During testing of a test network, Paul sends TCP probe packets with the ACK flag set to a remote device and then analyzes the header information (TTL and Window Size). Paul is interested to know…

During testing of a test network, Paul sends TCP probe packets with the ACK flag set to a remote device and then analyzes the header information (TTL and Window Size). Paul is interested to know whether or not the port is open or closed. Analyze the scanning result below and identify the open port: 1: host 10.2.2.11 port 20: F!RST -> ttl: 60 win: 0 2: host 10.2.2.11 port 21: F!RST -> ttl: 70 win: 0 3: host 10.2.2.11 port 22: F!RST -> ttl: 60 win: 0 4: host 10.2.2.11 port 23: F!RST -> ttl: 90 win: 0