LDAP server installation and configuration step by step – RHEL7

openLDAP server installation and configuration step by step – RHEL7

BY D.RAJESH KANNAN · PUBLISHED JUNE 10, 2016 

openLDAP directory service is based on a client-server model. LDAP transferred “Lightweight directory access protocol”   is a directory service protocol that runs on a layer above the TCP/IP stack. It provides a mechanism used to connect to, search, and modify Internet directories. The LDAP directory service is based on a client-server model.

openLDAP is used to facilitate centralized user management. It eliminates users creation on each and every server, instead of creating users and there profile in all the servers we can create them in LDAP server and access from all the LDAP client machines.

Few advantages of openLDAP

• Global naming model ensures unique entries
• Allows for multiple independent directories
• Extensible to meet future/local requirements
• Runs directly over TCP/IP and SSL
• Has broad industry support
• Based on existing deployed technologies
• Schema definitions
• Schema publication
• Security features
• Extended operation framwork
• Synamic and pages search extentions

This tutorial will explain how to install and configure openLDAP server and it’s configuration with user home directory auto mount using NFS autofs

Please observe step by step and modify your requirements accordingly

Let’s start the configuration

Requirements – RHEL7/Centos 7 with minimal installation OR GUI installation is enough

Tested Centos7, RHEL7, RHEL7.1 and RHEL7.2 versions

Server Profile :-

Packages : openldap, migrationtools

Port Number: 389, 636

Step 1:  Installing LDAP packages using yum

[root@ark-ldapserver ~]# yum -y install *openldap* migrationtools

generating LDAP admin password

[root@ark-ldapserver ~]# slappasswd
New password: 
Re-enter new password: 
{SSHA}KczPx+72Gz5W4Tv58EgT8beoPsuxkekO

as shown in above slappasswd command will generate an password with encryption, please copy above encrypted password and keep it safe this password we are going to use in further configuration

add the generated password to below file and change olcSuffix olcRootDN olcRootPW  and add key file location as shown in below (bold ones have to modify)

[root@ark-ldapserver ~]# cd /etc/openldap/slapd.d/cn\=config/
[root@ark-ldapserver cn=config]# vi olcDatabase\=\{2\}hdb.ldif 
# AUTO-GENERATED FILE - DO NOT EDIT!! Use ldapmodify.
# CRC32 5514a54b
dn: olcDatabase={2}hdb
objectClass: olcDatabaseConfig
objectClass: olcHdbConfig
olcDatabase: {2}hdb
olcDbDirectory: /var/lib/ldap
olcSuffix: dc=arkit,dc=co.in
olcRootDN: cn=Manager,dc=arkit,dc=co.in
olcDbIndex: objectClass eq,pres
olcDbIndex: ou,cn,mail,surname,givenname eq,pres,sub
structuralObjectClass: olcHdbConfig
entryUUID: 7ffd78be-8216-1035-9daa-e3230d8ea492
creatorsName: cn=config
createTimestamp: 20160319120438Z
entryCSN: 20160319120438.887404Z#000000#000#000000
modifiersName: cn=config
modifyTimestamp: 20160319120438Z
olcRootPW: {SSHA}KczPx+72Gz5W4Tv58EgT8beoPsuxkekO
olcTLSCertificateFile: /etc/pki/tls/certs/arkitldap.pem
olcTLSCertificateKeyFile: /etc/pki/tls/certs/arkitkey.pem

Now edit the file monitor.ldif and add modify dc=my-domain,dc=com to your domain as shown in below

