atopgpud listens to all network interfaces on port 59123 by default

[sfllaw]

I agree that using a unix domain socket for this local communication is a better option. Could you please create a separate issue for this?

Originally posted by @Atoptool in #334

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atopgpud listens on TCP port 59123, waiting for the atop client to connect to it: https://github.com/Atoptool/atop/blob/45744c60661cc926f9e972ac682b65026d93ab76/atopgpud#L54 https://github.com/Atoptool/atop/blob/45744c60661cc926f9e972ac682b65026d93ab76/atopgpud#L271-L276

This listens on all network interfaces, which seems a little excessive as a default.

I recommend that the default be a Unix domain socket, with a dedicated group that can connect to it.

If the admin actually wants to do remote atop, they should be required to pass a command-line flag like atopgpud --listen=0.0.0.0:59123.