I think this is something of a chicken and egg problem. The basic firewall UI is allow <computer> to use <port> for <incoming|outgoing>. This interface can be made very easy to use. The problem is that if this was the default then programs would simply not work, and users would not know why.
However, if it became standard, then programs would tell users to check their firewall, and can even tell users the information that they need to fill into the firewall (eg. name of computer, port, ...).
Conceivably, you could define an protocol for devices to request an opening. This protocol could include a way of sending the password.
However, if it became standard, then programs would tell users to check their firewall, and can even tell users the information that they need to fill into the firewall (eg. name of computer, port, ...).
Conceivably, you could define an protocol for devices to request an opening. This protocol could include a way of sending the password.