Wanted to run a TCP portscan. Clicking the respective tool brings me always back to the original page. Whats wrong with this link? Happens also for UDP scan and troyan scan.

Hi sidi100, and Welcome to CC!

You are correct - some tools are temporarily unavailable. There has been a tremendous amount of work going on behind the scenes to make sure we provide the best service for our members and guests. On the way, some things (such as the port scans you mentioned) may have to wait a little while for attention.

In the meantime you could pop over to http://www.grc.com/default.htm and scroll down to the ShieldsUP service. This is a thorough test for all your ports and provides helpful advice on how to deal with an unsatisfactory result.