That seems like the sort of thing that would have had a lot of HN attention over the years, but I guess not:

Ping Tunnel – Send TCP Traffic over ICMP (2011) - https://news.ycombinator.com/item?id=21009598 - Sept 2019 (1 comment)

https://news.ycombinator.com/item?id=512416 (March 2009)

Ping Tunnel - Send TCP traffic over ICMP - https://news.ycombinator.com/item?id=90196 - Dec 2007 (1 comment)