ssh, scp, sftp and vnc are frequently used tools (both servers and clients) on Linux. We may want to remote control a Linux box from Windows such as when we make demostration in a meeting while our work are done on the Linux box. There are lots open source SSH, SCP, SFTP and VNC clients for Windows to remote control Linux. This is a selection of these tools that are portable, which is important since we don’t always have Administrator access on the Windows clients.
Direct download: PuTTY
SCP and SFTP
Direct download: WinSCP
Direct download: TightVNC
Another option is the free RealVNC free client (not open source) which can pass the special keys (such as Alt+Tab) to the server : download RealVNC viewer.
On Mac OSX, you may consider the Chicken VNC client.