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diff --git a/docs/docbook/projdoc/Samba-LDAP-HOWTO.sgml b/docs/docbook/projdoc/Samba-LDAP-HOWTO.sgml index e69de29bb2..a3aed0a617 100644 --- a/docs/docbook/projdoc/Samba-LDAP-HOWTO.sgml +++ b/docs/docbook/projdoc/Samba-LDAP-HOWTO.sgml @@ -0,0 +1,463 @@ +<chapter id="samba-ldap-howto"> + + +<chapterinfo> + <author> + <firstname>Gerald (Jerry)></firstname><surname>Carter></surname> + <affiliation> + <orgname>Samba Team</orgname> + <address><email>jerry@samba.org</email></address> + </affiliation> + </author> + + + <pubdate> (29 Dec 2001) </pubdate> +</chapterinfo> + +<title>Storing Samba's User/Machine Account information in an LDAP Directory</title> + +<sect1> +<title>Purpose</title> + +<para> +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. +</para> + +<itemizedlist> + <listitem><para>OpenLDAP - <ulink url="http://www.openldap.org/">http://www.openldap.org/</ulink></para></listitem> + <listitem><para>iPlanet Directory Server - <ulink url="http://iplanet.netscape.com/directory">http://iplanet.netscape.com/directory</ulink></para></listitem> +</itemizedlist> + +<para> +Note that <ulink url="http://www.ora.com/">O'Reilly Publishing</ulink> is working on +a guide to LDAP for System Administrators which has a planned release date of +early summer, 2002. +</para> + +<para>It may also be helpful to suppplement the reading of the HOWTO with +the <ulink url="http://www.unav.es/cti/ldap-smb/ldap-smb-2_2-howto.html">Samba-PDC-LDAP-HOWTO</ulink> +maintained by Ignacio Coupeau. +</para> + +</sect1> + + +<sect1> +<title>Introduction</title> + +<para> +Traditionally, when configuring <ulink url="smb.conf.5.html#ENCRYPTPASSWORDS">"encrypt +passwords = yes"</ulink> in Samba's <filename>smb.conf</filename> file, user account +information such as username, LM/NT password hashes, password change times, and account +flags have been stored in the <filename>smbpasswd(5)</filename> file. There are several +disadvantages to this approach for sites with very large numbers of users (counted +in the thousands). +</para> + +<para> +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. +</para> + +<para> +The second problem is that administrators which desired to replicate an +smbpasswd file to more than one Samba server were left to use external +tools such as <command>rsync(1)</command> and <command>ssh(1)</command> +and write custom, in-house scripts. +</para> + +<para> +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). +</para> + +<para> +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. <parameter>--with-ldapsam</parameter> or +<parameter>--with-tdbsam</parameter>) requires compile time support. +</para> + +<para> +When compiling Samba to include the <parameter>--with-ldapsam</parameter> 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. +</para> + +<para> +There are a few points to stress about what the <parameter>--with-ldapsam</parameter> +does not provide. The LDAP support referred to in the this documentat does not +include: +</para> + +<itemizedlist> + <listitem><para>A means of retrieving user account information from + an Windows 2000 Active Directory server.</para></listitem> + <listitem><para>A means of replacing /etc/passwd.</para></listitem> +</itemizedlist> + +<para> +The second item can be accomplished by using LDAP NSS and PAM modules. LGPL +versions of these libraries can be obtained from PADL Software +(<ulink url="http://www.padl.com/">http://www.padl.com/</ulink>). However, +the details of configuring these packages i beyond the scope of this document. +</para> + +</sect1> + +<sect1> +<title>Supported LDAP Servers</title> + +<para> +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 bounds to be compile errors and bugs. These should not be +hard to fix. If you are so inclined, please be sure to forward all pacthes to +<ulink url="samba-patches@samba.org">samba-patches@samba.org</ulink> and +<ulink url="jerry@samba.org">jerry@samba.org</ulink>. +</para> + +</sect1> + + + + +<sect1> +<title>Schema and Relationship to the RFC 2307 posixAccount</title> + + +<para> +Samba 2.2.3 includes the necessary schema file for OpenLDAP 2.0 in +<filename>examples/LDAP/samba.schema</filename>. (Note that this schema +file has been modified since the experimental support initially included +in 2.2.2). The sambaAccount objectclass is given here: +</para> + +<para><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 )) +</programlisting></para> + +<para> +The samba.schema file has been formatted for OpenLDAP 2.0. The OID's are +owned by the Samba Team and as such as 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 <ulink +url="jerry@samba.org">jerry@samba.org</ulink> +</para> + +<para> +Just as the smbpasswd file is mean to store information which supplements a +user's <filename>/etc/passwd</filename> entry, so is the sambaAccount object +meant to supplement the UNIX user account information. A sambaAccount is a +<constant>STRUCTURAL</constant> 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. +</para> + +<para> +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 mkes it posible 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 infratrsucture. +</para> + +<para> +To include support for the sambaAccount object in an OpenLDAP directory +server, first copy the samba.schema file to slapd's configuration directory. +</para> + +<para> +<prompt>root# </prompt><command>cp samba.schema /etc/openldap/schema/</command> +</para> + +<para> +Next, include the <filename>samba.schema</filename> file in <filename>slapd.conf</filename>. +The sambaAccount object contains two attributes which depend upon other schema +files. The 'uid' attribute is defined in <filename>cosine.schema</filename> and +the 'displayName' attribute is defined in the <filename>inetorgperson.schema</filename> +file. Bother of these must be included before the <filename>samba.schema</filename> file. +</para> + +<para><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 + +.... +</programlisting></para> + + +</sect1> + + + +<sect1> +<title>smb.conf LDAP parameters</title> + + +<para> +The following parameters are available in smb.conf only with <parameter>--with-ldapsam</parameter> +was included with compiling Samba. +</para> + +<itemizedlist> + <listitem><para><ulink url="smb.conf.5.html#LDAPSSL">ldap ssl</ulink></para></listitem> + <listitem><para><ulink url="smb.conf.5.html#LDAPSERVER">ldap server</ulink></para></listitem> + <listitem><para><ulink url="smb.conf.5.html#LDAPADMINDN">ldap admin dn</ulink></para></listitem> + <listitem><para><ulink url="smb.conf.5.html#LDAPSUFFIX">ldap suffix</ulink></para></listitem> + <listitem><para><ulink url="smb.conf.5.html#LDAPFILTER">ldap filter</ulink></para></listitem> + <listitem><para><ulink url="smb.conf.5.html#LDAPPORT">ldap port</ulink></para></listitem> +</itemizedlist> + +<para> +These are described in the <ulink url="smb.conf.5.html">smb.conf(5)</ulink> man +page and so will not be repeated here. However, a sample smb.conf file for +use with an LDAP directory could appear as +</para> + +<para><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 <replaceable>secretpw</replaceable>' 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 = "(&(uid=%u)(objectclass=sambaAccount))" +</programlisting></para> + + + +</sect1> + + + + +<sect1> +<title>Security and sambaAccount</title> + + +<para> +There are two important points to remember when discussing the security +of sambaAccount entries in the directory. +</para> + +<itemizedlist> + <listitem><para><emphasis>Never</emphasis> retrieve the lmPassword or + ntPassword attribute values over and unencrypted LDAP session.</para></listitem> + <listitem><para><emphasis>Never</emphasis> allow non-admin users to + view the lmPassword or ntPassword attribute values.</para></listitem> +</itemizedlist> + +<para> +These password hashes are clear text equivalents and can be used to impersonate +the user without deriving the original clear text strings. +</para> + +<para> +To remedy the first security issue, the "ldap ssl" smb.conf parameter defaults +to require an encrypted session (<command>ldap ssl = on</command>) 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 +(<command>ldap ssl = off</command>). +</para> + +<para> +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 <filename>slapd.conf</filename>: +</para> + +<para><programlisting> +## allow users to update their own password, but not to browse others +access to attrs=userPassword,lmPassword,ntPassword + by self write + by * auth +</programlisting></para> + +<para> +You may of course, add in write access to administrative DN's as necessary. +</para> + +</sect1> + + + +<sect1> +<title></title> + + +<para> +There are currently four sambaAccount attributes which map directly onto +<filename>smb.conf</filename> parameters. +</para> + +<itemizedlist> + <listitem><para>smbHome -> "logon home"</para></listitem> + <listitem><para>profilePath -> "logon path"</para></listitem> + <listitem><para>homeDrive -> "logon drive"</para></listitem> + <listitem><para>scriptPath -> "logon script"</para></listitem> +</itemizedlist> + +<para> +First of all, these parameters are only used when Samba is acting as a +PDC or a domain (refer to the <ulink url="Samba-PDC-HOWTO.html">Samba-PDC-HOWTO</ulink> +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 <command>logon home = \\%L\%u</command> was defined in +its <filename>smb.conf</filename> file. Assuming <filename>smb.conf</filename> +also contains , when a user named "becky" logons to the domain, the <parameter>logon +home</parameter> string is expanded to \\TASHTEGO\becky. +</para> + +<para> +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 <parameter>logon home</parameter> 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). +</para> + + +</sect1> + + + + +<sect1> +<title>Example LDIF Entries for a sambaAccount</title> + + +<para> +The following is a working LDIF with the inclusion of the posixAccount objectclass: +</para> + +<para><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 +</programlisting></para> + +<para> +The following is an LDIF entry for using both the sambaAccount and +posixAccount objectclasses: +</para> + +<para><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 +</programlisting></para> + + +</sect1> + + + +<sect1> +<title>Comments</title> + + +<para> +Please mail all comments regarding this HOWTO to <ulink +url="mailto:jerry@samba.org">jerry@samba.org</ulink>. This documents was +last updated to reflect the Samba 2.2.3 release. + +</para> + + +</sect1> + + +</chapter> |