What breaks my whois on OS X?

Question

For some reason whois does not seem to work on my machine:

whois heise.de
whois: connect(): Connection refused
whois google.com
whois: connect(): Connection refused
whois cia.gov
whois: connect(): Connection refused
whois wikipedia.org
whois: connect(): Connection refused

As you can see the problem persists for different TLDs so it does not seem to be just a broken whois server.

I get the same results using each /usr/bin/whois or Network Utility.

For testing I disabled Little Snitch as well as the Apple Firewall.

Other networking tools like ping, nslookup etc. work fine.

Any other ideas?