Difference between revisions of "OpenLDAP"

From ArchWiki
Jump to: navigation, search
(→‎Configuration)
m (on new setups, the deamon needs to be started once for saving the settings)
(48 intermediate revisions by 7 users not shown)
Line 1: Line 1:
 
[[Category:Networking]]
 
[[Category:Networking]]
 
[[ru:openLDAP]]
 
[[ru:openLDAP]]
 +
{{Related articles start}}
 +
{{Related|LDAP Authentication}}
 +
{{Related|LDAP Hosts}}
 +
{{Related articles end}}
  
−
{{Out of date|slapd.conf(5) is deprecated; use slapd-config(5)}}
+
OpenLDAP is an open-source implementation of the LDAP protocol. An LDAP server basically is a non-relational database which is optimised for accessing, but not writing, data. It is mainly used as an address book (for e.g. email clients) or authentication backend to various services (such as Samba, where it is used to emulate a domain controller, or [[LDAP Authentication|Linux system authentication]], where it replaces {{ic|/etc/passwd}}) and basically holds the user data.
  
−
OpenLDAP, LDAP & Directory services are an enormous topic. Configuration is therefore complex. This page is a starting point for a basic OpenLDAP installation and a sanity check.  
+
Commands related to OpenLDAP that begin with {{ic|ldap}} (like {{ic|ldapsearch}}) are client-side utilities, while commands that begin with {{ic|slap}} (like {{ic|slapcat}}) are server-side.
  
−
If you are totally new to those concepts, [http://www.brennan.id.au/20-Shared_Address_Book_LDAP.html this] is an good introduction that is easy to understand and that will get you started, even if you are new to everything LDAP.
+
Directory services are an enormous topic. Configuration can therefore be complex. This page is a starting point for a basic OpenLDAP installation and a sanity check. If you are totally new to those concepts, [http://www.brennan.id.au/20-Shared_Address_Book_LDAP.html this] is an good introduction that is easy to understand and that will get you started, even if you are new to everything LDAP.
  
 
== Installation ==
 
== Installation ==
Line 18: Line 22:
 
{{Note|If you already have an OpenLDAP database on your machine, remove it by deleting everything inside {{ic|/var/lib/openldap/openldap-data/}}.}}
 
{{Note|If you already have an OpenLDAP database on your machine, remove it by deleting everything inside {{ic|/var/lib/openldap/openldap-data/}}.}}
  
−
First prepare the run directory:
+
The server configuration file is located at {{ic|/etc/openldap/slapd.conf}}.
−
# mkdir /run/openldap
 
−
# chown ldap:ldap /run/openldap
 
−
 
 
−
Next we prepare the server configuration file: {{ic|/etc/openldap/slapd.conf}}.
 
  
 
Edit the suffix and rootdn. The suffix typically is your domain name but it does not have to be. It depends on how you use your directory. We will use ''example'' for the domain name, and ''com'' for the tld. The rootdn is your LDAP administrator's name (we'll use ''root'' here).
 
Edit the suffix and rootdn. The suffix typically is your domain name but it does not have to be. It depends on how you use your directory. We will use ''example'' for the domain name, and ''com'' for the tld. The rootdn is your LDAP administrator's name (we'll use ''root'' here).
Line 31: Line 31:
  
 
Now we delete the default root password and create a strong one:
 
Now we delete the default root password and create a strong one:
−
  # sed -i "/rootpw/ d" slapd.conf #find the line with rootpw and delete it
+
  # sed -i "/rootpw/ d" /etc/openldap/slapd.conf #find the line with rootpw and delete it
−
  # echo "rootpw    $(slappasswd)" >> slapd.conf  #add a line which includes the hashed password output from slappasswd
+
  # echo "rootpw    $(slappasswd)" >> /etc/openldap/slapd.conf  #add a line which includes the hashed password output from slappasswd
  
 
You will likely want to add some typically used [http://www.openldap.org/doc/admin24/schema.html schemas] to the top of {{ic|slapd.conf}}:
 
You will likely want to add some typically used [http://www.openldap.org/doc/admin24/schema.html schemas] to the top of {{ic|slapd.conf}}:
Line 54: Line 54:
 
