2.0: Configuring LDAP

Replicated Failover Domain Controller and file server using LDAP


1.0. Configuring Samba

2.0. Configuring LDAP

3.0. Initialization LDAP Database

4.0. User Management

5.0. Heartbeat HA Configuration

6.0. DRBD

7.0. BIND DNS



2.0. Configuring LDAP

It is necessary to use LDAP as our backend to Samba which provides replication to the Backup Domain Controllers.

Please read the official OpenLDAP documentation for detailed explanations of the material covered here.

There are two methods for providing replication, the first and original design was using openldap’s “slurpd” to provide Master / Slave operation, the database is pushed to slaves which is defined in slapd.conf on the master LDAP server; here is an example of the original way defined in 2.2. slapd.conf Master slurpd.

replica     host=192.168.0.3:389
            suffix="dc=differentialdesign,dc=org"
            binddn="cn=syncuser,dc=differentialdesign,dc=org"
            bindmethod=simple credentials=SyncUser

To bind to the database the slave replicas will need to use “syncusers’s” password defined above as “credentials=SyncUser“. Initially you will need to manually populate the slave database as defined in section 3.4 Database Replication.

Openldap 2.2 Original Style Replication Configuration

Master

Slave(s)

A master LDAP database that pushes its database to the slaves providing a persistant connection.

The slave LDAP server requires no additional configuration, as long as it has correct ACL set in the database and slapd.conf.

The main restriction with using this original design is the ldap database needs to be restarted on both the master and the slave when adding additional replicas. It is also no longer under active development.


In version Openldap 2.3 delta-syncrepl was invented because the original syncrepl method used too much network bandwidth. Developers recommend you use the latest version of Openldap as version 2.2 was decommisioned over one year ago.

Openldap 2.2/2.3 syncrepl/delta-syncrepl LDAP Replication Configuration

Provider

Consumers(s)

The provider LDAP server does not need to be restarted when adding additional slave servers. Configurations will differ depending on your replication methods chosen for syncrepl/delta-syncrepl.

The consumer no longer needs to have its database manually added for initial population. It can request an update at a set interval, or provide a pesistant connection; for persistant connections delta-syncrepl is the recommended choice.

These modes of operation are known as syncrepl; which is included in the ldap daemon. This means we no longer need to run the additional slurpd daemon to replicate the database.

On the consumer syncrepl needs to know what mode to operate in: “refeshOnly” operation where the consumer requests an update from the provider at set time interval defined as “interval=00:00:10:00” which would pull the provider every 10 minutes. The more desirable way is to use “refrshAndPersist” which provides a persistant connection. Instead of using a time interval to poll the provider we have the parameter “retry="30 10 300 +" which means it will retry 10 times every 30 seconds, then every 300 seconds if connection is lost; “+” indicates indefinite number of retries.

If you are debugging LDAP and find this error in the logs:

Feb 8 00:55:24 node1 slapd2.3[6171]: <= bdb_equality_candidates: (sambaSIDList) index_param failed (18)

It can be ignored and means no harm, it is produced as a result of having the same entries in /etc/passwd or /etc/groups as your LDAP database and is considered normal operation.

2.1. Installing LDAP

This section is designed for configuring LDAP and our overlays suited for delta-syncrepl replication.

We will compile LDAP from source so we can use the lastest version of Openldap.

People often run into problems installing ldap; however if you read the documentation and understand what you are doing things can be quite painless.

It is a good idea to understand modules and their file locations so you can properly setup your slapd.conf.

When compiling from source remove any other previous versions to aviod complications.

Get the lastest version of Openldap here http://www.openldap.org/software/download/


I deffinetly recommend compiling from source, however you can obtain Openldap2.3 RPM packages here for RHE4, CentOS, all versions of Fedora.

For x86 : http://anorien.warwick.ac.uk/mirrors/buchan/rhel4/openldap/

For x86-64: http://anorien.warwick.ac.uk/mirrors/buchan/rhel4-x86_64/openldap/


Step1.

Extract the contents of the file in a suitable location; I put it in /programs/openldap/release.

[root@node1 release]# tar zxvf openldap-2.3.33.tgz

Step2.

