rdesktop is an open source client for Windows Remote Desktop Services, capable of natively speaking Remote Desktop Protocol (RDP) in order to present the user's Windows desktop. rdesktop is known to work with Windows versions such as NT 4 Terminal Server, 2000, XP, 2003, 2003 R2, Vista, 2008, 7, and 2008 R2.

rdesktop currently runs on most UNIX based platforms with the X Window System, and other ports should be fairly straightforward.