Expand, slice, and aggregate CIDR ranges into hosts

mapcidr is the utility that sits between a list of network ranges and the scanners that work on individual hosts. Give it a CIDR like 10.0.0.0/24 and it expands the range into every IP inside it. Hand it a pile of scattered IPs and it aggregates them back into the smallest set of subnets that covers them. It is small, fast, and built to be one node in a longer chain rather than a tool you run on its own.

The operations go well past expand and aggregate. It can sort ranges, count how many IPs a CIDR holds, slice a large range into a fixed number of chunks or by host count, filter to only IPv4 or only IPv6, match or exclude IPs against a file, skip base and broadcast addresses, and shuffle the output so a scan does not walk a subnet in order. Each operation reads a list and writes a list, so they compose cleanly.

On Trickest, mapcidr is a Network node that takes a CIDR or a file of CIDRs and writes a file and a folder of results. It usually follows asnmap, which maps an organization's ranges, and feeds a port scanner like naabu, turning owned address space into the concrete host list those scanners need.