Friday, 16 September 2011

Cannot access Windows 7 Shares from a Windows XP Machine

Scenario:
Windows 7 Machines x 4 (1 x Acting as a server)
Windows XP Machines x 3
10/100/1000Mbps Network.

So I replaced a Windows XP server with a Windows 7 one and there was me thinking this was going to be easy...

From the XP machines I could ping the 'server' but couldn't get onto it, both by UNC or IP paths. I believe the error was "The specified server could not perform this action" or something to that affect.

I did recall having an issue similar tp this with Windows7 in the past and turns out the resolution is the same. You have to disable SMB version 2 so 7 support back compatibility with XP Clients. (You also sometimes get the problem with Windows SBS 2008 and XP machines.)

In regards to how SMB is designed to work see below:
  • When a Windows Server 2008/Vista "client" connects to a Windows Server 2008/Vista "server", SMB 2.0 is used.
  • When a Windows Server 2008/Vista "client" connects to a Windows 2000/XP/2003 "server", SMB 1.0 is used.
  • When a Windows 2000/XP/2003 "client" connects to a Windows Server 2008/Vista "server", SMB 1.0 is used.
  • When a Windows 2000/XP/2003 "client" connects to a Windows 2000/XP/2003 "server", SMB 1.0 is used.

Resolution
To try disabling SMB2 (which is perfectly safe) enter regedit and navigate to the following key:

HKLM\System\CurrentControlSet\Services\LanmanServer\Parameters

Add a new REG_DWORD key with the name of "Smb2" (without quotation mark)
Value name: Smb2
Value type: REG_DWORD
0 = disabled
1 = enabled

A REBOOT IS REQUIRED FOR THIS TO WORK....


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Love to know how many other people this helps...