Unfortunately, no short term nor mid term plans for Linux support on spacedesk server.
Protocol specification is not publicly available.
You can only use your Linux machine as client via spacedesk HTML5 VIEWER http://viewer.spacedesk.net/.
Keep in mind that this HTML5 VIEWER app on Linux is much slower than our native apps on Android and Windows.
Dev’s should really take a note, the only solution at the moment to run a Linux Client is running the XP Version with Wine, as the HTML5 Version still lacks keyboard support! It’s really time to bring a Linux Version, maybe a “Wine port” would already do the job well!