Change to the openldap directory.

[root@node1 release]# cd openldap-2.3.33

Step3.

This will take some time; when it has completed it will ask us to run "make depend"

[root@node1 openldap-2.3.33]# ./configure --prefix=/usr/local --enable-slapd --enable-syslog --with-cyrus-sasl=yes --enable-dynamic --enable-rewrite --disable-ipv6 --disable-shell --disable-sql --with-threads --enable-modules --enable-backends=mod --enable-overlays=mod --with-tls --enable-wrapper

If you run into any dependency problems here, you will need to resolve the issue before continueing.

configure: error: could not locate libtool ltdl.h

You may need to recompile libtools as below.

[root@node1 openldap-2.3.33]# /usr/share/libtool/libltdl
[root@node1 libltdl]# ./configure
[root@node1 libltdl]# make
[root@node1 libltdl]# make install


Step4.

Please run "make depend" to build dependencies

[root@node1 openldap-2.3.33]# make depend

Step5.

Now lets compile Openldap.

[root@node1 openldap-2.3.33]# make

Step6.

This step requires root privliges and will install Openldap onto our system.

[root@node1 openldap-2.3.33]# make install

Take particular note where the default installs to "/usr/local/etc/openldap/" this is where we configure the slapd.conf.

So we can provide certain features such as delta-syncrepl, accesslog, the BDB databases we need to configure the slapd.conf overlays to include the modules for the above features.

The module path is set to "/usr/local/libexec/openldap" this is where synprov, accesslog and back_bdb modules are located. There are also many more modulew available that you can load.

Step7.

Now we have compiled Openldap it is time to configure our slapd.conf on our primary node1; use this configuration file: slapd.conf Master delta-syncrepl Openldap2.3 slapd.conf

Step8.

Create the directories needed as specified in our delta-syncrepl slapd.conf. If you do not create these directories as specified in slapd.conf you will not be able to start ldap, and you will get errors.

[root@node1 ~]# mkdir /var/lib/ldap/accesslog
[root@node1 ~]# mkdir /var/lib/ldap
[root@node1 ~]# mkdir /var/run/slapd

Step9.

Login to node2 and repeat the above steps as done on the provider. Configure your slapd.conf on your consumer as per here: 2.3.2 slapd.conf Slave delta-syncrepl Openldap2.3

LDAP should not be running at this stage; clear any previous database and obtain your domain SID as per section 3.1 Provisioning Database

We now need to create database file, containing the nessasry entries as provided here: 3.2. Preload LDIF

Take care in this section, note to create the additional directories needed as we have 2 seperate databases, each of these database directories needs its own DB_CONFIG file, remember that ldap must not be running. 3.3 LDAP Population

Common issue.

You may run into this problem when running slaptest, we need to add our base dn, start LDAP and this error will then go away; you also may have forgotten to create a directory specified in the slapd.conf after compiling LDAP.

[root@node1 OSBACKUP-8.2.07]# slaptest
bdb_db_open: db_open(/var/lib/ldap/accesslog/id2entry.bdb) failed: No such file or directory (2)
bdb(cn=accesslog): Unknown locker ID: 0
backend_startup_one: bi_db_open failed! (2)
slap_startup failed (test would succeed using the -u switch)


Step10.

Now it is time to start the LDAP daemon as per section [3.4 starting LDAP]

2.2. slapd.conf Master slurpd

This is the original method for replicating the database to slave ldap servers. We are using the slurpd which has been around for a long time and proven itself to be stable.

This configuration file should work on any version of Openldap.

