Interesting network share issue - Vista

[audiophile]

Scenario: 4 PC's. All in the same domain.

• pc #1, Windows XP Pro
• pc #2, Windows NT 4.0 domain controller
• pc #3 Windows Vista 64 ultimate
• pc #4 windows Vista 32 ultimate

Now up until about a week ago every single device could access each others shares no problems. No changes on any pc has been done. Windows Firewall has been turned off as well as defender where appropiate.

The problem i have now is that pc#4 is now started having issues with accessing a share on pc#3. Continually getting prompted for username and password. I have even tried an domain admin account which fails.


Pc#1 and pc#2 have no issues and are not prompted with username / password related promtps to access this share.

Pc#3 can access shares on pc#1, #2 and #4.

Anyone got any ideas on what is going on ?

 

[H2SO4]

If you can drive a packet sniffer, I'd suggest taking two traces and comparing them: one trace of a PC#4 to PC#3 access attempt which results in a prompt, and another in reverse that goes through without prompting.

It's not clear to me whether you're saying that access works, except you need to retype credentials every time, or whether it's "access denied" whatever you try. If its the former, it may come down to different LMCompatibilityLevel settings on the XP box and NT4 PDC compared to the two Vista machines. That's just a wild guess though, and a packet trace would tell you more about the differences between the "prompted" and "no prompts" access attempts.

 

[audiophile]

sorry XP to the vista machine works and no prompts.

Vista to Vista prompts and no matter what account i try, no access is granted.

 

[audiophile]

ok resolved the issue.

I had a rethink about the authentication mechanisms Vista uses and XP. The only difference was NTLM. XP would use an early version of NTLM whereas VISTA uses a newer version. Seeing I am on a NT 4.0 domain, i decided to in Both the #3 and #4 change the LAn authentication methods.

This is done in the local security policy (in the admin section)

I changed from NTLM2 to Send LM and NTLM use NTLM2 session if available.

Rebooted both Vista PC's and now it is all working.

 

[H2SO4]

The NTLM version settings controlled through policy map back to the LMCompatibilityLevel registry value.

I'm glad to hear it's working for you now.