scan port

$sudo apt-get install nmap

$nmap 127.0.0.1

Starting Nmap 7.60 ( https://nmap.org ) at 2020-02-20 15:32 CST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00013s latency).
Not shown: 998 closed ports
PORT    STATE SERVICE
22/tcp  open  ssh
631/tcp open  ipp

Nmap done: 1 IP address (1 host up) scanned in 0.14 seconds