[root@ark-ldapserver cn=config]# vi olcDatabase\=\{1\}monitor.ldif 
# AUTO-GENERATED FILE - DO NOT EDIT!! Use ldapmodify.
# CRC32 3eb2863a
dn: olcDatabase={1}monitor
objectClass: olcDatabaseConfig
olcDatabase: {1}monitor
olcAccess: {0}to * by dn.base="gidNumber=0+uidNumber=0,cn=peercred,cn=external
,cn=auth" read by dn.base="cn=Manager,dc=arkit,dc=co.in" read by * none
structuralObjectClass: olcDatabaseConfig
entryUUID: 7ffd68a6-8216-1035-9da9-e3230d8ea492
creatorsName: cn=config
createTimestamp: 20160319120438Z
entryCSN: 20160319120438.886990Z#000000#000#000000
modifiersName: cn=config
modifyTimestamp: 20160319120438Z

test your LDAP configuration using below command, you may see few checksum errors no problem don’t bother

[root@ark-ldapserver cn=config]# slaptest -u
56ed4143 ldif_read_file: checksum error on "/etc/openldap/slapd.d/cn=config/olcDatabase={1}monitor.ldif"
56ed4143 ldif_read_file: checksum error on "/etc/openldap/slapd.d/cn=config/olcDatabase={2}hdb.ldif"
config file testing succeeded

Step 2: Start LDAP server slapd.service

use below command to start and enable the service to start after the server reboot

[root@ark-ldapserver cn=config]# systemctl enable slapd.service
ln -s '/usr/lib/systemd/system/slapd.service' '/etc/systemd/system/multi-user.target.wants/slapd.service'
[root@ark-ldapserver cn=config]# systemctl start slapd.service
[root@ark-ldapserver cn=config]# netstat -lt |grep ldap
tcp 0 0 0.0.0.0:ldap 0.0.0.0:* LISTEN
tcp6 0 0 [::]:ldap [::]:* LISTEN

Step 3: Generate certificate

generating x509 certificate for 365 days

[root@ark-ldapserver cn=config]# openssl req -new -x509 -nodes -out /etc/pki/tls/certs/arkitldap.pem -keyout /etc/pki/tls/certs/arkitkey.pem -days 365
Generating a 2048 bit RSA private key
..................+++
.................................................................................................................................+++
writing new private key to '/etc/pki/tls/certs/arkitkey.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]:IN
State or Province Name (full name) []:Telangana
Locality Name (eg, city) [Default City]:Hyderabad
Organization Name (eg, company) [Default Company Ltd]:arkit
Organizational Unit Name (eg, section) []:IT
Common Name (eg, your name or your server's hostname) []:ark-ldapserver
Email Address []:
[root@ark-ldapserver cn=config]#

as mentioned above you can give the details are else just hit enter in all the fields. verify your certificate files by listing directory, key file names should match exactly with Step 1 configuration

[root@ark-ldapserver cn=config]# ll /etc/pki/tls/certs/
total 20
-rw-r--r--. 1 root root 1704 Mar 19 17:42 arkitkey.pem
-rw-r--r--. 1 root root 1330 Mar 19 17:42 arkitldap.pem

Step 4: Change migration config

Go to directory path as mentioned below and edit the file migrate_common.ph file add few entries as shown in below screen

[root@ark-ldapserver cn=config]# cd /usr/share/migrationtools/
[root@ark-ldapserver migrationtools]# vi migrete_common.ph 
$DEFAULT_MAIL_DOMAIN = "arkit.co.in";
$DEFAULT_BASE = "dc=arkit,dc=co.in";
$EXTENDED_SCHEMA = 1;

Step 5: Creating openLDAP database file

Now we just create an openLDAP database with file extension as .ldif

[root@ark-ldapserver migrationtools]# touch /root/base.ldif
[root@ark-ldapserver migrationtools]# cat /root/base.ldif
dn: dc=arkit,dc=co.in
objectClass: top
objectClass: dcObject
objectclass: organization
o: arkit co.in
dc: arkit
dn: cn=Manager,dc=arkit,dc=co.in
objectClass: organizationalRole
cn: Manager
description: Directory Manager
dn: ou=People,dc=arkit,dc=co.in
objectClass: organizationalUnit
ou: People
dn: ou=Group,dc=arkit,dc=co.in
objectClass: organizationalUnit
ou: Group

