What is the main advantage of using Kerberos over NTLM regarding network security?

The main advantage of using Kerberos over NTLM in terms of network security is that Kerberos can effectively prevent replay attacks. Replay attacks occur when a malicious actor intercepts a valid data transmission and later retransmits it to gain unauthorized access or perform actions as if they were the legitimate sender.

Kerberos employs a system of time-stamped tickets and session keys to create a secure authentication process. Each ticket is issued with a timestamp and is valid for a limited period, which helps prevent attackers from reusing a ticket after it has expired. Additionally, because each authentication session is unique and utilizes session keys that are not reused for other sessions, it becomes extremely difficult for an attacker to successfully replay a captured authentication request.

This design strengthens network security by ensuring that even if an attacker were to capture a ticket, the ticket's limited validity period and unique characteristics would render it useless for reauthentication purposes. This aspect of Kerberos significantly enhances the security framework in environments where authentication and prevention of unauthorized access are critical concerns.