How to connect to a device via LAN knowing its IP?

Question

Iron

Good afternoon! There is a monitor that can record different indicators. In the monitor settings there is an item about network settings, where it is indicated: IP address, subnet mask, gateway. I connect the motor to the PC via a network cable. In the TCP / IPv4 settings, I specify the subnet mask and gateway as in the monitor. Using NMAP, I do a ping scan of the monitor's IP address, as a result, it responds to the request. Next, I perform a TCP SYN scan of all ports (1-65535). As a result, NMAP gave me a list of all open ports. This is what I need, the monitor transmits melon data over an open port.
I took a monitor with the same functionality, only from a different company. I connect the motor to the PC via a network cable. In the TCP / IPv4 settings, I specify the subnet mask and gateway as in the monitor. Using NMAP, I do a ping scan of the monitor's IP address, as a result, it responds to the request. Next, I perform a TCP SYN scan, a TCP scan using the connect system call, various types of UDP scans, TCP NULL, FIN and Xmas scans, TCP ACK scans, TCP Window scans, Maimon TCP scans of all ports (1-65535 ). As a result, NMAP returned: ''All 65535 scanned ports are in ignored states.''
IP protocol scan returned: TCP, ICMP, UPD supported by the monitor.
How then to get information from the device if it is not possible to find out the port?

Answer 1

It is not necessary to keep the port open to transfer data. If the destination address is set, you can simply send UDP packets there without opening anything. Well, TCP, for example, open only for certain addresses.