  # chown ldap:ldap /var/lib/openldap/openldap-data/DB_CONFIG
 
  # chown ldap:ldap /var/lib/openldap/openldap-data/DB_CONFIG
  
−
Perform an intial index after you populate your directory:
+
{{Note|With OpenLDAP 2.4 the configuration of {{ic|slapd.config}} is deprecated. From this version on all configuration settings are stored in {{ic|/etc/openldap/slapd.d/}}.}}
 +
 
 +
To store the recent changes in {{ic|slapd.conf}} to the new {{ic|slapd-config}} configuration settings, we have to delete the old configuration files first:
 +
 
 +
# rm -rf /etc/openldap/slapd.d/*
 +
 
 +
 +
(if you do not have a database yet, you might need to create one by starting and stopping the {{ic|slapd.service}} [[systemd#Using units|using systemd]] )
 +
 
 +
 
 +
Then we generate the new configuration with:
 +
 
 +
# slaptest -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d/
 +
 
 +
This last command has to be run every time you change {{ic|slapd.conf}}.
 +
 
 +
Check if everything succeeded and finally start the slapd daemon.
 +
 
 +
{{note|Index the directory after you populate it. You should stop slapd before doing this.
 
  # slapindex
 
  # slapindex
 
  # chown ldap:ldap /var/lib/openldap/openldap-data/*
 
  # chown ldap:ldap /var/lib/openldap/openldap-data/*
 +
}}
  
−
Finally you can start the slapd daemon with {{ic|slapd.service}} [[systemd#Using units|using systemd]].
+
=== The client ===
 +
The client config file is located at {{ic|/etc/openldap/ldap.conf}}.  
  
−
If you want to change the port the server should listen on or if you want to use SSL, you will need to edit {{ic|/etc/conf.d/slapd}}. See [[#OpenLDAP over TLS]] for more information.
+
It is quite simple: you'll only have to alter {{ic|BASE}} to reflect the suffix of the server, and {{ic|URI}} to reflect the address of the server, like:
  
−
=== The client ===
+
{{hc|/etc/openldap/ldap.conf|2=
−
The client is usually not such a big deal, just keep in mind that your apps that require LDAP auth use it, so if something goes wrong with LDAP, do not waste your time with the app, start debugging the client instead.
+
BASE            dc=example,dc=com
 +
URI            ldap://localhost
 +
}}
  
−
The client config file is located at /etc/openldap/ldap.conf
+
If you decide to use SSL:
−
It is actually very simple.
 
  
−
If you decide to use SSL:
+
* The protocol (ldap or ldaps) in the {{ic|URI}} entry has to conform with the slapd configuration  
−
* The protocol (ldap or ldaps) in the URI entry has to conform with the slapd configuration  
+
* If you decide to use self-signed certificates, add a {{ic|TLS_REQCERT allow}} line to {{ic|ldap.conf}}
−
* If you decide to use self-signed certificates, you have to add them to TLS_CACERT
 
  
 
=== Test your new OpenLDAP installation ===
 
=== Test your new OpenLDAP installation ===
  
 
This is easy, just run the command below:
 
This is easy, just run the command below:
−
  ldapsearch -x -b "" -s base '(objectclass=*)' namingContexts
+
  $ ldapsearch -x '(objectclass=*)'
  
−
Or more explicitly using the example configuration we had above:
+
Or authenticating as the rootdn (replacing {{ic|-x}} by {{ic|-D <user> -W}}), using the example configuration we had above:
−
  ldapsearch -v -W -D "cn=root,dc=example,dc=com" -b "" -x -s base '(objectclass=*)' namingContexts
+
  $ ldapsearch -D "cn=root,dc=example,dc=com" -W '(objectclass=*)'
  
 
Now you should see some information about your database.
 
Now you should see some information about your database.
Line 85: Line 105:
 
{{Note|[http://web.archive.org/web/20130211222328/http://www.openldap.org/pub/ksoper/OpenLDAP_TLS.html#4.0 upstream documentation] is much more useful/complete than this section}}
 
{{Note|[http://web.archive.org/web/20130211222328/http://www.openldap.org/pub/ksoper/OpenLDAP_TLS.html#4.0 upstream documentation] is much more useful/complete than this section}}
  
−
If you access the Openldap server over the network and especially if you have sensitive data stored on the server you run the risk of someone sniffing your data which is sent clear-text. The next part will guide you on how to setup an SSL connection between the LDAP server and the client so the data will be sent encrypted.
+
If you access the OpenLDAP server over the network and especially if you have sensitive data stored on the server you run the risk of someone sniffing your data which is sent clear-text. The next part will guide you on how to setup an SSL connection between the LDAP server and the client so the data will be sent encrypted.
 +
 
 +
In order to use TLS, you must have a certificate. For testing purposes, a ''self-signed'' certificate will suffice. To learn more about certificates, see [[OpenSSL]].
  
