# fcidr
[](https://crates.io/crates/fcidr)
Fragmented Classless Inter-Domain Routing (FCIDR)
A library exposing a data structure to represent a set of CIDR ranges and
easily manipulate its entries using set-like operations.
This data structure can be applied, for example, in configuring firewalls that
*implicitly deny* (AWS Security Groups) using a rule set that explicitly
expresses rules for both allow and deny.
> **Note**
> Currently, only IPv4 is supported. IPv6 support is tracked by [#6](https://github.com/nicholaschiasson/fcidr/issues/6).