Interesting how another server that identifies itself with the User Agent "facebookexternalua" has IPv6 addresses with ":face:" in it, like "2a03:2880:3ff:1::face:b00c". Not so nice that it seems broken and keeps requesting the same url over and over again around 10 times per second since yesterday, while circumventing caching. It is for now blocked.

(edit: I didn't even notice the "b00c" for "book"...)