D-Link DFL-CPG310 Product Manual - Page 258

Using SmartDefense In this field... Do this... Minimal MTU Size Type the minimum value allowed for the MTU field in IP packets sent by a client. An overly small value will not prevent an attack, while an overly large value might degrade performance and cause legitimate requests to be dropped. The default value is 300. Port Scan An attacker can perform a port scan to determine whether ports are open and vulnerable to an attack. This is most commonly done by attempting to access a port and waiting for a response. The response indicates whether or not the port is open. This category includes the following types of port scans: • Host Port Scan. The attacker scans a specific host's ports to determine which of the ports are open. • Sweep Scan. The attacker scans various hosts to determine where a specific port is open. You can configure how the NetDefend firewall should react when a port scan is detected. 242 D-Link NetDefend firewall User Guide