whitelisted keys for dmsgpty access

[0pcom]

Currently, the only way to access a remote visor over dmsgpty is to set a remote hypervisor for that visor.

This is not always a desirable setup, as the remote visor will always attempt to connect to the hypervisor, and the hypervisor may not be online or may only be online intermittently.

We should have an alternative which is basically an explicit whitelist for dmsgpty access to that machine, entailing another config field.

I suggest the name 'dmsgpty_whitelist' for the config field.

Instead of the visor dialing to the keys listed there, it would simply accept connections from keys which are whitelisted, which would allow configuring remote access à la carte.

[0pcom]

solved / implemented