Pretty simple script that will answer to what process is using a port.
PowerShell:
param(
[Parameter(Mandatory=$true)]
[string]$port #e.g. 443
)
# Pull PID from TCP Connections and then outputs process name(s)
$pids = (Get-NetTCPConnection | Where-Object { $_.LocalPort -eq $port }) | Select-Object -Property OwningProcess
$pids | ForEach-Object { Get-Process -PID $_.OwningProcess | Select-Object -Property Name }