38 Project: Port Scanning

We’re going to do some port scanning!

NOTE: We’re only going to run this on localhost to avoid any legal trouble.

To make this happen, we need to install the nmap too.

MacOS:

brew install nmap

Windows WSL:

sudo apt-get update
sudo apt-get install nmap

1. Portscan All Common Ports

   This command will portscan 1000 of the most common ports:

   nmap localhost

   What’s the output?

2. Portscan All Ports

   This will scan all the ports–starting from 0 on:

   nmap -p0- localhost

   What’s the output?

3. Run a Server and Portscan

   Run any TCP server program that you wrote this quarter on some port.

   Run the all-port scan again (above).

   • Notice your server’s port in the output!

   • Does your server crash with a “Connection reset” error? If so, why? If not, speculate on why this might happen even if you didn’t see it from your server. (See the Port Scanning chapter for this!)