> Do not lock down to your IP address. > If SSH turns out to have a massive vulnerability that bypasses keyauth then every service on the net will be torn down

> Do not lock down to your IP address. > If SSH turns out to have a massive vulnerability that bypasses keyauth then every service on the net will be torn down those seem to contradict each other. i agree that black-/whitelisting should not be the center of you security architecture but it sure helps in the scenario of authentication bypass vuln.