NPS Server 2016 unable to use NLMV2

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Biju_Babu posted this 5 days ago

Hello,   I have installed NPS in Server 2016 and configured the policy with MS-CHAPv2 (also tried with PEAP, EAP etc..) and the authn is failing with event id 4625. NTLM v1 and LM is disabled in the domain .   It seems to be a known issue and documented the workaround in here - https://support.microsoft.com/en-us/help/2811487/lt2p-ipsec-ras-vpn-connections-fail-when-using-ms-chapv2 , but unfortunately it is not working in my case, my guess is that may be Server 2016 is not honoring that reg value.

  Any suggestions or thoughts?

    An account failed to log on.   Subject: Security ID: SYSTEM Account Name: servername$ Account Domain: Domain Logon ID: 0x3E7   Logon Type: 3   Account For Which Logon Failed: Security ID: NULL SID Account Name: blah123 Account Domain: Domain   Failure Information: Failure Reason: Unknown user name or bad password. Status: 0xC000006D Sub Status: 0xC000006A   Process Information: Caller Process ID: 0x3f4 Caller Process Name: C:\Windows\System32\svchost.exe   Network Information: Workstation Name: - Source Network Address: - Source Port: -   Detailed Authentication Information: Logon Process: IAS Authentication Package: MICROSOFTAUTHENTICATIONPACKAGEV10 Transited Services: - Package Name (NTLM only): - Key Length: 0   This event is generated when a logon request fails. It is generated on the computer where access was attempted.   The Subject fields indicate the account on the local system which requested the logon. This is most commonly a service such as the Server service, or a local process such as Winlogon.exe or Services.exe.   The Logon Type field indicates the kind of logon that was requested. The most common types are 2 (interactive) and 3 (network).   The Process Information fields indicate which account and process on the system requested the logon.   The Network Information fields indicate where a remote logon request originated. Workstation name is not always available and may be left blank in some cases.   The authentication information fields provide detailed information about this specific logon request. - Transited services indicate which intermediate services have participated in this logon request. - Package name indicates which sub-protocol was used among the NTLM protocols. - Key length indicates the length of the generated session key. This will be 0 if no session key was requested.

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MikeLeone posted this 5 days ago




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barkills posted this 5 days ago

What is the LMCompatibilityLevel on the client which fails?

 

Have you tried using an account local to the NPS server (instead of a domain account)?

 

Brian

 

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Biju_Babu posted this 4 days ago

I read some cases the reg entry fixed similar issues with 2012 NPS.



 

 

 

Regards

Biju

 

My working hours are from 2:00 PM IST to 10:00 PM IST (3:30 AM CST to 11:30 AM CST)

 

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Biju_Babu posted this 4 days ago

 

LMCompatibilityLevel  is

5 in client, NPS and DC



 

No, I didn’t. I will see if that is do-able , thanks.  



 

 

Regards

Biju

 



 

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barkills posted this 2 days ago

The first thing I thought when I saw the error message details was that it appears to be a computer (accountname=servername$) trying to authenticate to another computer using

the NTLM protocol family. That isn’t ever possible and will always result in a failure—computers can only authenticate to each other using Kerberos. You didn’t say where this error message was logged, but if it is the DC, then I’d wonder whether you’ve correctly

got the Kerberos pre-requisites setup on the NPS server (i.e. DNS, service principals--SPNs, time). Maybe there’s more to the error message, but I figured I should at least share that up front.

 

Other things that seem a bit odd in the error message:

 





  • Security ID:  The SID of the account that attempted to logon. This blank or NULL SID if a valid account was not identified - such as where the username specified does not correspond to a valid account

    logon name.


  • Key Length: Length of key protecting the "secure channel".  See security option "Domain Member: Require strong (Windows 2000 or later) session key".  If value is 0 this would indicate security option

    "Domain Member: Digitally encrypt secure channel data (when possible)" failed


 

These others seems less likely as the cause, but also worth looking into.

 

Brian

 

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Biju_Babu posted this 7 hours ago

Thanks Brian, appreciate it.  

 

Just to close the loop, it was an application side config issue.



 



 

 

Regards

Biju

 

My working hours are from 2:00 PM IST to 10:00 PM IST (3:30 AM CST to 11:30 AM CST)



 

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