[j-nsp] protect ssh and telnet

[Phil Shafer]

Vincent Bernat writes:
>On which attribute can SSH keys be served?

Apologies.  I shot my mouth off.  JUNOS does not currently support
this.  And RADIUS, being cleartext, is not suitable.

LDAP (w/ SSL) would be a better solution, using something like:

    https://github.com/AndriiGrytsenko/openssh-ldap-publickey

which plugs into openssh using the "AuthorizedKeysCommand" sshd_config
statement.  But JUNOS doesn't ship openldap, so the only way to
make this work would be an external web server can proxies requests
into LDAP.  The AuthorizedKeysCommand would be a script that makes
the HTTP request and formats the results.  The above LPK script
could be put inside a perl web framework like Mojolicious.

It's a bit of rough plumbing, but until we can ship openldap (or
you run the non-veriexec JUNOS), that's likely the best answer.

Thanks,
 Phil