grepcidr can be used as a stream filter when you need to compare a list of IP addresses against one or more
Classless Inter-Domain Routing (CIDR) mask specifications. Think of grepcidr as a CIDR-aware grep; instead of
using 'grep 1.2.3.4' you can use 'grepcidr -e 1.2.3.4/30', for example. Multiple specifications, of arbitrary mask
lengths, can be specified both on the command line or loaded from a file.