In this video, I demonstrate how to scan networks for open ports using Nmap. I first explain how the Nmap port scanning process works I then walk through several examples and share my 7 tips for scanning larger networks.

Here are the examples I go over in this video.

1. Scan top 1000 ports
2. Scan a single target system
3. Scan an entire network or IP range.
4. Scan top 100 ports
5. Scan specific TCP ports
6. How to scan a range or ports
7. How to scan UDP ports

Port Scanning Tips

1. Disable DNS lookups
2. Disable Host Discovery
3. Display progress
4. Use packet trace option
5. Display reason
6. Run ping scan first
7. Save output to text file.

You can use scanme.nmap.org to run tests scans. Do not run Nmap scans on production systems or networks without permission.

By default Nmap will do a host discovery process on target systems. Firewalls can block these packets which results in Nmap skipping the port scan. You might need to use the Pn command to treat all hosts online to force a port scan. I go over this in detail in the video.

Written instructions & examples
https://networkverge.com/portscanning'>https://networkverge.com/portscanning

More network and Nmap Tutorials
https://networkverge.com