How Linksy's relay works, and why we still say no cloud
Linksy has no cloud. There's no account, and nothing you share is ever stored on a server. At home your devices talk to each other directly. Away from home, a small relay helps them find each other, and when two networks block a direct connection it forwards packets it can't read. It holds no keys, keeps nothing, and its code is open.
When is the relay used?
Only away from home. When your phone and computer are on the same Wi‑Fi, or joined by a USB cable, they connect to each other directly and the relay isn't involved at all. If the internet is down, Linksy still works at home.
Away from home means your devices are on different networks: the phone on mobile data at a café, the computer on your home Wi‑Fi. They have to find each other across the internet first, and that's the relay's job.
What does the relay actually do?
Three small things, and nothing else:
| Job | What crosses the relay |
|---|---|
| Introduces two of your devices so they can connect straight to each other (hole punching) | A few kilobytes, once |
| Tells a device its own public address | One small packet |
| Forwards packets when two networks block a direct connection | At most 16 KiB per second per device, by design |
That last limit is deliberate. It's enough for small things like the clipboard, a link, Ring or the battery level, and far too little for files, screens or the camera. Those go directly between your devices, so the relay never becomes a place your data flows through.
Why "a dumb forwarder" is accurate
Everything between two Linksy devices is encrypted end to end with QUIC and TLS 1.3, using keys your devices exchanged when you paired them in the same room. The relay never had those keys, so what it forwards is noise to it. It can't tell a clipboard from a ring, and it can't change a packet without the receiving device noticing.
| What the relay can see | What it can never see |
|---|---|
| A random key per device, with no name and no account behind it | Device names, files, clipboard, screens, camera, microphone |
| The IP addresses of devices connected to it | What was shared, or with whom |
| How many bytes it passed | Any encryption key |
It also keeps nothing. It logs warnings only, so no line per connection and no IP addresses on disk, and it stores nothing but its own TLS certificate. Its metrics are totals.
Whose relay is it?
It's the relay from iroh, an open-source networking library, run unchanged at a pinned version as a single program on an otherwise empty container. Linksy's copy runs at linksy-relay.diary.mg. Being open source, both what it does and what it doesn't can be checked by anyone.
Who can reach my devices through it?
Only your own paired devices. A device can connect from away only if it was paired with yours, and only for a week after they were last together on the same network or cable. Every time they meet again, the week starts over. Screens, control, the camera, the microphone and browsing files are refused from away unless you allow them for that device.
You can pair as many devices as you like. The first meeting always happens on the same network, because that's where they exchange keys safely. After that your phones, tablets and computers form a small network of their own, and any of them can reach any other.
Can I turn it off, or run my own?
You can turn away from home off entirely in the settings; Linksy then never contacts the relay. Running your own relay, and builds with no relay code at all, are planned for Linksy 0.14 on the public roadmap.