Kinho Kim contributed to the mapcidr repository by generalizing CIDR-based IP filtering for the -fi option, enabling support for arbitrary CIDR ranges beyond the default 0.0.0.0/0. He implemented a new helper function, cidrsToNetworks, and integrated it with mapcidr.RemoveCIDRs to enhance filtering flexibility and accuracy. Working primarily in Go, he also addressed a bug where the filter-ip flag was not correctly applied to CIDR inputs, adding robust validation to ensure only valid notations were processed. His work improved the reliability of IP address management and command-line interface operations, supporting more precise access control in production environments.