use strict; chomp(my @CIDR = ); foreach (@CIDR) { if (/\//) { # expand the address list my ($base, $range) = /(\d+\.\d+\.\d+\.)(.*)/; my ($r0, $r1) = split /\//, $range; if ($r1 < $r0) { die "invalid ip range" if length($r1) >= length($r0); $r1 = substr($r0, 0, length($r0) - length($r1)) . $r1; } print "$base$_\n" for $r0 .. $r1; } elsif (/-/) { my ($base, $from, $to) = /(\d+\.\d+\.\d+\.)(\d+)-\d+\.\d+\.\d+\.(\d+)/; print "$base$_\n" for $from .. $to; } else { # singular IP address print "$_\n"; } } __DATA__ 192.168.0.1 172.18.0.0/5 172.19.1.0/4 172.20.2.0/8 172.21.3.128/130 100.0.0.1-100.0.0.3 172.21.3.128/110