For most of us, the threat is the exact opposite of a dedicated attacker. It's an opportunist (or automated system) that doesn't need to compromise every system

For most of us, the threat is the exact opposite of a dedicated attacker. It's an opportunist (or automated system) that doesn't need to compromise every system on the Internet. It just needs to compromise enough. You can compromise enough for almost any purpose without getting into getting past port knocking schemes.