I've done a bit of system administration in my day, and security is by far the hardest part. In essence, your are forced to keep your finger(s) in the dike, or at worst keep an eye on the water that is flowing trough it. One simple mistake can compromise your security. One slip up, or a little bit of laziness on your part, and you can be compromised. The malicious hacker only has to be right once. They can try exploits, probe ports, sniff packets. These thing can fail countless times, but it doesn't matter. Eventually they will find a week point in your damn, and the water will flood through. It is a simple fact that no security plan is foolproof.
This line of thinking led me to thoughts of the government's task of combatting terrorism. They have a much bigger and astronomically grander dike to keep their fingers in. There are thousands of gallons of water flowing through everyday that they have to monitor, and the price of failure on their part is much greater. They live with the burden of having to achieve a perfect record. One slip up, one mistake, and the cost is massive. The terrorist, on the other hand, needs only one success. They need to slip only one bomb on one plane, and they have won.
