Kerberos Authentication: An Comprehensive 6 Step Guide

Ajay Ohri


When using any online service, you can be vulnerable to many threats that can come online when you browse the internet. One such is the retrieving of your user ID. For instance, when you log in to your account on some website over an unknown network, your information might be open to attackers. Your user id, including your password, can be tracked by the attackers even if you have logged out of the website. This can be a threat to privacy. Kerberos authentication is one of the most commonly used precautions used by many people to protect their login credentials. 

In this article let us look at:

  1. What Is Kerberos?
  2. Principle Of Kerberos Authentication System
  3. How Kerberos Work?
  4. Pros And Cons Of Kerberos
  5. Uses Of Kerberos
  6. Examples of Kerberos Authentication

1. What Is Kerberos?

The term Kerberos authentication has been derived from a mythological creature. Kerberos was a three-headed dog with the serpent’s tail, a mane of snakes, and the lion’s claws. He was summoned to guard the underworld’s gates to protect and prevent the dead’s shades from escaping. At various, it has been mentioned that the Kerberos has around 50 heads, and some believe that to be with the snake’s mane.

In the world of the internet, the Kerberos meaning is different. The user’s authentic connection to the server and the server to the user is the Kerberos Authentication Process. Kerberos authentication protocol was developed by the Massachusetts Institute of technology in the late 1980s to protect its project. They work behind the idea of authenticating users to avoid sending passwords to the internet. Many insecure networks can easily adapt to the authentication protocol. This is because this is strong cryptography and is developed on the client-server model.

2. Principle Of Kerberos Authentication System

The main principle around which the Kerberos protocol works is the users’ authentication not to share the password. The Kerberos architecture consists of three main components: the authentication server, database, and ticket-granting server.

The authentication server helps with the initial stage of the authentication and ticket. The database in the architecture is then used to verify the access rights of users in the database. The TGS or the ticket-granting server issues the ticket for the server.

Other components of the system are client, server, key distribution center, ticket-granting ticket.

3. How Kerberos Work?

Given below are the Kerberos authentication steps, which very well explains the Kerberos meaning and its working.

  1. The very first step for Kerberos security is the initial client authentication request. In this step, the user will ask for a ticket-granting ticket from the authentication server. The client ID will also be included in the request that is sent.
  2. Next, the credentials of the client are verified by the key distribution center. At first, the authentication server checks whether the client and the ticket-granting server are available or not. If both are available, then the authentications server will generate a client/user secret key. This will employ hash as the user’s password. Then the ticket-granting server secret key is computed by the authentication server. It also creates a session key, which is encrypted by the client/user secret key. Then a ticket-granting ticket is generated by the authentications server, which also contains the client ID, timestamp, session key, lifetime, and client network address. Then, the ticket is encrypted by the Ticker granting a secret server key.
  3. The client then decrypts the message. The client uses the user/client secret key to decrypt the message. It also extracts the secret key and TGT and also generates the authenticator to validate the TGS of the client.
  4. Then the client request access using TGT.
  5. The key distribution center then creates a ticket for the file server. The ticket-granting server uses the secret key for decrypting the ticket-granting ticket that is received from the client. Then the secret key is extracted. Then the authenticator decrypts the ticket-granting ticket and matches it with the client ID and client network address. Also, it uses the timestamp to make sure the ticket is not expired. The key distribution center then creates a service ticket.
  6. The client then uses the file ticket to authenticate.
  7. In the final step, the target server receives authentication as well as the decryption.

This was the whole working of the Kerberos.

4. Pros And Cons Of Kerberos

Though the Kerberos protocol is secure to protect users’ passwords, there are some pros and cons.


  • When running on a Kerberos network, you will not have to worry about your passwords or user ID not getting shared by anyone. This is because the keys on the Kerberos system are sent in encrypted form.
  • The authentication is mutual for both the server and the users. So the data shared between the user and the server is end-to-end encrypted and can only be accessed by the server and the user.
  • The authentication does not expire and can be reused.
  • The Kerberos authentication follows the Internet Standards.
  • The security system is less vulnerable. It is so because various industries and MNCs, so any vulnerability in the protocols are worked upon.


  • If the Key distribution center gets accessed by a user who is not authorized, the whole system will have to compromise.
  • Only systems that are Kerberos aware applications can run Kerberos.

5. Uses Of Kerberos

One can find Kerberos authentication system everywhere around the digital world. These are implemented everywhere where users send ID details, including the password, to the servers. This helps the details sent by the users to the servers so that no one hacks it. This helps secure the users’ details and follows end-to-end encryption to ensure the user’s data is safe. These are implemented on systems that require reliable auditing and authentication features to help protect users’ privacy.

6. Examples of Kerberos Authentication

There are various examples of the use of Kerberos Authentication in the online world. There are various places where Kerberos security is used, such as Active Directory, Posix Authentication, Samba, and NFS. The Kerberos authentication system also works as an alternative authentication system to SSH, SMTP, and POP. Windows 2000 and all the Windows after that used Kerberos as the default authentication method. Various Unix operating systems also used the Kerberos authentication system for the added security.


This is complete Kerberos explained. Kerberos is adapted by various businesses online and various brands to ensure that the users’ connection to the server is secure. This ensures that the user’s connection to the server is encrypted, and the password and User ID shared by the user is encrypted and can only be read by the server. This ensures that the system is not vulnerable to any attacks. Reading this article you will know all about using Kerberos security even it’s working and uses.

So, have you made up your mind to make a career in Cyber Security? Visit our Master Certificate in Cyber Security (Red Team) for further help. It is the first program in offensive technologies in India and allows learners to practice in a real-time simulated ecosystem, that will give you an edge in this competitive world.

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