openldap

Try to follow the instructions very precisely because LDAP syntax is sometimes cumbersome (case sensitive, space, etc) and prone to errors (dn/dc/cn).
Let’s assume that we use the example.com domain and the instructor.example.com hostname.

Install the following packages:

# yum install -y openldap openldap-clients openldap-servers migrationtools

Generate a LDAP password from a secret key (here redhat):

# slappasswd -s redhat -n > /etc/openldap/passwd

Generate a X509 certificate valid for 365 days:

# openssl req -new -x509 -nodes -out /etc/openldap/certs/cert.pem -keyout /etc/openldap/certs/priv.pem -days 365Generating a 2048 bit RSA private key
.....+++
..............+++
writing new private key to '/etc/openldap/certs/priv.pem'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:
State or Province Name (full name) []:
Locality Name (eg, city) [Default City]:
Organization Name (eg, company) [Default Company Ltd]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:instructor.example.comEmail Address []:

Secure the content of the /etc/openldap/certs directory:

# cd /etc/openldap/certs# chown ldap:ldap *# chmod 600 priv.pem

Prepare the LDAP database:

# cp /usr/share/openldap-servers/DB_CONFIG.example /var/lib/ldap/DB_CONFIG

Generate database files (don’t worry about error messages!):

# slaptest53d61aab hdb_db_open: database "dc=my-domain,dc=com": db_open(/var/lib/ldap/id2entry.bdb) failed: No such file or directory (2).
53d61aab backend_startup_one (type=hdb, suffix="dc=my-domain,dc=com"): bi_db_open failed! (2)
slap_startup failed (test would succeed using the -u switch)

Change LDAP database ownership:

# chown ldap:ldap /var/lib/ldap/*

Activate the slapd service at boot:

# systemctl enable slapd

Start the slapd service:

# systemctl start slapd

Check the LDAP activity:

# netstat -lt | grep ldaptcp        0      0 0.0.0.0:ldap            0.0.0.0:*               LISTEN     
tcp6       0      0 [::]:ldap               [::]:*                  LISTEN

To start the configuration of the LDAP server, add the cosine & nis LDAP schemas:

# cd /etc/openldap/schema# ldapadd -Y EXTERNAL -H ldapi:/// -D "cn=config" -f cosine.ldifSASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
adding new entry "cn=cosine,cn=schema,cn=config"
# ldapadd -Y EXTERNAL -H ldapi:/// -D "cn=config" -f nis.ldifSASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
adding new entry "cn=nis,cn=schema,cn=config"

Then, create the /etc/openldap/changes.ldif file and paste the following lines (replace password with the previously created password):

dn: olcDatabase={2}hdb,cn=config
changetype: modify
replace: olcSuffix
olcSuffix: dc=example,dc=com

dn: olcDatabase={2}hdb,cn=config
changetype: modify
replace: olcRootDN
olcRootDN: cn=Manager,dc=example,dc=com

dn: olcDatabase={2}hdb,cn=config
changetype: modify
replace: olcRootPW
olcRootPW: passwd # previously generated password

dn: cn=config
changetype: modify
replace: olcTLSCertificateFile
olcTLSCertificateFile: /etc/openldap/certs/cert.pem

dn: cn=config
changetype: modify
replace: olcTLSCertificateKeyFile
olcTLSCertificateKeyFile: /etc/openldap/certs/priv.pem

dn: cn=config
changetype: modify
replace: olcLogLevel
olcLogLevel: -1

dn: olcDatabase={1}monitor,cn=config
changetype: modify
replace: olcAccess
olcAccess: {0}to * by dn.base="gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" read by dn.base="cn=Manager,dc=example,dc=com" read by * none

Send the new configuration to the slapd server:

# ldapmodify -Y EXTERNAL -H ldapi:/// -f /etc/openldap/changes.ldifSASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0
modifying entry "olcDatabase={2}hdb,cn=config"
modifying entry "olcDatabase={2}hdb,cn=config"
modifying entry "olcDatabase={2}hdb,cn=config"
modifying entry "cn=config"
modifying entry "cn=config"
modifying entry "cn=config"
modifying entry "olcDatabase={1}monitor,cn=config"

Create the /etc/openldap/base.ldif file and paste the following lines:

dn: dc=example,dc=com
dc: example
objectClass: top
objectClass: domain

dn: ou=People,dc=example,dc=com
ou: People
objectClass: top
objectClass: organizationalUnit

dn: ou=Group,dc=example,dc=com
ou: Group
objectClass: top
objectClass: organizationalUnit

Build the structure of the directory service:

# ldapadd -x -w redhat -D cn=Manager,dc=example,dc=com -f base.ldifadding new entry "dc=example,dc=com"
adding new entry "ou=People,dc=example,dc=com"
adding new entry "ou=Group,dc=example,dc=com"

Create two users for testing:

# mkdir /home/guests# useradd -d /home/guests/ldapuser01 ldapuser01# passwd ldapuser01Changing password for user ldapuser01.
New password:user01ldapRetype new password:user01ldappasswd: all authentication tokens updated successfully.
# useradd -d /home/guests/ldapuser02 ldapuser02# passwd ldapuser02Changing password for user ldapuser02.
New password:user02ldapRetype new password:user02ldappasswd: all authentication tokens updated successfully.

Go to the directory for the migration of the user accounts:

# cd /usr/share/migrationtools

Edit the migrate_common.ph file and replace in the following lines:

$DEFAULT_MAIL_DOMAIN = "example.com";
$DEFAULT_BASE = "dc=example,dc=com";

Create the current users in the directory service:

# grep ":10[0-9][0-9]" /etc/passwd > passwd# ./migrate_passwd.pl passwd users.ldif# ldapadd -x -w redhat -D cn=Manager,dc=example,dc=com -f users.ldifadding new entry "uid=ldapuser01,ou=People,dc=example,dc=com"
adding new entry "uid=ldapuser02,ou=People,dc=example,dc=com"
# grep ":10[0-9][0-9]" /etc/group > group# ./migrate_group.pl group groups.ldif# ldapadd -x -w redhat -D cn=Manager,dc=example,dc=com -f groups.ldifadding new entry "cn=ldapuser01,ou=Group,dc=example,dc=com"
adding new entry "cn=ldapuser02,ou=Group,dc=example,dc=com"

Test the configuration with the user called ldapuser01:

# ldapsearch -x cn=ldapuser01 -b dc=example,dc=com

Add a new service to the firewall (ldap: port tcp 389):

# firewall-cmd --permanent --add-service=ldap

Reload the firewall configuration:

# firewall-cmd --reload

Edit the /etc/rsyslog.conf file and add the following line:

local4.* /var/log/ldap.log

Restart the rsyslog service:http://www.certdepot.net

# systemctl restart rsyslog