Question

Cybersecurity

Explain what is LDAP, what does it do, and what is the best way for a client to connect to an LDAP server. Write a whole paragraph to explain your answer.

Answer 1

Answer:-

what is LDAP:-

Lightweight Directory Access Protocol (LDAP) is a client/server protocol used to access and manage directory information. It reads and edits directories over IP networks and runs directly over TCP/IP using simple string formats for data transfer. It was originally developed as a front end to X.500 Directory Access Protocol.

what does it do:-

The use model is similar like how people use library cards or phonebooks. When you have a task that requires “write/update once, read/query many times”, you might consider using LDAP. LDAP is designed to provide extremely fast read/query performance for a large scale of dataset. Typically you want to store only a small piece of information for each entry. The add/delete/update performance is relatively slower compared with read/query because the assumption is that you don’t do “update” that often.

Imagine you have a website that has a million registered users with thousands of page requests per second. Without LDAP, every time users click a page, even for static page viewing, you will probably need to interact with your database to validate the user ID and its digital signature for this login session. Obviously, the query to your database for user-validation will become your bottleneck. By using LDAP, you can easily offload the user validation and gain significant performance improvement. Essentially, in this example, LDAP is another optimization layer outside your database to enhance performance, not replacing any database functions.

LDAP is not just for user validation, any task that has the following properties might be a good use case for LDAP:

1. You need to locate ONE piece of data many times and you want it fast

2. You don’t care about the logic and relations between different data

3. You don’t update, add, or delete the data very often

4. The size of each data entry is small

5. You don’t mind having all these small pieces of data at a centralized place

what is the best way for a client to connect to an LDAP:-

LDAP (short for Lightweight Directory Access Protocol) is an industry standard, widely used set of protocols for accessing directory services.

A directory service in simple terms is a centralized, network-based database optimized for read access. It stores and provides access to information that must either be shared between applications or is highly distributed.

Directory services play an important role in developing intranet and Internet applications by helping you share information about users, systems, networks, applications, and services throughout the network.

A typical use case for LDAP is to offer a centralized storage of usernames and passwords. This allows various applications (or services) to connect to the LDAP server to validate users.

After setting up a working LDAP server, you will need to install libraries on the client for connecting to it. In this article, we will show how to configure an LDAP client to connect to an external authentication source.

I hope you already having a working LDAP server environment, if not setup Up LDAP Server for LDAP-based Authentication.

How to Install and Configure LDAP Client in Ubuntu and CentOS

On the client systems, you will needs to install a few necessary packages to make authentication mechanism function correctly with an LDAP server.

Configure LDAP Client in Ubuntu 16.04 and 18.04

First start by installing the necessary packages by running the following command.

$ sudo apt update && sudo apt install libnss-ldap libpam-ldap ldap-utils nscd

During the installation, you will be prompted for details of your LDAP server (provide the values according to your environment). Note that the ldap-auth-config package which is auto-installed does the most of the configurations based on the inputs you enter.

Enter LDAP Server URI

Next, enter the name of the LDAP search base, you can use the components of their domain names for this purpose as shown in the screenshot.

Enter LDAP Search Base

Also choose the LDAP version to use and click Ok.

Select LDAP Version

Now configure the option to allow you to make password utilities that use pam to behave like you would be changing local passwords and click Yes to continue..

Make Local Root Database Admin

Next, disable login requirement to the LDAP database using the next option.

Disable Login to LDAP Database

Also define LDAP account for root and click Ok.

Define LDAP Account for Root

Next, enter the password to use when ldap-auth-config tries to login to the LDAP directory using the LDAP account for root.

Enter LDAP Root Password

The results of the dialog will be stored in the file /etc/ldap.conf. If you want to make any alterations, open and edit this file using your favorite command line editor.

Next, configure the LDAP profile for NSS by running.

$ sudo auth-client-config -t nss -p lac_ldap

Then configure the system to use LDAP for authentication by updating PAM configurations. From the menu, choose LDAP and any other authentication mechanisms you need. You should now be able to log in using LDAP-based credentials.

$ sudo pam-auth-update

Configure PAM Authentication Mechanism

In case you want the home directory of the user to be created automatically, then you need to perform one more configuration in the common-session PAM file.

$ sudo vim /etc/pam.d/common-session

Add this line in it.

session required pam_mkhomedir.so skel=/etc/skel umask=077

Save the changes and close the file. Then restart the NCSD (Name Service Cache Daemon) service with the following command.

$ sudo systemctl restart nscd
$ sudo systemctl enable nscd

Note: If you are using replication, LDAP clients will need to refer to multiple servers specified in /etc/ldap.conf. You can specify all the servers in this form:

uri ldap://ldap1.example.com  ldap://ldap2.example.com

This implies that the request will time out and if the Provider (ldap1.example.com) becomes unresponsive, the Consumer (ldap2.example.com) will attempt to be reached to process it.

To check the LDAP entries for a particular user from the server, run the getent command, for example.

$ getent passwd tecmint

If the above command displays details of the specified user from the /etc/passwd file, your client machine is now configured to authenticate with the LDAP server, you should be able to log in using LDAP-based credentials.

Configure LDAP Client in CentOS 7

To install the necessary packages, run the following command. Note that in this section, if you are operating the system as a non-root administrative user, use the sudo command to run all commands.

# yum update && yum install openldap openldap-clients nss-pam-ldapd

Next, enable the client system to authenticate using LDAP. You can use the authconfig utility, which is an interface for configuring system authentication resources.

Run the following command and replace example.com with your domain and dc=example,dc=com with your LDAP domain controller.

# authconfig --enableldap --enableldapauth --ldapserver=ldap.example.com --ldapbasedn="dc=example,dc=com" --enablemkhomedir --update

In the above command, the --enablemkhomedir option creates a local user home directory at the first connection if none exists.

Next, test if the LDAP entries for a particular user from the server, for example user tecmint.

$ getent passwd tecmint

The above command should display details of the specified user from the /etc/passwd file, which implies that the client machine is now configured to authenticate with the LDAP server.

Important: If SELinux is enabled on your system, you need to add a rule to allow creating home directories automatically by mkhomedir.