Remmina is a remote desktop client written in GTK+, aiming to be useful for
system administrators and travelers, who need to work with lots of remote
computers in front of either large monitors or tiny netbooks.

Remmina supports multiple network protocols in an integrated and consistent
user interface. Currently RDP, VNC, XDMCP and SSH are supported.

Please don't forget to install the plugins for the protocols you want to use.