The sniffer code is similar to the one used in the driver’s “tdip.sys” and “mstcp32.sys” and uses NT4 NDIS-4, XP NDIS-5 interfaces, targeting incoming traffic on Ethernet and VPN (ndiswanip) interfaces. It captures only directed packets (containing a destination address equal to the station address of the NIC). Packers-filtering engine rules may be set via DeviceIoControl messages. Filtered packets are stored in-memory until requested. Maximum packets storage list length is 128 items per filtering rule.