−
In order to use TLS, we must first create a certificate. You can have a certificate signed, or create your own Certificate Authority (CA), but for our purposed, a self-signed certificate will suffice.
 
 
{{Warning|OpenLDAP cannot use a certificate that has a password associated to it.}}
 
{{Warning|OpenLDAP cannot use a certificate that has a password associated to it.}}
  
 
==== Create a self-signed certificate ====
 
==== Create a self-signed certificate ====
 
To create a ''self-signed'' certificate, type the following:
 
To create a ''self-signed'' certificate, type the following:
−
{{bc|openssl req -new -x509 -nodes -out slapdcert.pem -keyout slapdkey.pem -days 365}}
+
$ openssl req -new -x509 -nodes -out slapdcert.pem -keyout slapdkey.pem -days 365
  
 
You will be prompted for information about your LDAP server. Much of the information can be left blank. The most important information is the common name. This must be set to the DNS name of your LDAP server. If your LDAP server's IP address resolves to example.org but its server certificate shows a CN of bad.example.org, LDAP clients will reject the certificate and will be unable to negotiate TLS connections (apparently the results are wholly unpredictable).
 
You will be prompted for information about your LDAP server. Much of the information can be left blank. The most important information is the common name. This must be set to the DNS name of your LDAP server. If your LDAP server's IP address resolves to example.org but its server certificate shows a CN of bad.example.org, LDAP clients will reject the certificate and will be unable to negotiate TLS connections (apparently the results are wholly unpredictable).
  
−
Now that the certificate files have been created copy them to {{ic|/etc/openldap/ssl/}} (if this directory doesn't exist create it) and secure them.  
+
Now that the certificate files have been created copy them to {{ic|/etc/openldap/ssl/}} (create this directory if it doesn't exist) and secure them.  
−
'''IMPORTANT:''' slapdcert.pem must be world readable because it contains the public key. slapdkey.pem on the other hand should only be readable for the ldap user for security reasons:
+
{{ic|slapdcert.pem}} must be world readable because it contains the public key. {{ic|slapdkey.pem}} on the other hand should only be readable for the ldap user for security reasons:
−
{{bc|
+
# mv slapdcert.pem slapdkey.pem /etc/openldap/ssl/
−
cp slapdcert.pem slapdkey.pem /etc/openldap/ssl/
+
# chmod -R 744 /etc/openldap/ssl/
−
chown ldap slapdkey.pem
+
# chmod 400 /etc/openldap/ssl/slapdkey.pem
−
chmod 400 slapdkey.pem
+
# chmod 444 /etc/openldap/ssl/slapdcert.pem
−
chmod 444 slapdcert.pem
+
# chown ldap /etc/openldap/ssl/slapdkey.pem
−
}}
+
 
 +
The {{ic|/etc/openldap/slapd.d}} folder and it's files should be owned by {{ic|ldap}} user and group:
 +
# chown -R ldap:ldap /etc/openldap/slapd.d/
  
 
==== Configure slapd for SSL ====
 
==== Configure slapd for SSL ====
Line 109: Line 132:
 
{{bc|
 
{{bc|
 
# Certificate/SSL Section
 
# Certificate/SSL Section
−
TLSCipherSuite HIGH:MEDIUM:+SSLv2
+
TLSCipherSuite HIGH:MEDIUM:-SSLv2
 
TLSCertificateFile /etc/openldap/ssl/slapdcert.pem
 
TLSCertificateFile /etc/openldap/ssl/slapdcert.pem
 
TLSCertificateKeyFile /etc/openldap/ssl/slapdkey.pem
 
TLSCertificateKeyFile /etc/openldap/ssl/slapdkey.pem
Line 119: Line 142:
  
