In the Single Program environment or when ShofarNexus has sole control of a network interface hardware, an invisible network becomes possible.
There are many low level messages, such as Address Resolution Protocol or the TCP handshake that the Operating System will dutifully respond to.
This allows unknown machines or scanners to find that a given computer exists and then explore potential holes to allow access.
ShofarNexus makes a computer invisible by not responding to the low level messages, including the TCP handshake, so it’s presence cannot be detected. There are some messages, such as Address Resolution Protocol, that must be responded to for local network operation, but will only respond to necessary devices, such as a router.
Authorized computers are free to communicate as normal.
This is well beyond what firewalls provide and can be designed such there are essentially no configuration options on the invisible computer and therefore no configuration error to open a hole.