
index cn pres,sub,eq
index sn pres,sub,eq
## required to support pdb_getsampwnam
index uid pres,sub,eq
## required to support pdb_getsambapwrid()
index displayName pres,sub,eq
## uncomment these if you are storing posixAccount and
## posixGroup entries in the directory as well
##index uidNumber eq
##index gidNumber eq
##index memberUid eq
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:
&rootprompt;/etc/init.d/slapd restartInitialise 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
objectclass: organization
dc: plainjoe
o: Terpstra Org Network
description: The Samba-3 Network LDAP Example
# Organizational Role for Directory Management
dn: cn=Manager,dc=plainjoe,dc=org
objectclass: organizationalRole
cn: Manager
description: Directory Manager
# Setting up container for users
dn: ou=People,dc=plainjoe,dc=org
objectclass: top
objectclass: organizationalUnit
ou: People
# Setting up admin handle for People OU
dn: cn=admin,ou=People,dc=plainjoe,dc=org
cn: admin
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.
Before Samba can access the LDAP server you need to stoe the LDAP admin password
into the Samba-3 secrets.tdb database by:
&rootprompt; smbpasswd -w secretConfiguring 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.
passdb backend = ldapsam:urlldap sslldap admin dnldap suffixldap filterldap machine suffixldap user suffixldap delete dnldap passwd syncldap trust ids
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
encrypt passwords = yes
netbios name = TASHTEGO
workgroup = NARNIA
# ldap related parameters
# define the DN to use when binding to the directory servers
# The password for this DN is not stored in smb.conf. Rather it
# must be set by using 'smbpasswd -w secretpw' to store the
# passphrase in the secrets.tdb file. If the "ldap admin dn" values
# change, this password will need to be reset.
ldap admin dn = "cn=Samba Manager,ou=people,dc=samba,dc=org"
# Define the SSL option when connecting to the directory
# ('off', 'start tls', or 'on' (default))
ldap ssl = start tls
# syntax: passdb backend = ldapsam:ldap://server-name[:port]
passdb backend = ldapsam:ldap://funball.samba.org, guest
# smbpasswd -x delete the entire dn-entry
ldap delete dn = no
# the machine and user suffix added to the base suffix
# wrote WITHOUT quotes. NULL siffixes by default
ldap user suffix = ou=People
ldap machine suffix = ou=Systems
# Trust unix account information in LDAP
# (see the smb.conf manpage for details)
ldap trust ids = Yes
# specify the base DN to use when searching the directory
ldap suffix = "ou=people,dc=samba,dc=org"
# generally the default ldap search filter is ok
# ldap filter = "(&(uid=%u)(objectclass=sambaSamAccount))"
Accounts and Groups management
As users accounts are managed thru the sambaSamAccount objectclass, you should
modify your existing administration tools to deal with sambaSamAccount attributes.
Machines accounts are managed with the sambaSamAccount objectclass, just
like users accounts. However, it's up to you to store thoses accounts
in a different tree of your LDAP namespace: you should use
"ou=Groups,dc=plainjoe,dc=org" to store groups and
"ou=People,dc=plainjoe,dc=org" to store users. Just configure your
NSS and PAM accordingly (usually, in the /etc/ldap.conf configuration
file).
In Samba release 3.0, the group management system is based on posix
groups. This means that Samba makes usage 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
ntPassword attribute values over an unencrypted LDAP session.Never allow non-admin users to
view the lmPassword or ntPassword attribute values.
These password hashes are clear text equivalents and can be used to impersonate
the user without deriving the original clear text strings. For more information
on the details of LM/NT password hashes, refer to the
Account Information Database section of this chapter.
To remedy the first security issue, the ldap ssl &smb.conf; parameter defaults
to require an encrypted session (ldap ssl = on) using
the default port of 636
when contacting the directory server. When using an OpenLDAP server, it
is possible to use the use the StartTLS LDAP extended operation in the place of
LDAPS. In either case, you are strongly discouraged to disable this security
(ldap ssl = off).
Note that the LDAPS protocol is deprecated in favor of the LDAPv3 StartTLS
extended operation. However, the OpenLDAP library still provides support for
the older method of securing communication between clients and servers.
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
The sambaSamAccount objectclass is composed of the following attributes:
Attributes in the sambaSamAccount objectclass (LDAP)lmPasswordthe LANMAN password 16-byte hash stored as a character
representation of a hexidecimal string.ntPasswordthe NT password hash 16-byte stored as a character
representation of a hexidecimal string.pwdLastSetThe integer time in seconds since 1970 when the
lmPassword and ntPassword attributes were last set.
acctFlagsstring of 11 characters surrounded by square brackets []
representing account flags such as U (user), W(workstation), X(no password expiration),
I(Domain trust account), H(Home dir required), S(Server trust account),
and D(disabled).logonTimeInteger value currently unusedlogoffTimeInteger value currently unusedkickoffTimeInteger value currently unusedpwdCanChangeInteger value currently unusedpwdMustChangeInteger value currently unusedhomeDrivespecifies the drive letter to which to map the
UNC path specified by homeDirectory. The drive letter must be specified in the form "X:"
where X is the letter of the drive to map. Refer to the "logon drive" parameter in the
smb.conf(5) man page for more information.scriptPathThe scriptPath property specifies the path of
the user's logon script, .CMD, .EXE, or .BAT file. The string can be null. The path
is relative to the netlogon share. Refer to the "logon script" parameter in the
smb.conf(5) man page for more information.profilePathspecifies a path to the user's profile.
