Dropbox unterstützt keinen NTLM Proxy Server

Allow Dropbox to authenticate with an NTLM proxy server
Dropbox does not support NTLM authentication and is incompatible with many corporate networks. You can vote for this feature to be added by visiting https://www.dropbox.com/votebox/248/support-for-ntlm-proxy-server

Mac users
This article and the instructions provided apply to Win32 environments (Windows XP, Vista, etc.). Mac users should check Authoxy http://www.hrsoftworks.net/Products.php following the instructions provided with the installer.

Win32 users
Following the directions below may upset your network administrator. This has only been tested with ISA server 2004 with *getdropbox.com whitelisted.

Download Cntlm

Install Cntlm
Unzip the contents of the download and run setup.bat

Configure Cntlm
Navigate to C:\Program Files\Cntlm
Open cntlm.ini in notepad
Change the following:
Username Your_Username
Domain Your_Domain
Password Your_Password
Proxy Your_Proxy’s_IP:Port (probably 8080)
Place a # infront of the second proxy.
Save cntlm.ini
Go to services and start the Cntlm service

Set Auth and get password hash
Open up CMD and navigate to the Cntlm folder
CD C:\Program Files\Cntlm
Type cntlm -M http://www.getdropbox.com
If that does not work try cntlm -M http://www.google.com
You should see an output like this:

[ Profile 0 ]

Auth NTLMv2

PassNTLMv2 72F78A2B364583291090E919B5CE9E04
Auth NTLMv2 <– Replace the whole #Auth line in cntlm.ini with this
PassNTLMv2 72F78A2B364583291090E919B5CE9E04 <– Replace the whole password line in cntlm.ini with this
Save cntlm.ini
Restart the cntlm service.

Configure Dropbox
Open dropbox preferences
Choose network tab
Select Manually enter proxy settings
Server Port 3128
Hit OK.

<edit>Instructions seem to work up to the part that says „Run cntlm with the -M flag to find your settings“. cntlm does not have a -M flag. Also, ccntlm.ini does not have an Auth line!
<edit> Cntlm does have an -M flag, make sure you use -M not -m.
cntlm.ini does have an auth line look for the line #Auth LM
<edit> If the cntlm service starts but stops immediately, try rebooting the computer.
<edit> If the cntlm service starts but stops immediately, make sure you installed cntlm to the default path (%PROGRAMFILES%\Cntlm). The service apparently searches for cntlm.ini in this directory. If you used a different path you can move cntlm.ini to the default path (usually c:\Program Files\cntlm\).

Proxy type should be (or remain) HTTP