How to Find Open Ports on Your Network

Why Check Open Ports?

Every open port is a potential entry point for attackers. Open ports run services — and those services can have vulnerabilities. Regularly auditing your open ports is a fundamental security practice.

Method 1: Online Port Scanner

Use our free Port Scanner to scan common ports on any public IP or hostname without installing anything.

Method 2: Nmap

# Install Nmap
sudo apt install nmap       # Ubuntu/Debian
brew install nmap           # macOS
winget install Nmap         # Windows

# Scan top 1000 ports (default)
nmap 192.168.1.1

# Scan ALL 65535 ports
nmap -p- 192.168.1.1

# Scan specific ports
nmap -p 22,80,443,3389 192.168.1.1

# Detect service versions
nmap -sV 192.168.1.1

# Aggressive scan (OS + version + scripts)
nmap -A 192.168.1.1

# UDP scan (DNS=53, SNMP=161, NTP=123)
nmap -sU -p 53,123,161 192.168.1.1

# Scan entire subnet
nmap 192.168.1.0/24

# Fast scan with service detection
nmap -T4 -sV --open 192.168.1.1

# Run vulnerability scripts
nmap --script vuln 192.168.1.1

# Save results
nmap -oA scan-results 192.168.1.1

Method 3: Check Your Own Local Ports

# Linux — show all listening ports
netstat -tuln
ss -tuln

# macOS
lsof -i -P | grep LISTEN

# Windows
netstat -an | find "LISTENING"

# Show process using each port (Linux, requires root)
sudo ss -tulnp
sudo netstat -tulnp

Common Ports Security Reference