Since the days of medieval castle design, architects have cleverly engineered concentric defensive layers along with traps, to thwart attackers, and protect the strong hold. Today many people still believe that the moat was a water obstacle designed to protect the outer wall, when in fact it was often inside the outer wall and structured as a reservoir to flood any attempt at tunneling in. Much like these kingdoms of old, today companies are leveraging similar design strategies to protect themselves from Internet attackers.The last line of defense is always the structure of the wall, and guards of the castle keep itself. Today the keep is your network server that provides customers with web content, partners with business data, and employee’s remote access. All traffic that enters your servers comes in through a network interface card (NIC). The NIC represents both the wall, and the guards for the castle keep. Your NIC should support a stateless packet filtering firewall application that is authorized to drop all unacceptable packets. By operating within both the NIC, and the kernel driver, this software application can drop packets from know Internet marauders, rate limit all inbound traffic, filter off SYN floods, and only pass traffic on acceptable ports. By applying all these techniques your server can be far more available for your customers, partners, and employees.
For the rest of the article, with several cool sections of code that explain how to protect your server, please visit Cyber Defense Magazine.