OK guys, here is a quick tip that might save you an hour or two.
If you rent a server on http://cal.sap.com and can’t connect with Eclipse, it is because the port 3390 is disabled by default. All you need to do is enable that port and voila!
Here is a screenshot of a configuration where the port is enabled:
Obviously, this port should be allowed on your firewall / router / etc as well.