That's what the firewall is for. I set up iptables rules on all machines that only allow fixed IPs on the local network access to specific ports. If you're run

That's what the firewall is for. I set up iptables rules on all machines that only allow fixed IPs on the local network access to specific ports. If you're running it over the public 'net, then I think Mongo and Redis allow for username/passwords and/or encrypted transit.