nmap says port is closed while nestat says it's listening

By default nmap doesn't scan all ports. try this one.

nmap -sT -sU -p- 127.0.0.1

linux port netcat nmap

@Satish, you don't need to add -sU which will scan the UDP ports too, and take a while.

nmap -v -p 8020 127.0.0.1

This should be enough and instant.

linux port netcat nmap

By default nmap scans only the well know ports.You specify a port by using the -p parameter.

To scan all ports : nmap -v -p "*" 127.0.0.1

To scan only port 8020 : nmap -v -p 8020 127.0.0.1

CodeHunter