Kerberos V5 System Administrator's Guide (2024)

FAQs

How does the Kerberos version 5 authentication protocol work? ›

Kerberos tickets represent the client's network credentials. Like NTLM, the Kerberos protocol uses the domain name, user name, and password to represent the client's identity. The initial Kerberos ticket obtained from the KDC when the user logs on is based on an encrypted hash of the user's password.

This administrative domain is the Kerberos realm . Each Kerberos realm will have at least one Kerberos server, where the master Kerberos database for that site or administrative domain is stored.

Encryption: Kerberos V5 uses a more secure encryption algorithm than Kerberos V4, which makes it less vulnerable to attacks. Ticket-granting service (TGS): Kerberos V5 uses multiple TGS servers to handle requests for different network services.

A Kerberos is a system or router that provides a gateway between users and the internet. Therefore, it helps prevent cyber attackers from entering a private network.

Despite being created 40+ years ago, Kerberos has still plenty of advantages network administrators can benefit from: Strong security. The cryptography Kerberos uses provides strong authentication mechanisms and ensures that only trusted users can access the network.

The primary weakness of Kerberos is that the KDC stores the keys of all principals (clients and servers). A compromise of the KDC (physical or electronic) can lead to the compromise of every key in the Kerberos realm. The KDC and TGS are also single points of failure. If they go down, no new credentials can be issued.

Kerberos is used to authenticate entities requesting access to network resources, especially in large networks to support SSO. The protocol is used by default in many widely used networking systems. Some systems in which Kerberos support is incorporated or available include the following: Amazon Web Services.

These requirements include: Secure Authentication: Kerberos uses a trusted Key Distribution Center (KDC) which holds the keys for both clients and services for secure authentication. Timestamps: Kerberos protocol includes timestamps in its authentication process to prevent replay attacks.

The default ports used by Kerberos are port 88 for the KDC¹ and port 749 for the admin server.

How does Kerberos authentication work step by step? ›

Kerberos Authentication Steps

The client's request includes the user's User Principal Name (UPN) and a timestamp. It is encrypted using the user's password hash. The KDC uses the UPN to look up the client in its database and uses the user's password hash to attempt to decrypt the message.

The default username and password of the Kerberos Vault app is: username: root. password: kerberos.

V5 is a family of telephone network protocols defined by ETSI which allow communications between the telephone exchange, also known in the specifications as the local exchange (LE), and the local loop.

During an authentication process, like when a user logs in to a digital service, they must prove their identity to the verifier. Authentication protocols dictate the type of information needed for the authenticating service to verify the user and how it's delivered.

Kerberos protocol messages are protected against eavesdropping and replay attacks. Kerberos builds on symmetric-key cryptography and requires a trusted third party, and optionally may use public-key cryptography during certain phases of authentication. Kerberos uses UDP port 88 by default.