Samba-LDAP-HOWTO.html [plain text]
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>Storing Samba's User/Machine Account information in an LDAP Directory</TITLE
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><DIV
CLASS="ARTICLE"
><DIV
CLASS="TITLEPAGE"
><H1
CLASS="TITLE"
><A
NAME="SAMBA-LDAP-HOWTO"
>Storing Samba's User/Machine Account information in an LDAP Directory</A
></H1
><HR></DIV
><DIV
CLASS="SECT1"
><H1
CLASS="SECT1"
><A
NAME="AEN3"
>Purpose</A
></H1
><P
>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.</P
><P
></P
><UL
><LI
><P
>OpenLDAP - <A
HREF="http://www.openldap.org/"
TARGET="_top"
>http://www.openldap.org/</A
></P
></LI
><LI
><P
>iPlanet Directory Server - <A
HREF="http://iplanet.netscape.com/directory"
TARGET="_top"
>http://iplanet.netscape.com/directory</A
></P
></LI
></UL
><P
>Note that <A
HREF="http://www.ora.com/"
TARGET="_top"
>O'Reilly Publishing</A
> is working on
a guide to LDAP for System Administrators which has a planned release date of
early summer, 2002.</P
><P
>Two additional Samba resources which may prove to be helpful are</P
><P
></P
><UL
><LI
><P
>The <A
HREF="http://www.unav.es/cti/ldap-smb/ldap-smb-2_2-howto.html"
TARGET="_top"
>Samba-PDC-LDAP-HOWTO</A
>
maintained by Ignacio Coupeau.</P
></LI
><LI
><P
>The NT migration scripts from <A
HREF="http://samba.idealx.org/"
TARGET="_top"
>IDEALX</A
> that are
geared to manage users and group in such a Samba-LDAP Domain Controller configuration.
</P
></LI
></UL
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN23"
>Introduction</A
></H1
><P
>Traditionally, when configuring <A
HREF="smb.conf.5.html#ENCRYPTPASSWORDS"
TARGET="_top"
>"encrypt
passwords = yes"</A
> in Samba's <TT
CLASS="FILENAME"
>smb.conf</TT
> file, user account
information such as username, LM/NT password hashes, password change times, and account
flags have been stored in the <TT
CLASS="FILENAME"
>smbpasswd(5)</TT
> file. There are several
disadvantages to this approach for sites with very large numbers of users (counted
in the thousands).</P
><P
></P
><UL
><LI
><P
>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 lareg sites. What is needed is an indexed approach
such as is used in databases.</P
></LI
><LI
><P
>The second problem is that administrators who desired to replicate a
smbpasswd file to more than one Samba server were left to use external
tools such as <B
CLASS="COMMAND"
>rsync(1)</B
> and <B
CLASS="COMMAND"
>ssh(1)</B
>
and wrote custom, in-house scripts.</P
></LI
><LI
><P
>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
Identified (RID).</P
></LI
></UL
><P
>As a result of these defeciencies, 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 CVS trees). In Samba 2.2.3, enabling support
for a samdb backend (e.g. <TT
CLASS="PARAMETER"
><I
>--with-ldapsam</I
></TT
> or
<TT
CLASS="PARAMETER"
><I
>--with-tdbsam</I
></TT
>) requires compile time support.</P
><P
>When compiling Samba to include the <TT
CLASS="PARAMETER"
><I
>--with-ldapsam</I
></TT
> autoconf
option, smbd (and associated tools) will store and lookup user accounts in
an LDAP directory. In reality, this is very easy to understand. If you are
comfortable with using an smbpasswd file, simply replace "smbpasswd" with
"LDAP directory" in all the documentation.</P
><P
>There are a few points to stress about what the <TT
CLASS="PARAMETER"
><I
>--with-ldapsam</I
></TT
>
does not provide. The LDAP support referred to in the this documentation does not
include:</P
><P
></P
><UL
><LI
><P
>A means of retrieving user account information from
an Windows 2000 Active Directory server.</P
></LI
><LI
><P
>A means of replacing /etc/passwd.</P
></LI
></UL
><P
>The second item can be accomplished by using LDAP NSS and PAM modules. LGPL
versions of these libraries can be obtained from PADL Software
(<A
HREF="http://www.padl.com/"
TARGET="_top"
>http://www.padl.com/</A
>). However,
the details of configuring these packages are beyond the scope of this document.</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN52"
>Supported LDAP Servers</A
></H1
><P
>The LDAP samdb code in 2.2.3 has been developed and tested using the OpenLDAP
