When using a port monitor, I noticed that the states of some of the connections where categorized as “unknown”. What does this mean?
It means that the connection state is unknown.
Upon further information:
I’m using Cport from Nirsoft.
A quick check of their documentation says “items with unknown state (the state column is empty) are displayed.” So my answer was actually more right than I realized. =) This means that no explicit state for the port is available. Probably meaning that it’s not explicitly denying the connection attempt; it’s just staying silent.
For further information you’d need to look through the source code, but since it’s not open source you’ll need to contact the vendor for deeper clarification.