Thursday, April 06, 2006
Windows Vista and RDP

Windows Vista introduces a new 'Network Level Authentication' mechanism to RDP. It will be intereting to find out what they are doing there exactly, but meanwhile you might want to be able to use your legacy RDP clients to access your Vista desktop. Here is how you do this:

To configure Vista for the old RDP clients, go to Control Panel -> System -> Advanced System Settings. Select the "Remote" tab and then "Allow connections from computers running any version of Remote Desktop". That works - at the very least - good for mstsc.exe on Windows.

Here is a screen shot (Build 5342):



Now, the interesting thing would be to get this to work with rdesktop(1) and similar non-Windows RDP clients as well. Unfortunately, the latest Build 5342 is very uncooperative here. rdesktop fails miserably. Compare the TCP streams (upper one is rdesktop, lower one is mstsc.exe on Windows XP SP2):





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Thursday, April 06, 2006 2:00:47 PM (Eastern Standard Time, UTC-05:00)  #    Comments [2]  | 
Wednesday, April 26, 2006 6:50:19 PM (Eastern Standard Time, UTC-05:00)

The problem with rdesktop .vs. Vista is that rdesktop has a compile-time fixed modulus size for the RSA public key that comes from the server. If you hack the rdesktop source and change:

#define SEC_MODULUS_SIZE 64

to

#define SEC_MODULUS_SIZE 256

you can then connect to Vista.... but of course you can't use the same binary to connect to 2k3 or XP. A proper fix would need to detect the key size as the connection is setup.

Iain MacDonnell
Sunday, June 11, 2006 6:46:25 AM (Eastern Standard Time, UTC-05:00)
You seem to be talking about this bug, right?
http://sourceforge.net/tracker/index.php?func=detail&aid=1493188&group_id=24366&atid=381347

Why didn't you report your findings there? In the rdesktop team, we're more than glad to receive good bug reports, especially ones with full analysis of the situation :)
Ilya Konstantinov
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Copyright by Gerald Beuchelt.