# /etc/openldap/slapd.conf
# using slurpd
# LDAP Master

include     /etc/openldap/schema/core.schema
include     /etc/openldap/schema/cosine.schema
include     /etc/openldap/schema/inetorgperson.schema
include     /etc/openldap/schema/nis.schema
include     /etc/openldap/schema/samba.schema

pidfile     /var/run/slapd/slapd.pid
argsfile    /var/run/slapd/slapd.args

database    bdb
suffix       "dc=differentialdesign,dc=org"
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager
directory   /var/lib/ldap

replica  host=node2.differentialdesign.org:389
           suffix="dc=differentialdesign,dc=org"
           binddn="cn=syncuser,dc=differentialdesign,dc=org"
           bindmethod=simple credentials=SyncUser

replogfile  /var/lib/ldap/replogfile

access to attrs=userPassword
        by self write
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read
        by * auth
 
access to attrs=sambaLMPassword,sambaNTPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read

access to *
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read
        by * read

# Indices to maintain
index objectClass           eq
index cn                    pres,sub,eq
index sn                    pres,sub,eq
index uid                   pres,sub,eq
index displayName           pres,sub,eq
index uidNumber             eq
index gidNumber             eq
index memberUID             eq
index sambaSID              eq
index sambaPrimaryGroupSID  eq
index sambaDomainName       eq
index default               sub

2.2.1. slapd.conf Master syncrepl Openldap2.2

This is the slapd.conf master ldap file; we are using syncrepl instead of slurpd which is the traditional method.

This configuration file is specifically designed for openldap 2.2 and supports syncrepl refreshOnly mode.

# slapd.conf Master syncrepl Openldap2.2
# Provider

include     /etc/openldap/schema/core.schema
include     /etc/openldap/schema/cosine.schema
include     /etc/openldap/schema/inetorgperson.schema
include     /etc/openldap/schema/nis.schema
include     /etc/openldap/schema/samba.schema

pidfile     /var/run/slapd/slapd.pid
argsfile    /var/run/slapd/slapd.args

database    bdb
suffix      "dc=differentialdesign,dc=org"
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager
directory   /var/lib/ldap

access to attrs=userPassword
        by self write
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read
        by * auth

access to attrs=sambaLMPassword,sambaNTPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read

access to *
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
        by dn="cn=syncuser,dc=differentialdesign,dc=org" read
        by * read

# Indices to maintain

index objectClass           eq
index cn                    pres,sub,eq
index sn                    pres,sub,eq
index uid                   pres,sub,eq
index displayName           pres,sub,eq
index uidNumber             eq
index gidNumber             eq
index memberUID             eq
index sambaSID              eq
index sambaPrimaryGroupSID  eq
index sambaDomainName       eq
index default               sub

2.2.2. slapd.conf Master delta-syncrepl Openldap2.3

This configuration file is designed to support Openldap’s newest features. We will be using delta-syncrepl which supports refreshAndPersist with performance similar to that of slurpd.


The below slapd.conf will only run on Openldap 2.3.

Take note of the “modulepath /usr/local/libexec/openldap” in the below file, you will need to change this to where you have your modules located.

#slapd.conf Master delta syncrepl Openldap2.3
#path: /usr/local/etc/openldap/slapd.conf
#provider

include     /usr/local/etc/openldap/schema/core.schema
include     /usr/local/etc/openldap/schema/cosine.schema
include     /usr/local/etc/openldap/schema/inetorgperson.schema
include     /usr/local/etc/openldap/schema/nis.schema
include     /usr/local/etc/openldap/schema/samba.schema

#If your slapd was configured with dynamic module support, and your backends and overlays are not statically compiled, you will need these module statements.
modulepath /usr/local/libexec/openldap
moduleload syncprov.la
moduleload accesslog.la
moduleload back_bdb.la

pidfile     /var/run/slapd/slapd.pid
argsfile    /var/run/slapd/slapd.args

# Accesslog database definitions
database    bdb
suffix      cn=accesslog
directory   /var/lib/ldap/accesslog
rootdn      cn=accesslog
index default eq
index entryCSN,objectClass,reqEnd,reqResult,reqStart

overlay syncprov
syncprov-nopresent TRUE
syncprov-reloadhint TRUE

# Samba primary database
database    bdb
suffix      "dc=differentialdesign,dc=org"
directory   /var/lib/ldap
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager
index entryCSN eq
index entryUUID eq

overlay syncprov
syncprov-checkpoint 1000 60

# accesslog overlay definitions for primary database
overlay accesslog
logdb cn=accesslog
logops writes
logsuccess TRUE
# scan the accesslog DB every day, and purge entries older than 7 days
logpurge 07+00:00 01+00:00

