tls-crypt is an OpenVPN feature that encrypts and authenticates control-channel packets before they reach the normal protocol logic. The control channel is where clients and servers negotiate sessions, exchange keys, and manage tunnel setup, so protecting it helps hide metadata and reject traffic that is not from a valid peer.
This matters because many VPN attacks begin with unauthenticated probing, packet flooding, or attempts to stress the handshake path. With tls-crypt enabled, OpenVPN can drop bogus control packets earlier, reducing exposure to scanning and some denial-of-service pressure. It does not replace full VPN authentication or fix application bugs, but it is a useful hardening layer in environments that depend on remote access. Defenders often enable it alongside strong certificates and current OpenVPN patches to make the control plane harder to target.