Filtering Sources of Unwanted Traffic

There is a large and increasing amount of unwanted traffic on the Internet today, including phishing, spam, and distributed denial-of-service attacks. One way to deal with this problem is to filter unwanted traffic at the routers based on source IP addresses. Because of the limited number of available filters in the routers today, aggregation is used in practice: a single filter describes and blocks an entire range of IP addresses. This results in blocking of all (unwanted and wanted) traffic generated from hosts with IP addresses in that range.