Implement the soporteremoto-feed package for libremesh

[germanferrero]

The package should implement:

• Installation of public certificate on pendrive plug.
• Acceptance or rejection of ephemeral ssh keys announced on shared-state.
• Contemplate persistence of soporteremoto configuration. We don't want to lose this configuration if the rpi gets broken. Maybe distributing and persisting the config on each node will help.

[germanferrero]

Implement the soporteremoto-feed package for libremesh #14

This package contains all the necessary software for a librerouter
to be included in a soporteremoto network, and receive support
in consecuence.

Installation of access-keys-signer certificate.

Unit Test:

• Action: I do plug a pendrive with a pubCert file on it to the LR.
• Result: The access-keys-signer gets written on /etc/config/soporteremoto

Installation of access key

Unit Tests:

• Happy Path
  • Context:
    • access-keys-signer installed.
    • shared-state soporteremoto table with new (not installed) access-key signed with the access-keys-signer.
  • Action: execute script that reads shared-state soporteremoto table.
  • Result: the new key is added to ssh-client authorized-keys.

• Not certificate installed.
  • Context:
    • access-keys-signer not installed.
    • shared-state soporteremoto table with new access-key.
  • Action: execute script that reads shared-state soporteremoto table.
  • Result: the new key is not added to ssh-client authorized-keys, a log is written to be consumed in the future with prometheus.

• Certificate installed malicious key.
  • Context:
    • access-keys-signer installed.
    • shared-state soporteremoto table with new malicious bad signed access-key.
  • Action: execute script that reads shared-state soporteremoto table.
  • Result: the new key is not added to ssh-client authorized-keys, a log is written to be consumed in the future with prometheus.