How to scan the ports on the machine?

1. Verifying Which Ports are Listening :
nmap -sT -O localhost/remote host/subnet

2. Check the port http of your local network :
nmap -v -p 80 192.168.1.*

3. ping scan :-
nmap -v -sP 192.168.2.0/24 or nmap -sP 192.168.2.*

4. UDP scan :-
nmap -v -sU 192.168.2.0/24

5. O.S Detection scan :-
nmap -O --vv 192.168.2.0/24

6. To check which protocol is supported by the remote machine :-
nmap –sO hostname