  The distributed denial of service (DDoS) attack is detrimental to businesses
and individuals as we are heavily relying on the Internet. Due to remarkable
profits, crackers favor DDoS as cybersecurity weapons in attacking servers,
computers, IoT devices, and even the entire Internet. Many current detection
and mitigation solutions concentrate on specific technologies in combating
DDoS, whereas the attacking expense and the cross-defender collaboration have
not drawn enough attention. Under this circumstance, we revisit the DDoS attack
and defense in terms of attacking cost and populations of both parties,
proposing a joint defense framework to incur higher attacking expense in a grid
of Internet service providers (ISPs), businesses, individuals, and third-party
organizations (IoT Grid). Meanwhile, the defender's cost does not grow much
during combats. The skyrocket of attacking expense discourages profit-driven
attackers from launching further attacks effectively. The quantitative
evaluation and experimental assessment reinforce the effectiveness of our
framework.