 
==== Start slapd with SSL ====
 
==== Start slapd with SSL ====
−
In order to tell OpenLDAP to start using encryption, edit /etc/conf.d/slapd, uncomment the SLAPD_SERVICES line and set it to the following:
+
You will have to edit {{ic|slapd.service}} to change to protocol slapd listens on.
−
{{bc|1=SLAPD_SERVICES="ldaps:///"}}
+
 
−
Localhost connections don't need to use SSL so you can use this instead:
+
First, disable {{ic|slapd.service}} if it's enabled.
−
{{bc|1=SLAPD_SERVICES="ldap://127.0.0.1 ldaps:///:}}
+
 
 +
systemctl stop slapd.service
 +
 
 +
Then, copy the stock service to {{ic|/etc/systemd/system/}}:
 +
# cp /usr/lib/systemd/system/slapd.service /etc/systemd/system/
  
 +
Edit it, and add change {{ic|ExecStart}} to:
 +
{{hc|/etc/systemd/system/slapd.service|<nowiki>
 +
ExecStart=/usr/bin/slapd -u ldap -g ldap -h "ldaps:///"</nowiki>}}
  
−
'''IMPORTANT:''' If you created a self-signed certificate above be sure to add the following line to /etc/openldap/ldap.conf or you won't be able connect to the server to test it:
+
Localhost connections don't need to use SSL. So, if you want to access the server locally you should change the {{ic|ExecStart}} line to:
 +
ExecStart=/usr/bin/slapd -u ldap -g ldap -h "ldap://127.0.0.1 ldaps:///"
  
−
  TLS_REQCERT allow
+
Then reenable and start it:
 +
  # systemctl daemon-reload
 +
# systemctl restart slapd.service
  
−
Finally restart the server.
+
If {{ic|slapd}} started successfully you can enable it with:
 +
# systemctl enable slapd.service
 +
 
 +
{{Note|If you created a self-signed certificate above, be sure to add {{ic|TLS_REQCERT allow}} to {{ic|/etc/openldap/ldap.conf}} on the client, or it won't be able connect to the server.}}
  
 
== Next Steps ==
 
== Next Steps ==
  
−
You now have a basic ldap installation. The step is to design your directory. The design is heavily dependent on what you are using it for. If you are new to ldap, consider starting with a directory design recommended by the specific client services that will use the directory (PAM, Postfix, etc).
+
You now have a basic LDAP installation. The next step is to design your directory. The design is heavily dependent on what you are using it for. If you are new to LDAP, consider starting with a directory design recommended by the specific client services that will use the directory (PAM, [[Postfix]], etc).
  
 
A directory for system authentication is the [[LDAP Authentication]] article.
 
A directory for system authentication is the [[LDAP Authentication]] article.
 +
 +
A nice web frontend is [[phpLDAPadmin]].
  
 
== Troubleshooting ==
 
== Troubleshooting ==
 +
 +
=== Client Authentication Checking ===
 +
If you can't connect to your server for non-secure authentication
 +
 +
$ ldapsearch -x -H ldap://ldaservername:389 -D cn=Manager,dc=example,dc=exampledomain
 +
 +
and for TLS secured authentication with:
 +
 +
$ ldapsearch -x -H ldaps://ldaservername:636 -D cn=Manager,dc=example,dc=exampledomain
 +
 +
=== LDAP Sserver Stops Suddenly ===
 +
 
If you notice that slapd seems to start but then stops, you may have a permission issue with the ldap datadir. Try running:
 
If you notice that slapd seems to start but then stops, you may have a permission issue with the ldap datadir. Try running:
  
Line 145: Line 195:
  
 
== See Also ==
 
== See Also ==
−
* http://www.openldap.org/doc/admin24/
+
* [http://www.openldap.org/doc/admin24/ Official OpenLDAP Software 2.4 Administrator's Guide]
 
* [[phpLDAPadmin]] is a web interface tool in the style of phpMyAdmin.
 
* [[phpLDAPadmin]] is a web interface tool in the style of phpMyAdmin.
−
* {{AUR|apachedirectorystudio2}} from the [[Arch User Repository]] is an Eclipse-based LDAP viewer. Works perfect for OpenLDAP installations.
+
* [[LDAP Authentication]]
 +
* {{AUR|apachedirectorystudio2}} from the [[Arch User Repository]] is an Eclipse-based LDAP viewer. Works perfect with OpenLDAP installations.

