I've been searching the internet for a script/program that can automatically summarize CIDR classes that I pass to it. I haven't found one, but I found a perl module ( Net::CIDR::Lite ) that does just this. I wrote a small script that takes the CIDR classes and summarizes them and then outputs the summarized classes. This is useful for generating a routing table for a management server and basically you have to copy the classes from a router, summarize them and paste them on the server. Here's the script - copy/paste it in a perl file and make it executable: #!/usr/bin/perl use strict; use warnings; use Net::CIDR::Lite; my $ipv4String='[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'; if(defined $ARGV[0] && $ARGV[0] eq '-h'){ print "usage: $0 This script summarizes your IP classes (if possible). Input IPs with mask one per line. End with CTRL+D. Optionally, redirect a file to stdin like so: $0 < cidr.txt "; exit; } print "Enter IP/