This value can be a null string, a local absolute path, or a UNC path. Refer to the
"logon path" parameter in the smb.conf(5) man page for more information.smbHomeThe homeDirectory property specifies the path of
the home directory for the user. The string can be null. If homeDrive is set and specifies
a drive letter, homeDirectory should be a UNC path. The path must be a network
UNC path of the form \\server\share\directory. This value can be a null string.
Refer to the logon home parameter in the &smb.conf; man page for more information.
userWorkstationcharacter string value currently unused.
ridthe integer representation of the user's relative identifier
(RID).primaryGroupIDthe relative identifier (RID) of the primary group
of the user.domaindomain 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
are only stored with the sambaSamAccount entry if the values are non-default values:
smbHomescriptPathlogonPathhomeDrive
These attributes are only stored with the sambaSamAccount entry if
the values are non-default values. For example, assume TASHTEGO has now been
configured as a PDC and that logon home = \\%L\%u was defined in
its &smb.conf; file. When a user named "becky" logons to the domain,
the logon home string is expanded to \\TASHTEGO\becky.
If the smbHome attribute exists in the entry "uid=becky,ou=people,dc=samba,dc=org",
this value is used. However, if this attribute does not exist, then the value
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
primaryGroupID: 1201
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
pwdLastSet: 1010179124
logonTime: 0
objectClass: sambaSamAccount
uid: guest2
kickoffTime: 2147483647
acctFlags: [UX ]
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
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
primaryGroupID: 1201
objectClass: posixAccount
objectClass: sambaSamAccount
acctFlags: [UX ]
userPassword: {crypt}BpM2ej8Rkzogo
uid: gcarter
uidNumber: 9000
cn: Gerald Carter
loginShell: /bin/bash
logoffTime: 2147483647
gidNumber: 100
kickoffTime: 2147483647
pwdLastSet: 1010179230
rid: 19000
homeDirectory: /home/tashtego/gcarter
pwdCanChange: 0
pwdMustChange: 2147483647
ntPassword: 878D8014606CDA29677A44EFA1353FC7
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:yesWhen the user changes his password, update
ntPassword, lmPassword
and the password fields.noOnly update ntPassword and lmPassword.onlyOnly 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 -ppassworddatabasename > /path/to/samba/examples/pdb/mysql/mysql.dumpConfiguringThis 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 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 thru the &smb.conf; file in the [global] section.
Basic smb.conf options for MySQL passdb backendFieldContentsidentifier:mysql hosthost name, defaults to 'localhost'identifier:mysql passwordidentifier:mysql userdefaults to 'samba'identifier:mysql databasedefaults to 'samba'identifier:mysql portdefaults to 3306identifier:tableName of the table containing users
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):
MySQL field names for MySQL passdb backendFieldTypeContentsidentifier:logon time columnint(9)identifier:logoff time columnint(9)identifier:kickoff time columnint(9)identifier:pass last set time columnint(9)identifier:pass can change time columnint(9)identifier:pass must change time columnint(9)identifier:username columnvarchar(255)unix usernameidentifier:domain columnvarchar(255)NT domain user is part ofidentifier:nt username columnvarchar(255)NT usernameidentifier:fullname columnvarchar(255)Full name of useridentifier:home dir columnvarchar(255)Unix homedir pathidentifier:dir drive columnvarchar(2)Directory drive path (eg: 'H:')identifier:logon script columnvarchar(255)Batch file to run on client side when logging onidentifier:profile path columnvarchar(255)Path of profileidentifier:acct desc columnvarchar(255)Some ASCII NT user dataidentifier:workstations columnvarchar(255)Workstations user can logon to (or NULL for all)identifier:unknown string columnvarchar(255)unknown stringidentifier:munged dial columnvarchar(255)?identifier:user sid columnvarchar(255)NT user SIDidentifier:group sid columnvarchar(255)NT group IDidentifier:lanman pass columnvarchar(255)encrypted lanman passwordidentifier:nt pass columnvarchar(255)encrypted nt passwdidentifier:plain pass columnvarchar(255)plaintext passwordidentifier:acct control columnint(9)nt user dataidentifier:unknown 3 columnint(9)unknownidentifier:logon divs columnint(9)?identifier:hours len columnint(9)?identifier:unknown 5 columnint(9)unknownidentifier:unknown 6 columnint(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
'identifier:lanman pass column' and 'identifier:nt pass column' to
'NULL' (without the quotes) and 'identifier:plain pass column' to the
name of the column containing the plaintext passwords.
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 :
CONCAT(First_name,' ',Sur_name)
Or, set 'identifier:workstations column' to :
NULLSee the MySQL documentation for more language constructs.XMLThis module requires libxml2 to be installed.The usage of pdb_xml is pretty straightforward. To export data, use:
$ pdbedit -e xml:filename
(where filename is the name of the file to put the data in)
To import data, use:
$ pdbedit -i xml:filenameCommon ErrorsUsers 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 recieved 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
If you explicitly set an 'auth methods' parameter, guest must be specified as the first
entry on the line. Eg: auth methods = guest sam.
This is the exact opposite of the requirement for the passdb backed
option, where it must be the LAST parameter on the line.