> UDP Based Character Generator Service
> When a datagram is received, an answering datagram is sent containing a random number (between 0 and 512) of characters (the data in the received datagram is ignored).
> The service only send one datagram in response to each received datagram, so there is no concern about the service sending data faster than the user can process it.
Oof...
Yeah apparently the idea that the "user" might not be the real sender wasn't yet well-known.
Simpler times indeed.
Maybe back then the designers still expected that hosts would always reply to unwanted packets with an ICMP error, so silently dropped packets were expected to be rare and always indicators of a connection fault?
Though I guess we can proudly say today that UDP:9 is the most widely deployed service on the internet...
Nowadays the well configured servers send ICMP errors only for the traceroute port range and the badly configured servers, which are more common, do not send any ICMP errors for unused ports.
The hardware that looks for the magic packet ignores the framing.
I certainly wouldn't run a TCP discard service, but making sure that UDP packets to port 9 do not result in any ICMP port unreachable response, or any other response, is a good practice.
bawolff•3mo ago
bux93•3mo ago