samba-mirror/Samba-LDAP-HOWTO.html at b77eec91dc6b6df63dcff57fe465f0b4eb73d7a1

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Gerald Carter ca0ccee23f merge from 2.2

(This used to be commit 67c6a24344e31c417c8c6f5db27697e268524401)

2002-01-05 19:27:26 +00:00

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 <HTML
 ><HEAD
 ><TITLE
 >Storing Samba's User/Machine Account information in an LDAP Directory</TITLE
 ><META
 NAME="GENERATOR"
 CONTENT="Modular DocBook HTML Stylesheet Version 1.57"></HEAD
 ><BODY
 CLASS="ARTICLE"
 BGCOLOR="#FFFFFF"
 TEXT="#000000"
 LINK="#0000FF"
 VLINK="#840084"
 ALINK="#0000FF"
 ><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 normally 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
 >It may also be helpful to supplement the reading of the HOWTO with
 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
 ></DIV
 ><DIV
 CLASS="SECT1"
 ><HR><H1
 CLASS="SECT1"
 ><A
 NAME="AEN17"
 >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
 >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 non-optimal.  What is needed is an indexed approach such as is used in
 databases.</P
 ><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
 ><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
 ><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 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="AEN42"
 >Supported LDAP Servers</A
 ></H1
 ><P
 >The LDAP samdb code in 2.2.3 has been developed and tested using the OpenLDAP
 .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="AEN47"
 >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 ))</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
 ><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
 ></DIV
 ><DIV
 CLASS="SECT1"
 ><HR><H1
 CLASS="SECT1"
 ><A
 NAME="AEN71"
 >smb.conf LDAP parameters</A
 ></H1
 ><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=Manager,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 = "(&#38;(uid=%u)(objectclass=sambaAccount))"</PRE
 ></P
 ></DIV
 ><DIV
 CLASS="SECT1"
 ><HR><H1
 CLASS="SECT1"
 ><A
 NAME="AEN99"
 >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.</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
 >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 users to update their own password, but not to browse others
 access to attrs=userPassword,lmPassword,ntPassword
      by self write
      by * auth</PRE
 ></P
 ><P
 >You may of course, add in write access to administrative DN's as necessary.</P
 ></DIV
 ><DIV
 CLASS="SECT1"
 ><HR><H1
 CLASS="SECT1"
 ><A
 NAME="AEN118"
 ></A
 ></H1
 ><P
 >There are currently four sambaAccount attributes which map directly onto
 <TT
 CLASS="FILENAME"
 >smb.conf</TT
 > parameters.</P
 ><P
 ></P
 ><UL
 ><LI
 ><P
 >smbHome -&gt; "logon home"</P
 ></LI
 ><LI
 ><P
 >profilePath -&gt; "logon path"</P
 ></LI
 ><LI
 ><P
 >homeDrive -&gt; "logon drive"</P
 ></LI
 ><LI
 ><P
 >scriptPath -&gt; "logon script"</P
 ></LI
 ></UL
 ><P
 >First of all, these parameters are only used when Samba is acting as a
 PDC or 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).
 Furthermore, 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.</P
 ><P
 >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="AEN138"
 >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="AEN146"
 >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.&#13;</P
 ></DIV
 ></DIV
 ></BODY
 ></HTML
 >

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