Step 6: Creating users and groups

Create normal Linux users along with there primary groups

[root@ark-ldapserver migrationtools]# useradd ldapuser1
[root@ark-ldapserver migrationtools]# useradd ldapuser2
[root@ark-ldapserver migrationtools]# useradd ldapuser3
[root@ark-ldapserver migrationtools]# passwd ldapuser1
Changing password for user ldapuser1.
New password: 
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: 
passwd: all authentication tokens updated successfully.
[root@ark-ldapserver migrationtools]# passwd ldapuser2
Changing password for user ldapuser2.
New password: 
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: 
passwd: all authentication tokens updated successfully.
[root@ark-ldapserver migrationtools]# passwd ldapuser3
Changing password for user ldapuser3.
New password: 
BAD PASSWORD: The password is shorter than 8 characters
Retype new password: 
passwd: all authentication tokens updated successfully.

now gather all the users and groups information to separate files

[root@ark-ldapserver migrationtools]# cat /etc/pass wd |grep ldapuser > /root/password
[root@ark-ldapserver migrationtools]# cat /root/password
ldapuser1:x:1001:1001::/home/ldapuser1:/bin/bash
ldapuser2:x:1002:1002::/home/ldapuser2:/bin/bash
ldapuser3:x:1003:1003::/home/ldapuser3:/bin/bash
[root@ark-ldapserver migrationtools]# cat /etc/group |grep ldapuser > /root/groups

after that migrate your local users as openLDAP users

[root@ark-ldapserver migrationtools]# ./migrate_passwd.pl /root/password /root/users.ldif
[root@ark-ldapserver migrationtools]# ./migrate_group.pl /root/groups /root/groups.ldif
[root@ark-ldapserver migrationtools]# ldapadd -x -W -D "cn=Manager,dc=arkit,dc=co.in" -f /root/base.ldif 
Enter LDAP Password: 
adding new entry "dc=arkit,dc=co.in"
adding new entry "cn=Manager,dc=arkit,dc=co.in"
adding new entry "ou=People,dc=arkit,dc=co.in"
adding new entry "ou=Group,dc=arkit,dc=co.in"
[root@ark-ldapserver migrationtools]# ldapadd -x -W -D "cn=Manager,dc=arkit,dc=co.in" -f /root/users.ldif 
Enter LDAP Password: 
adding new entry "uid=ldapuser1,ou=People,dc=arkit,dc=co.in"
adding new entry "uid=ldapuser2,ou=People,dc=arkit,dc=co.in"
adding new entry "uid=ldapuser3,ou=People,dc=arkit,dc=co.in"
[root@ark-ldapserver migrationtools]# ldapadd -x -W -D "cn=Manager,dc=arkit,dc=co.in" -f /root/groups.ldif 
Enter LDAP Password: 
adding new entry "cn=ldapuser1,ou=Group,dc=arkit,dc=co.in"
adding new entry "cn=ldapuser2,ou=Group,dc=arkit,dc=co.in"
adding new entry "cn=ldapuser3,ou=Group,dc=arkit,dc=co.in"

Verify the users using below command

[root@ark-ldapserver migrationtools]# ldapsearch -x cn=ldapuser3 -b dc=arkit,dc=co.in

Step 7: Allow firewall ports

we have to allow ldap and ldaps port numbers

[root@ark-ldapserver migrationtools]# firewall-cmd --permanent --add-service=ldap
success
[root@ark-ldapserver migrationtools]# firewall-cmd --permanent --add-service=ldaps
success
[root@ark-ldapserver migrationtools]# firewall-cmd --reload 
success

Thats about openLDAP server configuration now we will see how to export LDAP users home directories

Step 8: Install NFS util packages

[root@ark-ldapserver migrationtools]# yum -y install rpcbind nfs-utils

Enable and start the NFS service

[root@ark-ldapserver migrationtools]# systemctl enable nfs-server.service 
ln -s '/usr/lib/systemd/system/nfs-server.service' '/etc/systemd/system/multi-user.target.wants/nfs-server.service'
[root@ark-ldapserver migrationtools]# systemctl start nfs-server.service
[root@ark-ldapserver migrationtools]# systemctl enable rpcbind
[root@ark-ldapserver migrationtools]# systemctl start rpcbind

configure NFS export

[root@ark-ldapserver migrationtools]# vi /etc/exports
/home *(rw,sync)
[root@ark-ldapserver migrationtools]# systemctl restart nfs-server.service 

