A computer network sniffer is a security program designed for finding information being transferred over a computer network. Because of today's complex multi-topology, multi-protocol networks it is a good idea to have up-to date sniffer protection technology. This is where an Internal Intrusion (employee, somebody breaking in, pretending to be an employee) to a computer network can be extremely dangerous, because they could install a sniffer on the network to steal vital information (could be sold to business competitors). When a sniffer is successfully installed on a computer network they can be very hard to find and can be there for years.