If you leave such programs running all the time, you take the risk that someone is going to use an exploit on you before you have a chance to apply a patch. For some purposes, this is an acceptable – even necessary – tradeoff, but it would be nice to enable them only when actually needed, to minimize the risk. And for other purposes, ssh et. al. are overkill. Perhaps you only really need to remotely initiate a limited set of operations. In this case, you don’t need a shell prompt, just a way to securely kick off scripts from elsewhere.Enter ‘Ostiary’. It is designed to allow you to run a fixed set of commands remotely, without giving everyone else access to the same commands. It is designed to do exactly and only what is necessary for this, and no more. The only argument given to the command is the IP address of the client, and only if the authentication is successful.