For Hayes modems, this wouldn't (well, shouldn't) have worked, since it requires a one second pause between the last '+' and the command. It's part of Hayes' patent IIRC. I believe it was also only processed on the transmitted traffic, not the received.
What does a competing and not-wanting-to-infringe-a-patent modem company do? They just don't implement the delay, and ignore the direction of the traffic while they're at it. Problem solved! (head-to-desk, repeatedly)
> I believe it was also only processed on the transmitted traffic, not the received.
I believe you're correct, although it's been ~25 years...
Which explains why the command above isn't exactly correct, IIRC. What you had to do was send a CTCP ECHO containing the "+++ATH0" to a channel -- or an individual user, but sending it to an entire channel full of people was a helluva lot more fun!
Anyways, I don't recall the exact command nowadays but it was
/CTCP #channel ECHO Goodbye +++ATH0
or something very similar.
As long as the "victim's" IRC client wasn't ignoring those CTCP commands, it would "echo" the text and, as expected, command their modem to hang up.
Perhaps it shouldn't have worked... but I promise you that it absolutely did.
(Also, you could do the same thing by putting the "command" into the payload of an (ICMP) "ping" -- and that's a completely different thing from the "ping of death" that was discovered in that same era.)
Direction was not ignored. People would be disconnected when their client replied to the DCC request or CTCP ping.
I'm not sure the vulnerable modems would ignore the delay because of patents. Would love if you have any reference. I remember a Smart Link softmodem respected the delay, but an Intel softmodem did not. Always assumed it was an implementation bug on the part of the Intel one.
Ping with embedded +++ATH worked too on some modems!
Of course you needed to have the nous to do this in the first place and a IRC server that showed users host names/ip adresses- I fear that I’m showing my age !
IIRC it worked against Microsoft WebTV set-top boxes. Some kids got in a lot of trouble by causing a bunch of them to hang up and dial 911 or something.
