If you are looking at this guide to install your production servers/ IDPs, please consult

The following guide is intended for the workshop use only.

Install the OpenLDAP Server on Ubuntu 18.04 LTS with eduPerson Schema

It is assumed that you have already install your IDP Ubuntu server with a public IP address and a Domain Name (

On your IDP server,

sudo apt-get update
sudo apt-get install slapd ldap-utils gnutls-bin ssl-cert vim

When it prompts for a password enter iam@2018 In order to access some additional prompts that we need, we'll reconfigure the package after installation. To do so, type:

sudo dpkg-reconfigure slapd

Answer the prompts appropriately, using the information below as a starting point:

  • Omit OpenLDAP server configuration? No (we want an initial database and configuration)
  • DNS domain name: (use the server's domain name, minus the hostname. This will be used to create the base entry for the information tree)
  • Organization name: Your Institute (This will simply be added to the base entry as the name of your institute)
  • Administrator password: iam@2018
  • Confirm password: must match the above
  • Database backend to use: HDB (out of the choices, this has the most functionality)
  • Do you want the database to be removed when slapd is purged? (your choice. Choose Yes to allow a completely clean removal, choose No to save your data even when the software is removed)
  • Move old database? Yes

Create the Certificate Templates

To encrypt our connections, we'll need to configure a certificate authority and use it to sign the keys for the LDAP server(s) in our infrastructure. So for our single server setup, we will need two sets of key/certificate pairs: one for the certificate authority itself and one that is associated with the LDAP service.

To create the certificates needed to represent these entities, we'll create some template files. These will contain the information that the certtool utility needs in order to create certificates with the appropriate properties.

Start by making a directory to store the template files:

sudo mkdir /etc/ssl/templates

Create the template for the certificate authority first. We'll call the file ca_server.conf. Create and open the file in your text editor:

sudo nano /etc/ssl/templates/ca_server.conf

We only need to provide a few pieces of information in order to successfully create a certificate authority. We need to specify that the certificate will be for a CA (certificate authority) by adding the ca option. We also need the cert_signing_key option to give the generated certificate the ability to sign additional certificates. We can set the cn to whatever descriptive name we'd like for our certificate authority:

cn = LDAP Server CA

Save and close the file.

Next, we can create a template for our LDAP server certificate called ldap_server.conf. Create and open the file in your text editor with sudo privileges:

sudo nano /etc/ssl/templates/ldap_server.conf

Here, we'll provide a few different pieces of information. We'll provide the name of our organization and set the tls_www_server, encryption_key, and signing_key options so that our cert has the basic functionality it needs.

The cn in this template must match the FQDN of the LDAP server. If this value does not match, the client will reject the server's certificate. We will also set the expiration date for the certificate. We'll create a 10 year certificate to avoid having to manage frequent renewals: ldapserver.conf

organization = "Name of your institution"
cn =
expiration_days = 3652

Save and close the file when you're finished.

Create CA Key and Certificate

Now that we have our templates, we can create our two key/certificate pairs. We need to create the certificate authority's set first.

Use the certtool utility to generate a private key. The /etc/ssl/private directory is protected from non-root users and is the appropriate location to place the private keys we will be generating. We can generate a private key and write it to a file called ca_server.key within this directory by typing:

sudo certtool -p --outfile /etc/ssl/private/ca_server.key

Now, we can use the private key that we just generated and the template file we created in the last section to create the certificate authority certificate. We will write this to a file in the /etc/ssl/certs directory called ca_server.pem:

sudo certtool -s --load-privkey /etc/ssl/private/ca_server.key --template /etc/ssl/templates/ca_server.conf --outfile /etc/ssl/certs/ca_server.pem

We now have the private key and certificate pair for our certificate authority. We can use this to sign the key that will be used to actually encrypt the LDAP session.

Create LDAP Service Key and Certificate

Next, we need to generate a private key for our LDAP server. We will again put the generated key in the /etc/ssl/private directory for security purposes and will call the file ldap_server.key for clarity.

We can generate the appropriate key by typing:

sudo certtool -p --sec-param high --outfile /etc/ssl/private/ldap_server.key

Once we have the private key for the LDAP server, we have everything we need to generate a certificate for the server. We will need to pull in almost all of the components we've created thus far (the CA certificate and key, the LDAP server key, and the LDAP server template).