2.0 server and client libraries. The same code should be able to work with
Netscape's Directory Server and client SDK. However, due to lack of testing
so far, there are bound to be compile errors and bugs. These should not be
hard to fix. If you are so inclined, please be sure to forward all patches to
<A
HREF="samba-patches@samba.org"
TARGET="_top"
>samba-patches@samba.org</A
> and
<A
HREF="jerry@samba.org"
TARGET="_top"
>jerry@samba.org</A
>.</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN57"
>Schema and Relationship to the RFC 2307 posixAccount</A
></H1
><P
>Samba 2.2.3 includes the necessary schema file for OpenLDAP 2.0 in
<TT
CLASS="FILENAME"
>examples/LDAP/samba.schema</TT
>. (Note that this schema
file has been modified since the experimental support initially included
in 2.2.2). The sambaAccount objectclass is given here:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>objectclass ( 1.3.1.5.1.4.1.7165.2.2.2 NAME 'sambaAccount' SUP top STRUCTURAL
DESC 'Samba Account'
MUST ( uid $ rid )
MAY ( cn $ lmPassword $ ntPassword $ pwdLastSet $ logonTime $
logoffTime $ kickoffTime $ pwdCanChange $ pwdMustChange $ acctFlags $
displayName $ smbHome $ homeDrive $ scriptPath $ profilePath $
description $ userWorkstations $ primaryGroupID $ domain ))</PRE
></P
><P
>The samba.schema file has been formatted for OpenLDAP 2.0. 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 <A
HREF="jerry@samba.org"
TARGET="_top"
>jerry@samba.org</A
></P
><P
>Just as the smbpasswd file is mean to store information which supplements a
user's <TT
CLASS="FILENAME"
>/etc/passwd</TT
> entry, so is the sambaAccount object
meant to supplement the UNIX user account information. A sambaAccount is a
<TT
CLASS="CONSTANT"
>STRUCTURAL</TT
> 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.</P
><P
>In order to store all user account information (UNIX and Samba) in the directory,
it is necessary to use the sambaAccount 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.</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN69"
>Configuring Samba with LDAP</A
></H1
><DIV
CLASS="SECT2"
><H2
CLASS="SECT2"
><A
NAME="AEN71"
>OpenLDAP configuration</A
></H2
><P
>To include support for the sambaAccount object in an OpenLDAP directory
server, first copy the samba.schema file to slapd's configuration directory.</P
><P
><TT
CLASS="PROMPT"
>root# </TT
><B
CLASS="COMMAND"
>cp samba.schema /etc/openldap/schema/</B
></P
><P
>Next, include the <TT
CLASS="FILENAME"
>samba.schema</TT
> file in <TT
CLASS="FILENAME"
>slapd.conf</TT
>.
The sambaAccount object contains two attributes which depend upon other schema
files. The 'uid' attribute is defined in <TT
CLASS="FILENAME"
>cosine.schema</TT
> and
the 'displayName' attribute is defined in the <TT
CLASS="FILENAME"
>inetorgperson.schema</TT
>
file. Bother of these must be included before the <TT
CLASS="FILENAME"
>samba.schema</TT
> file.</P
><P
><PRE
CLASS="PROGRAMLISTING"
>## /etc/openldap/slapd.conf
## schema files (core.schema is required by default)
include /etc/openldap/schema/core.schema
## needed for sambaAccount
include /etc/openldap/schema/cosine.schema
include /etc/openldap/schema/inetorgperson.schema
include /etc/openldap/schema/samba.schema
## uncomment this line if you want to support the RFC2307 (NIS) schema
## include /etc/openldap/schema/nis.schema
....</PRE
></P
><P
>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 sambaAccount objectclasses
(and possibly posixAccount and posixGroup as well).</P
><P
><PRE
CLASS="PROGRAMLISTING"
># Indices to maintain
## required by OpenLDAP 2.0
index objectclass eq
## support pb_getsampwnam()
index uid pres,eq
## support pdb_getsambapwrid()
index rid eq
## uncomment these if you are storing posixAccount and
## posixGroup entries in the directory as well
##index uidNumber eq
##index gidNumber eq
##index cn eq
##index memberUid eq</PRE
></P
></DIV
><DIV
CLASS="SECT2"
><HR><H2
CLASS="SECT2"
><A
NAME="AEN88"
>Configuring Samba</A
></H2
><P
>The following parameters are available in smb.conf only with <TT
CLASS="PARAMETER"
><I
>--with-ldapsam</I
></TT
>
was included with compiling Samba.</P
><P
></P
><UL
><LI
><P
><A
HREF="smb.conf.5.html#LDAPSSL"
TARGET="_top"
