I needed to remove Little Snitch from a system that wouldn't boot (hence, couldn't use the uninstaller) and accomplished it by logging in to Single User Mode (hold down Cmd+S) then mounting the drive and running commands from a script posted at apple.stackexchange.com/questions/56481/remove-little-snitch-via-script
I have been searching for days trying to find what app I have installed thats using or used port 23515. I have tried checking in terminal with the simple netstat command, and found nothing. I've used little snitch to see if any programs are using that port, still nothing. Im a little lost and sadly the company is also lost and has no advice.