The zyxel sbg3300 n series applies acl rules stateful packet inspection spi denial of service dos and ddos features for first line defense against hackers network intruders and other harmful threats a configurable dmz provides more flexible accessibility while preventing external attacks on confidential databases the zyxel sbg3300 n series includes multiple wan interfaces for dsl ethernet and usb 3g4g adapters to establish wan backups or load balancing the wan backup provides cont