Expose a local TCP/UDP service to exactly one peer, no port forwarding, access expires automatically (open source, Rust)

Disclosure: I’m one of the developers. The problem: I wanted to let one specific person reach a service running on my machine (in this case an AI agent server bound to 127.0.0.1) without putting it on the public internet, touching the router, or handing out VPN access to my whole network. What ISEKAI portal does: - portal-server sits next to your service and only makes outbound QUIC connections. No inbound ports, no firewall/router changes. - You declare named services in a TOML file (e.g. a2a -> 127.0.0.1:3000). The client can only ask for those names, never arbitrary host:port. - Access is controlled by a Grant: "this one client key may connect, for 1/8/24 hours." When it expires, it's gone. - Peers without a Grant can't even see that a listener exists. - The connection starts relayed and can migrate to a direct path when possible. - Forwards plain TCP and UDP, so it's not tied to any one protocol. The write-up walks through a full demo: a Windows client talking to an A2A (agent-to-agent) sample server on a Linux box, where the server never listens on anything but localhost. Article: zenn.dev/seera/articles/9bb592ca7b575a Code (MIT): github.com/seera-networks/ISEKAI-link Prebuilt binaries for Windows / Linux / macOS (arm64) are on the Releases page. Honest caveats, since this sub will (rightly) ask: - It currently needs an account (Auth0 login; email, Google or GitHub) and traffic goes through our coordination/relay server. For organization accounts, we're planning to let you run your own dedicated relay, so traffic between your org's endpoints stays on infrastructure you control. - It's free right now while we run it as a public trial. When paid plans arrive, we intend to keep a free tier that covers a small number of endpoints, so homelab-scale use should stay free. I'd really like feedback, especially on how this compares to what you use today (Tailscale, Cloudflare Tunnel, ngrok, etc.) and what would make you trust it.