Ubuntu - nmap - Scan for a specific Port

Specify the port you want nmap to scan with -p option.

By default nmap scans only TCP ports.

sudo nmap -p 80 sharewiz.net

result:

Starting Nmap 6.40 ( http://nmap.org ) at 2016-07-08 00:53 BST
Nmap scan report for sharewiz.net (5.42.134.35)
Host is up (0.0016s latency).
rDNS record for 5.42.134.35: bbdp5.42.134.35.network.sure.com
PORT   STATE SERVICE
80/tcp open  http
 
Nmap done: 1 IP address (1 host up) scanned in 1.31 seconds