We will put the certificate in the /etc/ssl/certs directory and name it ldap_server.pem. The command we need is:

sudo certtool -c --load-privkey /etc/ssl/private/ldap_server.key --load-ca-certificate /etc/ssl/certs/ca_server.pem --load-ca-privkey /etc/ssl/private/ca_server.key --template /etc/ssl/templates/ldap_server.conf --outfile /etc/ssl/certs/ldap_server.pem

Give OpenLDAP Access to the LDAP Server Key

We now have all of the certificates and keys we need. However, currently, our OpenLDAP process will be unable to access its own key.

A group called ssl-cert already exists as the group-owner of the /etc/ssl/private directory. We can add the user our OpenLDAP process runs under (openldap) to this group:

sudo usermod -aG ssl-cert openldap

Now, our OpenLDAP user has access to the directory. We still need to give that group ownership of the ldap_server.key file though so that we can allow read access. Give the ssl-cert group ownership over that file by typing:

sudo chown :ssl-cert /etc/ssl/private/ldap_server.key

Now, give the ssl-cert group read access to the file:

sudo chmod 640 /etc/ssl/private/ldap_server.key

Our OpenSSL process can now access the key file properly. Configure OpenLDAP to Use the Certificate and Keys

We have our files and have configured access to the components correctly. Now, we need to modify our OpenLDAP configuration to use the files we've made. We will do this by creating an LDIF file with our configuration changes and loading it into our LDAP instance.

Move to your home directory and open a file called addcerts.ldif. We will put our configuration changes in this file:

cd ~
vim addcerts.ldif

To make configuration changes, we need to target the cn=config entry of the configuration DIT. We need to specify that we are wanting to modify the attributes of the entry. Afterwards we need to add the olcTLSCACertificateFile, olcCertificateFile, and olcCertificateKeyFile attributes and set them to the correct file locations.

The end result will look like this:


Save and close the file when you are finished. Apply the changes to your OpenLDAP system using the ldapmodify command:

Start your slapd in debug mode

sudo service slapd stop
sudo slapd -h ldapi:/// -u openldap -g openldap -d 65 -F /etc/ldap/slapd.d/ -d 65

Then in another console,

sudo ldapmodify -H ldapi:// -Y EXTERNAL -f addcerts.ldif

then ctrl+c to stop the debug mode on first console and restart the service.

sudo service slapd start

Your clients can now be configured to encrypt their connections to the server over the conventional 'ldap://' port by using STARTTLS.

Setting up the Client Machines

In order to connect to the LDAP server and initiate a STARTTLS upgrade, the clients must have access to the certificate authority certificate and must request the upgrade.On the OpenLDAP Server

If you are interacting with the OpenLDAP server from the server itself, you can set up the client utilities by copying the CA certificate and adjusting the client configuration file.

First, copy the CA certificate from the /etc/ssl/certs directory to a file within the /etc/ldap directory. We will call this file ca_certs.pem. This file can be used to store all of the CA certificates that clients on this machine may wish to access. For our purposes, this will only contain a single certificate:

sudo cp /etc/ssl/certs/ca_server.pem /etc/ldap/ca_certs.pem

You should now check your connections to use STARTTLS by passing the -Z option when using the OpenLDAP utilities. You can force STARTTLS upgrade by passing it twice. Test this by typing:

ldapwhoami -H ldap:// -x -ZZ

This forces a STARTTLS connection. If this is successful, you should see:


As we haven't configure the client-side you should see an error

Now, lets adjust the system-wide configuration file for the OpenLDAP utilities. Open up the configuration file in your text editor with sudo privileges:

sudo nano /etc/ldap/ldap.conf

Adjust the value of the TLS_CACERT option to point to the file we just created:

TLS_CACERT /etc/ldap/ca_certs.pem

Save and close the file.

Test STARTTTLS again by typing:

ldapwhoami -H ldap:// -x -ZZ

Now you should see:


Load eduPerson Schema

Get the schema downloaded by

wget eduperson-201602.ldif​

Or visit to get the latest

Load it using:

sudo ldapadd -Y EXTERNAL -H ldapi:/// -f eduperson-201602.ldif

Also Lets load The SChema for Academia, SCHAC.