>ldap ssl</A
></P
></LI
><LI
><P
><A
HREF="smb.conf.5.html#LDAPSERVER"
TARGET="_top"
>ldap server</A
></P
></LI
><LI
><P
><A
HREF="smb.conf.5.html#LDAPADMINDN"
TARGET="_top"
>ldap admin dn</A
></P
></LI
><LI
><P
><A
HREF="smb.conf.5.html#LDAPSUFFIX"
TARGET="_top"
>ldap suffix</A
></P
></LI
><LI
><P
><A
HREF="smb.conf.5.html#LDAPFILTER"
TARGET="_top"
>ldap filter</A
></P
></LI
><LI
><P
><A
HREF="smb.conf.5.html#LDAPPORT"
TARGET="_top"
>ldap port</A
></P
></LI
></UL
><P
>These are described in the <A
HREF="smb.conf.5.html"
TARGET="_top"
>smb.conf(5)</A
> man
page and so will not be repeated here. However, a sample smb.conf file for
use with an LDAP directory could appear as</P
><P
><PRE
CLASS="PROGRAMLISTING"
>## /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 <TT
CLASS="REPLACEABLE"
><I
>secretpw</I
></TT
>' to store the
# passphrase in the secrets.tdb file. If the "ldap admin dn" values
# changes, this password will need to be reset.
ldap admin dn = "cn=Samba Manager,ou=people,dc=samba,dc=org"
# specify the LDAP server's hostname (defaults to locahost)
ldap server = ahab.samba.org
# Define the SSL option when connecting to the directory
# ('off', 'start tls', or 'on' (default))
ldap ssl = start tls
# define the port to use in the LDAP session (defaults to 636 when
# "ldap ssl = on")
ldap port = 389
# 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=sambaAccount))"</PRE
></P
></DIV
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN116"
>Accounts and Groups management</A
></H1
><P
>As users accounts are managed thru the sambaAccount objectclass, you should
modify you existing administration tools to deal with sambaAccount attributes.</P
><P
>Machines accounts are managed with the sambaAccount objectclass, just
like users accounts. However, it's up to you to stored thoses accounts
in a different tree of you 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).</P
><P
>In Samba release 2.2.3, the group management system is based on posix
groups. This meand that Samba make usage of the posixGroup objectclass.
For now, there is no NT-like group system management (global and local
groups).</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN121"
>Security and sambaAccount</A
></H1
><P
>There are two important points to remember when discussing the security
of sambaAccount entries in the directory.</P
><P
></P
><UL
><LI
><P
><I
CLASS="EMPHASIS"
>Never</I
> retrieve the lmPassword or
ntPassword attribute values over an unencrypted LDAP session.</P
></LI
><LI
><P
><I
CLASS="EMPHASIS"
>Never</I
> allow non-admin users to
view the lmPassword or ntPassword attribute values.</P
></LI
></UL
><P
>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 <A
HREF="ENCRYPTION.html"
TARGET="_top"
>ENCRYPTION chapter</A
> of the Samba-HOWTO-Collection.</P
><P
>To remedy the first security issue, the "ldap ssl" smb.conf parameter defaults
to require an encrypted session (<B
CLASS="COMMAND"
>ldap ssl = on</B
>) using
the default port of 636
when contacting the directory server. When using an OpenLDAP 2.0 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
(<B
CLASS="COMMAND"
>ldap ssl = off</B
>).</P
><P
>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.</P
><P
>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 <TT
CLASS="FILENAME"
>slapd.conf</TT
>:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>## 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</PRE
></P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN141"
>LDAP specials attributes for sambaAccounts</A
></H1
><P
>The sambaAccount objectclass is composed of the following attributes:</P
><P
></P
><UL
><LI
><P
><TT
CLASS="CONSTANT"
>lmPassword</TT
>: the LANMAN password 16-byte hash stored as a character
representation of a hexidecimal string.</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>ntPassword</TT
>: the NT password hash 16-byte stored as a character
representation of a hexidecimal string.</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>pwdLastSet</TT
>: The integer time in seconds since 1970 when the
<TT
CLASS="CONSTANT"
>lmPassword</TT
> and <TT
CLASS="CONSTANT"
>ntPassword</TT
> attributes were last set.
