What is Kerberos?

Kerberos is a network authentication protocol developed at MIT in the 1980s to enhance secure communication over untrusted networks. It ensures secure user and service authentication without transmitting passwords directly, leveraging symmetric key cryptography and a trusted third party known as the Key Distribution Center (KDC).

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1. Initial Authentication: The client requests an authentication ticket (TGT) from the KDC's Authentication Server (AS).
2. Ticket Granting: The KDC validates credentials and returns an encrypted TGT and session key.
3. Service Access: The client uses the TGT to request a service ticket from the Ticket Granting Server (TGS).
4. Service Authentication: The service ticket is presented to the server, granting access upon verification.

• Enhanced Security: Passwords are never transmitted over the network, reducing interception risks.
• Centralized Authentication: Provides a single point for managing logins and enforcing security policies.
• Scalability: Designed for large, distributed networks and integration with various operating systems.

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Kerberos is widely used in:

• Microsoft Windows Active Directory
• UNIX and Linux systems
• Single Sign-On (SSO) implementations
• Network service security, including SSH, POP, and SMTP protocols.