"Discard" Protocol (TCP/UDP port 9) not yet there
Description
There is a fairly old network protocol called "Discard", RFC 863: https://www.rfc-editor.org/rfc/rfc863. It simply discards everything that is sent to the server. The UDP/TCP port is port number 9: https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml.
This protocol is not detected yet by Wireshark. (I know, that this won't be used by many people at all. Hence it's definitely not crucial to implement. ;))
Sample capture
I did a few basic runs of this protocol against a Cisco router 2811 with IOS version 15.1(4)M12a with "service udp-small-servers" and "service tcp-small-servers" enabled. You can find those packets with a display filter of tcp.port eq 9 or udp.port eq 9. I did it for legacy IP and IPv6, both for TCP and UDP. (UDP for IPv6 was not listening on the server, though.)
As far as I understood, every TCP packet is simply ACKed, while UDP is silently dropped. Should be fairly simple to add this dissector, since it might only match on the port number 9.