</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>acctFlags</TT
>: string of 11 characters surrounded by square brackets []
representing account flags such as U (user), W(workstation), X(no password expiration), and
D(disabled).</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>logonTime</TT
>: Integer value currently unused</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>logoffTime</TT
>: Integer value currently unused</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>kickoffTime</TT
>: Integer value currently unused</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>pwdCanChange</TT
>: Integer value currently unused</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>pwdMustChange</TT
>: Integer value currently unused</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>homeDrive</TT
>: specifies 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.</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>scriptPath</TT
>: The 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.</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>profilePath</TT
>: specifies 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.</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>smbHome</TT
>: The 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(5) man page for more information.
</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>userWorkstation</TT
>: character string value currently unused.
</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>rid</TT
>: the integer representation of the user's relative identifier
(RID).</P
></LI
><LI
><P
><TT
CLASS="CONSTANT"
>primaryGroupID</TT
>: the relative identifier (RID) of the primary group
of the user.</P
></LI
></UL
><P
>The majority of these parameters are only used when Samba is acting as a PDC of
a domain (refer to the <A
HREF="Samba-PDC-HOWTO.html"
TARGET="_top"
>Samba-PDC-HOWTO</A
> for details on
how to configure Samba as a Primary Domain Controller). The following four attributes
are only stored with the sambaAccount entry if the values are non-default values:</P
><P
></P
><UL
><LI
><P
>smbHome</P
></LI
><LI
><P
>scriptPath</P
></LI
><LI
><P
>logonPath</P
></LI
><LI
><P
>homeDrive</P
></LI
></UL
><P
>These attributes are only stored with the sambaAccount entry if
the values are non-default values. For example, assume TASHTEGO has now been
configured as a PDC and that <B
CLASS="COMMAND"
>logon home = \\%L\%u</B
> was defined in
its <TT
CLASS="FILENAME"
>smb.conf</TT
> file. When a user named "becky" logons to the domain,
the <TT
CLASS="PARAMETER"
><I
>logon home</I
></TT
> 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 <TT
CLASS="PARAMETER"
><I
>logon home</I
></TT
> parameter is used in its place. Samba
will only write the attribute value to the directory entry is the value is
something other than the default (e.g. \\MOBY\becky).</P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN211"
>Example LDIF Entries for a sambaAccount</A
></H1
><P
>The following is a working LDIF with the inclusion of the posixAccount objectclass:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>dn: uid=guest2, ou=people,dc=plainjoe,dc=org
ntPassword: 878D8014606CDA29677A44EFA1353FC7
pwdMustChange: 2147483647
primaryGroupID: 1201
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
pwdLastSet: 1010179124
logonTime: 0
objectClass: sambaAccount
uid: guest2
kickoffTime: 2147483647
acctFlags: [UX ]
logoffTime: 2147483647
rid: 19006
pwdCanChange: 0</PRE
></P
><P
>The following is an LDIF entry for using both the sambaAccount and
posixAccount objectclasses:</P
><P
><PRE
CLASS="PROGRAMLISTING"
>dn: uid=gcarter, ou=people,dc=plainjoe,dc=org
logonTime: 0
displayName: Gerald Carter
lmPassword: 552902031BEDE9EFAAD3B435B51404EE
primaryGroupID: 1201
objectClass: posixAccount
objectClass: sambaAccount
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</PRE
></P
></DIV
><DIV
CLASS="SECT1"
><HR><H1
CLASS="SECT1"
><A
NAME="AEN219"
>Comments</A
></H1
><P
>Please mail all comments regarding this HOWTO to <A
HREF="mailto:jerry@samba.org"
TARGET="_top"
>jerry@samba.org</A
>. This documents was
last updated to reflect the Samba 2.2.3 release. </P
></DIV
></DIV
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