Revision as of 15:56, 27 March 2014

Related articles

OpenLDAP is an open-source implementation of the LDAP protocol. An LDAP server basically is a non-relational database which is optimised for accessing, but not writing, data. It is mainly used as an address book (for e.g. email clients) or authentication backend to various services (such as Samba, where it is used to emulate a domain controller, or Linux system authentication, where it replaces /etc/passwd) and basically holds the user data.

Commands related to OpenLDAP that begin with ldap (like ldapsearch) are client-side utilities, while commands that begin with slap (like slapcat) are server-side.

Directory services are an enormous topic. Configuration can therefore be complex. This page is a starting point for a basic OpenLDAP installation and a sanity check. If you are totally new to those concepts, this is an good introduction that is easy to understand and that will get you started, even if you are new to everything LDAP.

Installation

OpenLDAP contains both a LDAP server and client. Install it with the package openldap, available in the official repositories.

Configuration

The server

Note: If you already have an OpenLDAP database on your machine, remove it by deleting everything inside /var/lib/openldap/openldap-data/.

The server configuration file is located at /etc/openldap/slapd.conf.

Edit the suffix and rootdn. The suffix typically is your domain name but it does not have to be. It depends on how you use your directory. We will use example for the domain name, and com for the tld. The rootdn is your LDAP administrator's name (we'll use root here). 

suffix     "dc=example,dc=com"
rootdn     "cn=root,dc=example,dc=com"

Now we delete the default root password and create a strong one: 

# sed -i "/rootpw/ d" /etc/openldap/slapd.conf #find the line with rootpw and delete it
# echo "rootpw    $(slappasswd)" >> /etc/openldap/slapd.conf  #add a line which includes the hashed password output from slappasswd

You will likely want to add some typically used schemas to the top of slapd.conf: 

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

You will likely want to add some typically used indexes to the bottom of slapd.conf: 

index   uid             pres,eq
index   mail            pres,sub,eq
index   cn              pres,sub,eq
index   sn              pres,sub,eq
index   dc              eq

Now prepare the database directory. You will need to copy the default config file and set the proper ownership: 

# cp /etc/openldap/DB_CONFIG.example /var/lib/openldap/openldap-data/DB_CONFIG
# chown ldap:ldap /var/lib/openldap/openldap-data/DB_CONFIG
Note: With OpenLDAP 2.4 the configuration of slapd.config is deprecated. From this version on all configuration settings are stored in /etc/openldap/slapd.d/.

To store the recent changes in slapd.conf to the new slapd-config configuration settings, we have to delete the old configuration files first: 

# rm -rf /etc/openldap/slapd.d/*


(if you do not have a database yet, you might need to create one by starting and stopping the slapd.service using systemd )


Then we generate the new configuration with: 

# slaptest -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d/

This last command has to be run every time you change slapd.conf.

Check if everything succeeded and finally start the slapd daemon.

Note: Index the directory after you populate it. You should stop slapd before doing this. 
# slapindex
# chown ldap:ldap /var/lib/openldap/openldap-data/*

The client

The client config file is located at /etc/openldap/ldap.conf.

It is quite simple: you'll only have to alter BASE to reflect the suffix of the server, and URI to reflect the address of the server, like: 

/etc/openldap/ldap.conf
BASE            dc=example,dc=com
URI             ldap://localhost

If you decide to use SSL:

  • The protocol (ldap or ldaps) in the URI entry has to conform with the slapd configuration
  • If you decide to use self-signed certificates, add a TLS_REQCERT allow line to ldap.conf

Test your new OpenLDAP installation

This is easy, just run the command below: 

$ ldapsearch -x '(objectclass=*)'

Or authenticating as the rootdn (replacing -x by -D <user> -W), using the example configuration we had above: 

$ ldapsearch -D "cn=root,dc=example,dc=com" -W '(objectclass=*)'

Now you should see some information about your database.

OpenLDAP over TLS

Note: upstream documentation is much more useful/complete than this section

If you access the OpenLDAP server over the network and especially if you have sensitive data stored on the server you run the risk of someone sniffing your data which is sent clear-text. The next part will guide you on how to setup an SSL connection between the LDAP server and the client so the data will be sent encrypted.

In order to use TLS, you must have a certificate. For testing purposes, a self-signed certificate will suffice. To learn more about certificates, see OpenSSL.

