that you don't understand?
You're on a mikrotik router (for example via winbox).
Now you need to check for port availability at some address (for example 1.2.3.4:945 or 5.6.7.8:1843)
I usually need to port scan some ridiculos DVR or printers or another stuff. And its annoing to make VPN connection for linux os, or come into local PC by temviewer to scan with nmap.
ROS is SO powerful, why it doesnt have so necessary network tool