tinc

tinc is a VPN daemon that creates an encrypted private network between hosts over the Internet by presenting the VPN as a regular network device, so existing applications can operate unchanged. It offers optional compression with zlib or LZO and uses LibreSSL or OpenSSL for encryption, authentication, and integrity protection through message authentication codes and sequence numbers. The software automatically builds a full‑mesh routing topology, sending traffic directly to the destination whenever possible, and supports NAT traversal provided at least one node has a reachable public address, even if that address changes dynamically.

Adding new nodes is done by supplying an additional configuration file, without restarting daemons or creating new interfaces. t inc can bridge multiple Ethernet segments, enabling LAN‑only applications and games to function across the Internet. It runs on a wide range of platforms—including Linux, the BSDs, macOS, Solaris, and various Windows versions—and fully supports IPv6 for both tunneling and operation over IPv6 networks.

The project is open source under the GPL v2 or later, maintained as a stable, free‑tier utility. Its design focuses on simplicity of deployment, automatic mesh routing, and cross‑platform compatibility, making it suitable for users who need a flexible, encrypted network that integrates transparently with existing software.