Before the connection would fail and log to trace without anything
particularly informative for the client (they just saw 'unexpected error'.
Provide a more informative behavior for the client.
Like self-signed TLS certificates, SSH host keys
warrant a similar security policy. This implementations
follows the lead of the TLS management and uses the same
policy name and interpretation, just storing the value
in 'pubkeys.ssh' for the node rather than an extensible
set of entry points (for now).
When a shell session is initiated, it registers
a recipient at the same time it would be trying
to establish session for not being a 'wait for
recipient'. Aggressively mark the state as connecting
to avoid the recipient erroneously thinking things have
not be set into motion yet. Additionally, have the ssh
plugin avoid a traceback when disconnecting before completing
connection.
Create a module that does ssh and treats it like
a console. The plan is to have a cliserver.py to
behave in a manner resembling consoleserver.py, but
with option to have multiple distinct sessions per
target.
