grepcidr can be used to filter a list of IP addresses against one or more Classless Inter-Domain Routing (CIDR) specifications, or arbitrary networks specified by an address range. As with grep, there are options to invert matching and load patterns from a file. grepcidr is capable of comparing thousands or even millions of IPs to networks with little memory usage and in reasonable computation time.
grepcidr has endless uses in network software, including: mail filtering and processing, network security, log analysis, and many custom applications.
项目主页：http://www.pc-tools.net/unix/grepcidr/
下载地址：http://www.pc-tools.net/files/unix/grepcidr-1.4.tar.gz
来自:开源中国社区
