Consider the following situation: In a LAN the router is configured to forward one incoming port from the WAN to a specific local ip-address/port.
My question is, how is the security in this situation impacted compared to a router, which does not perform port forwarding, when
- the ip-address configured for forwarding is not used in the LAN
- the ip-address configured for forwarding is available in the LAN, but no application is listening on the port
What are possible security risks/attack vectors for cases 1 and 2?