# give syncuser DN limitless searches
limits dn.exact="cn=syncuser,dc=differentialdesign,dc=org" time.soft=unlimited time.hard=unlimited size.soft=unlimited size.hard=unlimited

access to attrs=userPassword
       by self write
       by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
       by dn="cn=syncuser,dc=differentialdesign,dc=org" read
       by * auth

access to attrs=sambaLMPassword,sambaNTPassword
       by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
       by dn="cn=syncuser,dc=differentialdesign,dc=org" read

access to *
       by dn="cn=sambaadmin,dc=differentialdesign,dc=org" write
       by dn="cn=syncuser,dc=differentialdesign,dc=org" read
       by * read

# Indices to maintain
index objectClass             eq
index cn                      pres,sub,eq
index sn                      pres,sub,eq
index uid                     pres,sub,eq
index displayName             pres,sub,eq
index uidNumber               eq
index gidNumber               eq
index memberUID               eq
index sambaSID                eq
index sambaPrimaryGroupSID    eq
index sambaDomainName         eq
index default                 sub

2.3. slapd.conf Slave slurpd

This is the original method for replicating the database to slave ldap servers. We are using the slurpd which has been around for a long time and proven itself to be stable.

This configuration file should work on any version of openldap.

# /etc/openldap/slapd.conf
# using slurpd
# LDAP Slave

include     /etc/openldap/schema/core.schema
include     /etc/openldap/schema/cosine.schema
include     /etc/openldap/schema/inetorgperson.schema
include     /etc/openldap/schema/nis.schema
include     /etc/openldap/schema/samba.schema

pidfile     /var/run/slapd/slapd.pid
argsfile    /var/run/slapd/slapd.args

database    bdb
suffix      "dc=differentialdesign,dc=org"
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager

access to attrs=userPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * auth

access to attrs=sambaLMPassword,sambaNTPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write

access to *
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * read

updatedn    cn=syncuser,dc=differentialdesign,dc=org

updateref   ldap://node1.differentialdesign.org

directory   /var/lib/ldap

# Indices to maintain
index objectClass                          eq
index cn                                   pres,sub,eq
index sn                                   pres,sub,eq
index uid                                  pres,sub,eq
index displayName                          pres,sub,eq
index uidNumber                            eq
index gidNumber                            eq
index memberUID                            eq
index sambaSID                             eq
index sambaPrimaryGroupSID                 eq
index sambaDomainName                      eq
index default                              sub

2.3.1. slapd.conf Slave syncrepl Openldap2.2

This is the configuration file for openldap version 2.2 using the syncrepl method refreshOnly.


# slapd.conf Slave syncrepl Openldap2.2
# LDAP Consumer
 
include     /etc/openldap/schema/core.schema
include     /etc/openldap/schema/cosine.schema
include     /etc/openldap/schema/inetorgperson.schema
include     /etc/openldap/schema/nis.schema
include     /etc/openldap/schema/samba.schema

pidfile     /var/run/slapd/slapd.pid
argsfile    /var/run/slapd/slapd.args
 
database    bdb
suffix      "dc=differentialdesign,dc=org"
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager
directory   /var/lib/ldap

syncrepl
   rid=0
       provider=ldap://node1.differentialdesign.org:389
       binddn="cn=syncuser,dc=differentialdesign,dc=org"
       bindmethod=simple
       credentials=SyncUser
       searchbase="dc=differentialdesign,dc=org"
       filter="(objectClass=*)"
       attrs="*"
       schemachecking=off
       scope=sub
       type=refreshOnly
       interval=00:06:00:00 

access to attrs=userPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * auth
 
access to attrs=sambaLMPassword,sambaNTPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write

access to *
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * read

# Indices to maintain
index objectClass           eq
index cn                    pres,sub,eq
index sn                    pres,sub,eq
index uid                   pres,sub,eq
index displayName           pres,sub,eq
index uidNumber             eq
index gidNumber             eq
index memberUID             eq
index sambaSID              eq
index sambaPrimaryGroupSID  eq
index sambaDomainName       eq
index default               sub

