Sentinel Proxy should require and send *Device token* as well as device *serial number*. Foris is responsible to generate such token (turris/foris#158). Please discuss with @shenek required format (I suggest something like 32-bytes hex/base64 string). This token is potentially confidential, so it would be better to pass it via a *file*, *stdin* or an *environment variable* in *init* script. The `device_token` shall be read from `/tmp/etc/sentinel/proxy.ini` generated by *init script*. We will preserve the option to pass it via cli argument for debug purposes. See /turris/turris-os-packages#518