"The robots currently at work knocking around for your guessable
password could easily be repurposed to guess your Unicode password
currently known as your port knocking sequence, and quite likely
have been already. Plus, we already have authpf(8) for
network-level restrictions on access.
"Whenever you write about security in general and SSH security
in particular (and for good measure also get slashdotted for your
efforts), the comments inevitably turn up a variety of useful and
less useful suggestions.
"The April 6th, 2012 article about the possible preparations for
a new round of slow bruteforcers was no different. Some of these
recurring ideas are worthy of some more attention, and a more or
less complete list is as follows - "