Ubuntu - nmap - Perform a tcp null scan to fool a firewall

sudo nmap -sN 192.168.1.69

result:

Starting Nmap 6.40 ( http://nmap.org ) at 2016-07-08 01:34 BST
Nmap scan report for peter-laptop-1 (192.168.1.69)
Host is up (0.000075s latency).
Not shown: 997 closed ports
PORT    STATE         SERVICE
80/tcp  open|filtered http
139/tcp open|filtered netbios-ssn
445/tcp open|filtered microsoft-ds
 
Nmap done: 1 IP address (1 host up) scanned in 97.33 seconds