Multi-Machine Setup

PolyKybdHost supports a forwarder mode that lets a single PolyKybd serve multiple computers. The keyboard is physically connected to one machine, but the key displays reflect the active window on whichever machine you are currently using.

How it works

flowchart LR
    remote["<b>Remote machine</b><br/>PolyForwarder<br/>watches active window,<br/>sends window info"]
    keyboard["<b>Keyboard machine</b><br/>PolyHost<br/>owns HID device,<br/>updates displays"]
    kbd(["PolyKybd"])
    remote -- TCP --> keyboard -- USB --> kbd

• Keyboard machine: running PolyKybdHost in normal mode, physically connected to the keyboard
• Remote machine(s): running PolyKybdHost in forwarder mode (--host <IP>), no keyboard attached

When focus changes on a remote machine, it sends the window title and app info over TCP to the keyboard machine, which then updates the key displays.

Setup

1. On the keyboard machine: run PolyKybdHost normally:

   python -m polyhost

2. On each remote machine: run PolyKybdHost in forwarder mode, pointing at the keyboard machine’s IP address:

   python -m polyhost --host 192.168.1.100

   Or use a file containing the IP (useful if the address changes):

   python -m polyhost --host-file /path/to/host.txt

By default the forwarder uses the legacy plaintext TCP relay on port 50162. Make sure the keyboard machine’s firewall allows inbound TCP on that port.

Note

Check the Settings dialog or logs for the port number in use if you have changed it from the default.

Advanced: secured window-report RPC

For setups where you’d rather not expose the device-control surface over the network, there is an opt-in, authenticated window.report RPC path on port 50163. It is a separate listener from the default plaintext relay: it serves only window reports — it carries no device-control, firmware-flash, or bootloader access — and is gated by its own authentication key.

It is off by default. Enable it on the keyboard machine (via the window_report_network_enabled setting) and have the forwarder push to it with --report-rpc. The plaintext relay on port 50162 remains the default unless you switch.

Use case

A common setup: a desktop (with the keyboard) and a laptop. When you switch to the laptop and start typing, the forwarder detects the focus change and notifies the desktop. The keyboard displays update to reflect the laptop’s active app — all while the keyboard stays physically on the desk connected to the desktop.