Ping of death was already a thing two decades ago.
https://web.archive.org/web/19981206105844/http://www.sophis...
https://web.archive.org/web/19981206105844/http://www.sophis...
Everything was plaintext, including “authentication”, which was (at best) just asking the “ident server” on the same machine as your client who you claimed to be, which was considered sufficient because, after all, to run identd on its “privileged” low port meant you were an “administrator” (i.e. root of a unix machine).
I was behind NAT when I first got on IRC in ‘98. I set it up with ipfwadm.
I joined IRC in the early 90s, there was no NAT then, packet filtering was uncommon, and practically nothing on the Internet was encrypted. It was a very different time.