Enable NFS and it’s supported Firewall ports

[root@ark-ldapserver migrationtools]# firewall-cmd --permanent --add-service=nfs
success
[root@ark-ldapserver migrationtools]# firewall-cmd --permanent --add-service=rpc-bind
success
[root@ark-ldapserver migrationtools]# firewall-cmd --permanent --add-service=mountd
success
[root@ark-ldapserver migrationtools]# firewall-cmd --reload
success
[root@ark-ldapserver migrationtools]# showmount -e localhost
Export list for localhost:
/home *.arkit.co.in
[root@ark-ldapserver ~]# chmod 777 /home
[root@ark-ldapserver ~]# systemctl restart slapd.service
[root@ark-ldapserver ~]# systemctl status slapd.service

That’s it about openLDAP server configuration

Manually Repair Windows 7 Boot Loader Problems

Boot From the Windows Install Disc

The first thing you’ll need to do is boot off the install disc, and then click through until you see the “Repair your computer” link in the lower left-hand corner.

You’ll need to choose the correct installation of Windows and then click the Next button.

And then you’ll get to the System Recovery Options screen, where you can get to the Command Prompt.

Repairing the Master Boot Record

If you want to restore the master boot record, you can simply type in the following command:

bootrec /fixmbr

You can also write a new boot sector onto the system partition with this command (which is often more useful):

bootrec /fixboot

And of course, if you just use bootrec /? you’ll be able to see all the options.

This is the same way that we fixed the “BOOTMGR is missing” error when trying to boot up Windows 7 or Vista.

Replacing the Windows XP Bootloader with Windows 7

If you’ve managed to install XP on the same PC that you already had Windows 7 on, you’ll noticed that you can’t boot into Windows 7 anymore. You can use this command to fix that and restore the Windows 7 bootloader:

bootsect /nt60 all

Depending on the partition that you’ve installed, you might need to substitute the drive letter instead of “all”.

Note: if you want to restore Windows XP back to the menu, you can open up a command prompt in Windows 7 and run this command:

bcdedit /create {ntldr} -d “Windows XP”

Using the Automated Startup Repair

Of course, all this command-line stuff is probably not necessary in most cases. You can usually just use the Startup Repair option from the Recovery menu…

It’ll check for problems and probably fix them. If not, then you can always use the command prompt.

How to Reset Your Forgotten Domain Admin Password on Server 2008 R2

How to Reset Your Forgotten Domain Admin Password on Server 2008 R2

Forgetting your password is always a pain, but luckily there’s an easy way to reset your Domain Administrator password. All you need is a copy of the Windows Server 2008 R2 installation disk and one simple command line trick.

Replacing Utilman.exe

Boot off the Windows disk and select the “Repair your computer” option from the lower left-hand corner.

Follow through until you get to the option to open the Command Prompt, which you’ll want to select.

First you’ll want to type in the following command to backup the utilman.exe file:

MOVE C:\Windows\System32\Utilman.exe C:\Windows\System32\Utilman.exe.bak

Now you will need to copy cmd.exe and rename it Utilman.exe:

COPY C:\Windows\System32\cmd.exe C:\Windows\System32\Utilman.exe

Now you can go ahead and reboot your machine. When its done booting up again and you are at the Logon screen click on the Ease of access icon.

I bet you weren’t expecting that open a command prompt  To change the password type:

net user administrator *

Once you press enter you will asked to set a new password and then confirm it, when entering your new password don’t worry if you can’t see them as you type, they are invisible, they are however being remembered.

Once you’re logged in again don’t forget to delete Utilman.exe and then rename Utilman.exe.bak back to plain old Utilman.exe.