Definition
NTLM, or New Technology LAN Manager, is a legacy Microsoft authentication protocol used to validate user identities within a network. It operates using a challenge-response mechanism where the server sends a challenge to the client, which then encrypts it with the user's password hash and sends it back. This process allows systems to verify credentials without transmitting the password directly over the network. Understanding NTLM is crucial for network administrators and security professionals managing older Windows environments or integrating with legacy systems. For instance, it might be used for accessing shared folders on a Windows Server 2008 machine. While often confused with Kerberos, NTLM is less secure and more susceptible to certain types of attacks. It is a relevant topic for certifications like CompTIA Security+ and CISSP.