What is the port range for Minecraft LAN worlds?

I looked around and there doesn't seem to be an exact known range for the ports. I also noticed that different users usually have ports opened in different ranges (some report that their open port is always somewhere between 20000-25000, while you have it much higher).

You could open ports in a big range just to be sure, or, you could run a Minecraft server on your computer in which you can specify your own custom port which will always be used.

Here is my workaround for a similar situation.

First of all, I wanted to access the server over the internet and I wanted my friends to join again over the internet (all of us were located outside the LAN).
2nd I am running a lot of other services on the LAN and it is unacceptable for me to open port, moreover a range of ports.

I came across the service called Tunnel In - which is a tunneling provider and cloud port forwarder. The freemium plan allowed me:

1. Remotely access to my server, start Minecraft and learn about the port number
2. Create a secure tunnel and expose the Minecraft server through firewall without port forwarding and without compromising the security of LAN

Here is a nice post on how to allow Minecraft through firewall.