small servers

 Pretty regularly we (the programmers in general) do make the small servers that sit on some random port and execute commands from the clients. With no security. We rely on the obscurity of the randomly (but not really randomly, since we usually choose it explicitly) chosen port, and usually also on the relative privacy of the development machines for security. And ideally, firewalls that forbid connections to random ports from the outside. But what if the machine is not very private (such as the tool gets run on a production machine), and the firewall doesn't forbid the connection? Someone else might connect. Then of course there is the obscurity of the tool's protocol, but if the tool becomes popular, its protocol becomes widely known. And then if the tool can access files, it easily becomes a target for attacks. So a little obscure tool can outgrow its breeches and become a security hole.

But it seems to be not that hard to fix with a helper library that would check the password on connection. It can automatically generate the password and put it into a file, and a client would read it from the file and supply on connection (like .Xauthority does). Maybe there even is already an existing library that does this?