What protocol is NTLM?

Windows New Technology LAN Manager (NTLM) is an outmoded challenge-response authentication protocol from Microsoft. Still in use though succeeded by Kerberos, NTLM is a form of Single Sign-On (SSO) enabling users to authenticate to applications without submitting the underlying password.

How does NTLM authentication works?

NTLM Authentication Process The user shares their username, password and domain name with the client. The client develops a scrambled version of the password — or hash — and deletes the full password. The client passes a plain text version of the username to the relevant server.

What is NTLM authentication used for?

The NTLM authentication protocols authenticate users and computers based on a challenge/response mechanism that proves to a server or domain controller that a user knows the password associated with an account.

Is RC4 NTLM?

The problem, according to the security company, is that Microsoft added support in Kerberos for an encryption algorithm called RC4-HMAC, which uses the NTLM hash as its key. Because of this, an attacker that can obtain a user’s NTLM hash, can also get a valid Kerberos ticket.

What port does NTLM authentication use?

NT LAN Manager (NTLM) is the default authentication scheme used by the WinLogon process; it uses three ports between the client and domain controller (DC): UDP 137 – UDP 137 (NetBIOS Name) UDP 138 – UDP 138 (NetBIOS Netlogon and Browsing)

How do I disable NTLM authentication?

To disable outgoing NTLM authentication traffic locally:

1. Run secpol. msc.
2. Browse to Security Settings\Local Policies\Security Options.
3. Set the Network Security: Restrict NTLM: Outgoing NTLM traffic to remote servers setting to Deny All.

What is the impact of disabling NTLM?

If you want to turn off NTLM audit policy settings, there will be a little impacts, that is when NTLM authentication is successful or failed, no audit events will logged in Security log under Event Viewer on any DC.

What kind of authentication protocols does NTLM use?

The NTLM authentication protocols include LAN Manager version 1 and 2, and NTLM version 1 and 2. The NTLM authentication protocols authenticate users and computers based on a challenge/response mechanism that proves to a server or domain controller that a user knows the password associated with an account.

How does the first step of NTLM work?

The first step provides the user’s NTLM credentials and occurs only as part of the interactive authentication (logon) process. 1. (Interactive authentication only) A user accesses a client computer and provides a domain name, user name, and password. The client computes a cryptographic hash of the password and discards the actual password.

Can a NTLM server be configured from Server Manager?

NTLM cannot be configured from Server Manager. You can use Security Policy settings or Group Policies to manage NTLM authentication usage between computer systems. In a domain, Kerberos is the default authentication protocol. The following table lists relevant resources for NTLM and other Windows authentication technologies.

How is the NThash used in net-ntlmv1?

NTLMv1 (A.K.A. Net-NTLMv1) About the hash. The NTLM protocol uses the NTHash in a challenge/response between a server and a client. The v1 of the protocol uses both the NT and LM hash, depending on configuration and what is available. The Wikipedia page on NT Lan Manager has a good explanation.