How to share files between MAC and Windows 7?

Is it possible? Does Windows 7 & MAC file sharing work properly? If you’re at a LAN party and some of your friends use a MAC and you want to share files you will first have to tweak Windows 7 to send LM & NTLM responses! Read this tutorial to start transferring files between MAC and Windows 7!

How to share files between MAC and Windows 7

Quick Links:

A MAC might not the best gaming machine, although Valve is releasing more and more Steam games for MAC, but a MAC is great for working. Many design agencies use a MAC and not a Windows PC, although a Windows 7 PC looks far better than a MAC by now. If you want to share/transfer files between the two systems you have to modify the network security settings, enable the LM protocol and disable 128-bit encryption on Windows 7 or file sharing won’t work at all or if you are lucky only 1-way file sharing will work.

Important Disclaimer: You should only follow this guide to share files between a MAC and a Windows 7 PC. Undo the changes when you are done to guarantee optimal security on your Windows 7 PC. The LM protocol we use to share files between MAC and Windows 7 is considered to be a security risk, so I would not recommend to enable it permanently!

LM & NTLM authentication protocol

If you want to share files between Windows 7 & MAC you have to make sure that Windows 7 is sending LM & NTLM responses.

NTLM is a Microsoft authentication protocol and the successor of the LM hash a Microsoft authentication protocol that stores user passwords that are fewer than 15 characters long. The LM protocol is disabled by default on Windows Vista and Windows 7, so that you have to re-enable it in order to make file sharing between Windows 7 and MAC possible.

Enable Windows 7 MAC File Sharing via Security Policy Editor

1. Step Press Windows key + R
2. Step Enter secpol.msc to open the Local Security Policy Editor, scroll down until you see this:

Windows 7 MAC File Sharing Protocols

3. Step Double-click on the item Network security: LAN authentication level

From the dropdown select: Send LM & NTLM responses:
Send LM NTLM Responses MAC File Sharing
4. Step Click on Apply

5. StepDouble-click on Network Security: Minimum session security for NTLM SSP Based (including secure RPC) Clients

6. Step Uncheck the option “Require 128-bit encryption”:

Windows 7 Network Security

Sidenote: The default value of Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2 is: Send NTLMv2 response only. When you are done sharing file between MAC – Windows 7, undo the changes and revert back to the default setting.

Enable Windows 7 MAC File Sharing via Registry

If you are on Windows 7 Home Basic or Windows 7 Home Premium, you don’t have the security policy editor, so you have to modify the settings via the registry.

1. StepPress Windows key + R

2. Step Enter regedit.exe

3. StepUncollapse [HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LSA]

4. StepCreate a DWORD-key and name it LmCompatibilityLevel

5. StepEnter the value 0

Alternatively, you can download our registry key here:

Send LM & NTLM responses Registry key

Or copy the following text into a notepad, save it as a .reg file and execute it:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa]

“LmCompatibilityLevel”=dword:00000000

This tutorial is not complete, but should give you a first basic guide how to transfer files between a MAC and Windows 7. If you have anything to contribute to this tutorial please leave a comment. Especially MAC users are more than welcome to leave comments and add explanations what to do on the MAC to make file sharing possible.


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