I started up a private minecraft server for my friend and I, and that required me to use generic TCP forwarding in order to open it up to accept his IP address. I used this program called serveo.io for the tcp forwarding that opened up my network to accept incoming connections. the command i use is this
ssh -R (portnumber):localhost:(localhost number) serveo.net
however, i'm also getting connections from random ip addresses i don't know such as this one
furthermore, i'm pretty sure i can catch viruses from having the ports i use open, even though I have OSX firewall and avast antivirus enabled. is there any way to whitelist my friend's ip address and block all the other ones? i'm relatively new to servers/port forwarding so it would be very helpful if someone could help explain that, as well as any other measures I should take to prevent receiving viruses/trojans/other malware over the internet.