Re: [tor-relays] does it make sense to close unused ports at a tor relay with iptables ?

The likes of GRC.COM <http://grc.com/> make you think that any port not blocked... is bad. I wondered why if nothing there

Because there is a difference between a closed port and a filtered port. Deny vs drop. The less of a fingerprint you offer to attackers, the better. It's security by obscurity to an extent, but even a response from a closed port can give away clues about the software, OS and network stack that's running.