How to List All Ports in Use

Quick method: portrm scan

One command to see all ports, PIDs, process names, and commands across all operating systems:

$ ptrm scan
  PORT   PID     NAME           CMD
  22     1       sshd           /usr/sbin/sshd
  80     44219   nginx          nginx: worker process
  443    44219   nginx          nginx: worker process
  3000   67890   node           next-server
  5432   1234    postgres       /usr/lib/postgresql/16/bin/postgres
  6379   5678    redis-server   redis-server *:6379
  8080   19432   java           java -jar app.jar
  9090   42187   grafana        grafana server
  Found 8 ports in use

macOS: lsof

# All listening ports
$ lsof -i -P -n | grep LISTEN

# TCP only
$ lsof -iTCP -sTCP:LISTEN -P -n

# Specific port
$ lsof -i :3000

Flags: -P shows port numbers (not names), -n skips DNS lookup (faster).

Linux: ss (recommended)

# All listening TCP ports with process info
$ ss -tlnp

# All listening UDP ports
$ ss -ulnp

# Both TCP and UDP
$ ss -tulnp

# Filter by port
$ ss -tlnp sport = :8080

Flags: -t TCP, -u UDP, -l listening, -n numeric, -p show process.

Linux: netstat (legacy)

# All listening ports
$ netstat -tlnp

# Include UDP
$ netstat -tulnp

Install if missing: sudo apt install net-tools

Windows: netstat

# All listening ports with PIDs
> netstat -ano | findstr LISTENING

# With process names (elevated prompt)
> netstat -anob

Windows: PowerShell

# Clean table output
> Get-NetTCPConnection -State Listen |
    Select-Object LocalPort, OwningProcess,
    @{Name="Process";Expression={(Get-Process -Id $_.OwningProcess).Name}} |
    Sort-Object LocalPort |
    Format-Table -AutoSize

Comparison table

Filter by port range

# Show only dev ports (3000-9999)
$ ptrm scan --range 3000-9999

# With lsof (macOS/Linux)
$ lsof -i -P -n | grep LISTEN | awk '$9 ~ /:[3-9][0-9]{3}$/'