Sending data beyond port 65535?

[meoiswa]

Please help me figure out how is this happening o.o

I made a little program in love to spam udp packets on all ports and capture them on my server with ngrep to test firewall rules.
Doing some testing I forgot to stop the port at the "max" 65535 and the program kept "sending" data on further ports.
Then it happened, somehow my server recieved a packet on port 65659. How did it happen? how can it happen? if 65535 is not the max port then what is it?



I've tested it over and over and I can successfully send data to the server on that magical port.

[meoiswa]

And I found the answer, ports repeat after 65535, so port 65659 - 65536 (ports 0 to 65535) = 123, which is the open port in my firewall