2.3.2. slapd.conf Slave delta-syncrepl Openldap2.3

# slapd.conf delta synrepl Openldap2.3
# LDAP Consumer
 
include     /usr/local/etc/openldap/schema/core.schema
include     /usr/local/etc/openldap/schema/cosine.schema
include     /usr/local/etc/openldap/schema/inetorgperson.schema
include     /usr/local/etc/openldap/schema/nis.schema
include     /usr/local/etc/openldap/schema/samba.schema

modulepath /usr/local/libexec/openldap
moduleload back_bdb.la

pidfile     /usr/local/var/run/slapd/slapd.pid
argsfile    /usr/local/var/run/slapd/slapd.args
 
database    bdb
suffix      "dc=differentialdesign,dc=org"
directory   /usr/local/etc/openldap-data
rootdn      "cn=Manager,dc=differentialdesign,dc=org"
rootpw      Manager

# syncrepl directives
syncrepl  rid=0
       provider=ldap://node1.differentialdesign.org:389
       bindmethod=simple
       binddn="cn=syncuser,dc=differentialdesign,dc=org"
       credentials=SyncUser
       searchbase="dc=differentialdesign,dc=org"
       logbase="cn=accesslog"
       logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
       schemachecking=on
       type=refreshAndPersist
       retry="60 +"
       syncdata=accesslog
 
access to attrs=userPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * auth

access to attrs=sambaLMPassword,sambaNTPassword
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write

access to *
        by dn="cn=sambaadmin,dc=differentialdesign,dc=org" read
        by dn="cn=syncuser,dc=differentialdesign,dc=org" write
        by * read

updateref   ldap://node1.differentialdesign.org

# Indices to maintain
index objectClass           eq
index cn                    pres,sub,eq
index sn                    pres,sub,eq
index uid                   pres,sub,eq
index displayName           pres,sub,eq
index uidNumber             eq
index gidNumber             eq
index memberUID             eq
index sambaSID              eq
index sambaPrimaryGroupSID  eq
index sambaDomainName       eq
index default               sub

2.4. ldap.conf Master

You will notice below in the host options that we use both IP addresses of the Primary and Secondary LDAP database servers. This serves as a failover option if the local LDAP database is inaccessible. The same applies for the Slave LDAP configuration; 2.4: ldap.conf Slave


#/etc/ldap.conf
# LDAP Master

host    node1.differentialdesign.org node2.differentialdesign.org
base    dc=differentialdesign,dc=org
binddn  cn=Manager,dc=differentialdesign,dc=org
bindpw  Manager 

bind_policy soft 
pam_password exop

nss_base_passwd ou=People,ou=Users,dc=differentialdesign,dc=org?one
nss_base_shadow ou=People,ou=Users,dc=differentialdesign,dc=org?one
nss_base_passwd ou=Computers,ou=Users,dc=differentialdesign,dc=org?one
nss_base_shadow ou=Computers,ou=Users,dc=differentialdesign,dc=org?one
nss_base_group  ou=Groups,dc=differentialdesign,dc=org?one
ssl     no

2.5. ldap.conf Slave

#/etc/ldap.conf
# LDAP Slave

host    node2.differentialdesign.org node1.differentialdesign.org
base    dc=differentialdesign,dc=org
binddn  cn=Manager,dc=differentialdesign,dc=org
bindpw  Manager

bind_policy soft 
pam_password exop

nss_base_passwd ou=People,ou=Users,dc=differentialdesign,dc=org?one
nss_base_shadow ou=People,ou=Users,dc=differentialdesign,dc=org?one
nss_base_passwd ou=Computers,ou=Users,dc=differentialdesign,dc=org?one
nss_base_shadow ou=Computers,ou=Users,dc=differentialdesign,dc=org?one
nss_base_group  ou=Groups,dc=differentialdesign,dc=org?one
ssl     no

2.6. /etc/nsswitch.conf

You can see how unix will resolve the users and groups; it will first check system files, if user or group is not found it will then use ldap.

You can see the hosts options uses DNS and WINS; the same also applies.

On both nodes edit your nsswitch.conf as follows; leave all other settings as defaults.

#/etc/nsswitch.conf

passwd:         files ldap
shadow:         files ldap
group:          files ldap

hosts:          files dns wins
networks:       files dns