What does that port do?
Have you ever run lsof or netstat and wondered why a port was open, or what it does? This site is a useful way of checking: https://www.adminsub.net/tcp-udp-port-finder
It also contains a list of the most common attacks kown to be aimed at that port.
You can also look at the entries in “/etc/services”, however they are not guaranteed to be accurate as several ports are used for multiple activities and an attacker can also hide behind a well known port that is not currently in use for other things.