Get the eduPerson schema downloaded


sudo wget SCHAC.ldif

from the local repository

Or to get the latest visit and copy link to wget

Load it using:

sudo ldapadd -Y EXTERNAL -H ldapi:/// -f SCHAC.ldif

Create User Structure

Depending on your Institutes's Requirement, you may create test Groups/Users? as follows: Remember to replace XY with your number before you execute ldapadd command

dn: ou=People,dc=instXY,dc=ac,dc=lk
objectClass: organizationalUnit
objectClass: top
ou: People

dn: ou=Group,dc=instXY,dc=ac,dc=lk
objectClass: organizationalUnit
objectClass: top
ou: Group
description: All groups

dn: ou=Servers,dc=instXY,dc=ac,dc=lk
description: servers
objectClass: top
objectClass: organizationalUnit
ou: servers

dn: cn=idp,ou=servers,dc=instXY,dc=ac,dc=lk
cn: idp
description: Identity Server
ipHostNumber: 3ffe: ffff: ffff: : 9
objectClass: top
objectClass: device
objectClass: ipHost
objectClass: simpleSecurityObject
userPassword: {crypt}idpldap

Save the above as a instXY.ldif file and add it to your directory as

sudo ldapadd -H ldap:// -x -D "cn=admin,dc=instXY,dc=ac,dc=lk" -W -Z -f instXY.ldif

When Creating Users and Groups there are several ways in linking them with each other. This makes easy to search users, their associated groups as well as the groups and their associated users.

  • Option 1: Create Posix Groups, define gidNumber and link user with it. (for the tutorial purposes go through all options)


dn: cn=adm,ou=Group,dc=instXY,dc=ac,dc=lk
cn: adm
description: System Admin Staff
gidNumber: 1000
objectClass: posixGroup
objectClass: top

dn: uid=testme1,ou=people,dc=instXY,dc=ac,dc=lk
cn: Test Me
uid: testme1
uidNumber: 1001
gidNumber: 1000
givenName: Test Me1
homeDirectory: /dev/null
homePhone: none
objectClass: person
objectClass: organizationalPerson
objectClass: inetOrgPerson
objectClass: eduPerson
objectClass: posixAccount
objectClass: schacEntryMetadata
objectClass: schacLinkageIdentifiers
objectClass: extensibleObject
objectClass: top
objectClass: shadowAccount
sn: Test
mobile: +94791234567
userPassword: testme
eduPersonAffiliation: staff

Save as adm.ldif and then add to the LDAP

sudo ldapadd -H ldap:// -x -D "cn=admin,dc=instXY,dc=ac,dc=lk" -W -Z -f adm.ldif
  • Option 2: Define groupOfNames with memberOf overlay. (recommended in edugain installations)

To do this we need to create 3 .ldif files and import to the slapd.


dn: cn=module,cn=config
cn: module
objectClass: olcModuleList
olcModuleLoad: memberof
olcModulePath: /usr/lib/ldap

dn: olcOverlay={0}memberof,olcDatabase={1}hdb,cn=config
objectClass: olcConfig
objectClass: olcMemberOf
objectClass: olcOverlayConfig
objectClass: top
olcOverlay: memberof
olcMemberOfDangling: ignore
olcMemberOfRefInt: TRUE
olcMemberOfGroupOC: groupOfNames
olcMemberOfMemberAD: member
olcMemberOfMemberOfAD: memberOf


dn: cn=module{1},cn=config
add: olcmoduleload
olcmoduleload: refint


dn: olcOverlay={1}refint,olcDatabase={1}hdb,cn=config
objectClass: olcConfig
objectClass: olcOverlayConfig
objectClass: olcRefintConfig
objectClass: top
olcOverlay: {1}refint
olcRefintAttribute: memberof member manager owner

To set up the memberof module and configure it, run this command:

sudo ldapadd -Q -Y EXTERNAL -H ldapi:/// -f memberof_config.ldif

To load and configure the refint module (Referential Integrity overlay)

sudo ldapmodify -Q -Y EXTERNAL -H ldapi:/// -f refint1.ldif

sudo ldapadd -Q -Y EXTERNAL -H ldapi:/// -f refint2.ldif

Every group created before this module is enabled has to be deleted and remade in order for these changes to take effect (for an example adm group you created above). LDAP assigns a "member" attribute behind the scenes to existing users when creating a group.


dn: cn=staff,ou=Group,dc=instXY,dc=ac,dc=lk
objectClass: groupofnames
cn: staff
description: All Staff
member: uid=testme1,ou=people,dc=instXY,dc=ac,dc=lk

Make sure to add "member : user_dn" pair line for each user you want to add to this group.

Load group to the system by:

sudo ldapadd -H ldap:// -x -D "cn=admin,dc=instXY,dc=ac,dc=lk" -W -Z -f addgroup.ldif

You may test your users by:

ldapsearch -x -LLL -H ldap:/// -b ou=people,dc=instXY,dc=ac,dc=lk dn memberof gidNumber

Note that a user can have only one gidNumber but can have multiple memberof values.

More details on federated attributes

More on SCHAC schema

Last modified 3 years ago Last modified on Jun 6, 2019, 12:58:59 PM

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