Attach: tmux & SSH tunnel

Attach is a tmux client for Android that connects over SSH.

Your shell runs on the server inside tmux, not on your phone. Attach speaks tmux
control mode (tmux -CC), so it drives that session as a real app: windows appear as
tabs, split panes are laid out and rendered natively, and scrollback belongs to the
pane rather than to a stream of escape codes.

Because the session lives on the server, leaving does not end it. Switch apps, lose
signal, or close Attach entirely — the shell keeps running, and reattaching puts you
back exactly where you were, with whatever was still running still running. Attached
sessions are held open by a foreground service while you are elsewhere, and a lost
connection can reattach on its own.

SSH PORT FORWARDING
Local (-L), remote (-R) and dynamic (-D / SOCKS) forwarding, run from the same app and
the same saved connections. Tunnels stay up in the background, and one connection can
depend on another — reach a private host through a jump server and Attach brings the
chain up in the right order. Optional auto-reconnect restores a tunnel after a network
drop.

THE TERMINAL
A VT100 terminal emulator with scrollback, text selection, adjustable fonts and colour
schemes, and a customisable toolbar for the keys a soft keyboard does not have — Esc,
Tab, Ctrl, arrows. CJK input and hardware keyboards are supported.

CREDENTIALS STAY ON YOUR DEVICE
Passwords and private keys are encrypted at rest with a key held in the Android
Keystore, hardware-backed where the device supports it. They are never written in
plaintext, never uploaded, and can optionally be locked behind your fingerprint or
screen lock. Authenticate with a password, a public key, or both. ed25519, ECDSA and
RSA keys are supported, and keys can be imported from files on your device.

HOST KEYS ARE CHECKED
Server host keys are pinned on first connection. If a pinned key ever changes, Attach
stops and shows you both fingerprints — it will not silently accept the new one.

CONNECT THROUGH A PROXY
Connections can be routed through a SOCKS5 proxy. Host key verification still applies
end to end.

WHAT YOU NEED
An SSH server you already have, with tmux installed on it for the terminal features.
Attach does not provide a server, and it has no user accounts or sign-in of any kind.

PRIVACY
Your connection details, credentials and terminal contents stay on your device and are
never sent anywhere. The app has no analytics or behavioural tracking. It does show
banner ads, which are non-personalised by default; you can change that in Settings,
along with crash reporting. Full details: https://attach-a2a68.web.app/privacy