Warning: OpenLDAP cannot use a certificate that has a password associated to it.

Create a self-signed certificate

To create a self-signed certificate, type the following: 

$ openssl req -new -x509 -nodes -out slapdcert.pem -keyout slapdkey.pem -days 365

You will be prompted for information about your LDAP server. Much of the information can be left blank. The most important information is the common name. This must be set to the DNS name of your LDAP server. If your LDAP server's IP address resolves to example.org but its server certificate shows a CN of bad.example.org, LDAP clients will reject the certificate and will be unable to negotiate TLS connections (apparently the results are wholly unpredictable).

Now that the certificate files have been created copy them to /etc/openldap/ssl/ (create this directory if it doesn't exist) and secure them. slapdcert.pem must be world readable because it contains the public key. slapdkey.pem on the other hand should only be readable for the ldap user for security reasons: 

# mv slapdcert.pem slapdkey.pem /etc/openldap/ssl/
# chmod -R 744 /etc/openldap/ssl/
# chmod 400 /etc/openldap/ssl/slapdkey.pem
# chmod 444 /etc/openldap/ssl/slapdcert.pem
# chown ldap /etc/openldap/ssl/slapdkey.pem

The /etc/openldap/slapd.d folder and it's files should be owned by ldap user and group: 

# chown -R ldap:ldap /etc/openldap/slapd.d/

Configure slapd for SSL

Edit the daemon configuration file (/etc/openldap/slapd.conf) to tell LDAP where the certificate files reside by adding the following lines: 

# Certificate/SSL Section
TLSCipherSuite HIGH:MEDIUM:-SSLv2
TLSCertificateFile /etc/openldap/ssl/slapdcert.pem
TLSCertificateKeyFile /etc/openldap/ssl/slapdkey.pem

The TLSCipherSuite specifies a list of OpenSSL ciphers from which slapd will choose when negotiating TLS connections, in decreasing order of preference. In addition to those specific ciphers, you can use any of the wildcards supported by OpenSSL. NOTE: HIGH, MEDIUM, and +SSLv2 are all wildcards.

Note: To see which ciphers are supported by your local OpenSSL installation, type the following: openssl ciphers -v ALL

Start slapd with SSL

You will have to edit slapd.service to change to protocol slapd listens on.

First, disable slapd.service if it's enabled. 

systemctl stop slapd.service

Then, copy the stock service to /etc/systemd/system/: 

# cp /usr/lib/systemd/system/slapd.service /etc/systemd/system/

Edit it, and add change ExecStart to: 

/etc/systemd/system/slapd.service
ExecStart=/usr/bin/slapd -u ldap -g ldap -h "ldaps:///"

Localhost connections don't need to use SSL. So, if you want to access the server locally you should change the ExecStart line to: 

ExecStart=/usr/bin/slapd -u ldap -g ldap -h "ldap://127.0.0.1 ldaps:///"

Then reenable and start it: 

# systemctl daemon-reload
# systemctl restart slapd.service

If slapd started successfully you can enable it with: 

# systemctl enable slapd.service
Note: If you created a self-signed certificate above, be sure to add TLS_REQCERT allow to /etc/openldap/ldap.conf on the client, or it won't be able connect to the server.

Next Steps

You now have a basic LDAP installation. The next step is to design your directory. The design is heavily dependent on what you are using it for. If you are new to LDAP, consider starting with a directory design recommended by the specific client services that will use the directory (PAM, Postfix, etc).

A directory for system authentication is the LDAP Authentication article.

A nice web frontend is phpLDAPadmin.

Troubleshooting

Client Authentication Checking

If you can't connect to your server for non-secure authentication 

$ ldapsearch -x -H ldap://ldaservername:389 -D cn=Manager,dc=example,dc=exampledomain

and for TLS secured authentication with: 

$ ldapsearch -x -H ldaps://ldaservername:636 -D cn=Manager,dc=example,dc=exampledomain

LDAP Sserver Stops Suddenly

If you notice that slapd seems to start but then stops, you may have a permission issue with the ldap datadir. Try running: 

# chown ldap:ldap /var/lib/openldap/openldap-data/*

to allow slapd write access to its data directory as the user "ldap"

See Also

Retrieved from "https://wiki.archlinux.org/index.php?title=OpenLDAP&oldid=307330"