It’s called having an IP address.
Everything on the Internet is subject to a near-constant stream of hacking attempts.
If you are addressable, someone is attempting to address you.
If I were to give that list of IP addresses to anyone wanting to do my company harm they could bring the entire factory to a screeching halt in seconds with a few key strokes and mouse clicks. It would take months to find the code insertions.
Didn’t even run the e-mail side under TLS. Bwahahahahaha.
I used to have some AV program that would alert you when you were pinged. I had to turn that part off because it was unrelenting.