NNCP is a package facilitating secure store-and-forward file and mail exchange. It can be thought of as a modern UUCP with Internet smarts.

NNCP supports direct online communication over a LAN or Internet, scheduled communication, offline copies, streaming communication (pipes), and more. It can therefore be used for air-gapped computers that might be communicated with by CD-ROM, tape, or USB stick. It can also be used for intermittent or on-demand links, very slow or high latency links, etc.

NNCP can build up ad-hoc friend-to-friend (F2F) statically routed, darknet, delay-tolerant networks for fire-and-forget secure reliable files, file requests, Internet mail and commands transmission. All packets are integrity checked, end-to-end encrypted, explicitly authenticated by known participants public keys. Onion encryption is applied to relayed packets. Each node acts both as a client and server, can use push and poll behaviour model. Also there is multicasting areas support.

Out-of-box offline sneakernet/floppynet, dead drops, sequential and append-only CD-ROM/tape storages, air-gapped computers support. But online TCP daemon with full-duplex resumable data transmission exists.