Remmina is a remote desktop client that supports multiple network protocols — RDP, VNC, NX, XDMCP and SSH — in a nice and very user-friendly GUI.
In its basic usage, you only need to know the protocol, the server address, username and password.
This works perfectly if you are in the same LAN. For connections over the internet, Remmina can tunnel through SSH, configured in the SSH tab:
It supports RDP for Windows machines, VNC for Linux desktops, and NX for remote sessions. All saved in a single, clean interface.
Enjoy!