A native iOS terminal for your own machines. Tether connects over SSH to zmx — a persistent session manager on the host — attaches a session, and renders the live shell. Because zmx owns the sessions on the host, they keep running when you close the app, lose signal, or reboot the phone. Tether is a pure client: no server to run, nothing exposed but SSH.
v5 rewrite. Earlier Tether ran a Bun server with a custom Noise transport plus desktop and web clients. v5 drops all of it for a single native iOS app over SSH. The only host-side piece is
tether-notify, a tiny tool for push.
- Persistent sessions — the shell lives in
zmxon the host. Disconnect, background the app, reboot the phone: the session (and whatever runs in it) is still there when you reattach. - A real terminal — full VT emulator (TUIs, box drawing, CJK / emoji) on SwiftTerm, rendered natively. Live session switching, per-session working directory, scrollback history you can select and copy.
- On-device key vault — generate ed25519 keys in the Keychain, import or paste existing ones, see each key's SSH randomart and fingerprint. Private halves never leave the device except in memory, to libssh2.
- Trust on first use — an unknown host key is pinned on first connect; a later change is refused.
- Built in — git diff of the session's working directory, send a file or photo (SCP), kill a session, and encrypted push when an agent needs you.
The app is built from source and installed to your device (there is no public distribution). You need a Mac with Xcode 26 or later.
xcodebuild build \
-project clients/apple/Tether.xcodeproj \
-scheme TetherIOS \
-destination 'generic/platform=iOS Simulator' \
-configuration Debug \
-skipPackagePluginValidation \
CODE_SIGNING_ALLOWED=NOSee clients/apple/README.md for signing and on-device install.
On first launch: add a machine (host, port, user, and a key from the vault), then open it. The app attaches an existing zmx session if the host has one, otherwise it starts default.
Each host needs zmx (the session manager the app attaches to) and — optionally, for push — tether-notify.
Push (tether-notify). A phone registers its APNs token and a per-device AES key (generated on the phone, sent over SSH) and tether-notify encrypts each notification to that key, posting only ciphertext to a shared relay. The relay and Apple never see the plaintext; the iOS Notification Service Extension decrypts it on arrival.
bash install.sh # build + install tether-notify to ~/.local/bin (needs Go)
bash scripts/install-agent-hooks.sh homelab # notify from agent hooks (waiting / done)The app registers your phone automatically the next time it connects. Then any tool — a coding agent's hooks, a long job — can raise a notification:
tether-notify notify --title "homelab · agent" --body "Waiting for input" \
--link "tether://session/default?host=homelab"Agent hooks also record each session's state (working, waiting, done) with
tether-notify state; the app reads it with tether-notify status to badge sessions.
A waiting/done push is skipped while any zmx client is attached to that session —
including a desktop terminal. The app detaches 15 s after it goes to the background, so
a locked phone gets its pushes. As a backstop for an app killed while attached, set
ClientAliveInterval 30 / ClientAliveCountMax 2 in the host's sshd_config.
clients/apple/ native iOS app (TetherKit package + TetherIOS + NSE)
apps/tether-notify/ Go host CLI for encrypted push
install.sh build + install tether-notify
scripts/ install-agent-hooks.sh, release.sh
Architecture, data flow, and conventions: CLAUDE.md.
Transport is SSH — there is no shared password and no setup flow that skips host-key verification. Keys live in the iOS Keychain and reach libssh2 in memory only. A host-key mismatch fails loudly. The push relay only ever routes ciphertext it cannot read. Keep hosts reachable over your LAN, a tunnel, or plain SSH as you already do.