The IANA (Internet Assigned Numbers Authority) maintains a CSV file with all known port assignments. PowerShell can download this list for you:
$out = "$env:temp\portlist.csv" $url = 'https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.csv' $web = Invoke-WebRequest -Uri $url -UseBasicParsing -OutFile $out Import-Csv -Path $out -Encoding UTF8
The result is a list with all the port assignments in object oriented format. You could then use this information for example to filter out specific ports:
Import-Csv -Path $out -Encoding UTF8 | Where-Object 'transport protocol' -eq 'tcp' | Where-Object 'Port Number' -lt 1000