While there are no perfect solutions, and indeed there are some costs, there is at least one straightforward technical approach that can reduce the hazards associated with these attacks at minimal cost. Like a postcard, each message on the Internet, known as a packet, contains the addresses of both the sender and recipient. Reports of recent DDoS attacks indicate that the sender's address, referred to as the originator, or source, address, has often been forged - a process known as IP spoofing. Forging an originator address serves to confuse the trail leading back to the computer that sent the packets. In the real world, we have already found solutions to deal with different types of fraud, including forgery, by requiring intermediaries to vouch for their principal's authenticity.
Stockbrokers are subject to such rules when trading securities on behalf of clients.
Brokers are required to make good on trades, even if the customer fails to deliver the funds or securities involved. This rule ensures an orderly market and acts as a discipline on member firms. Similarly, airlines are required to check passengers' passports and other documentation before international flights. If a passenger's papers are not in order when the passenger arrives at his destination, he must be returned to the point of origin at the airline's expense. It's not foolproof, such measures are reasonably effective.