Encoding IPv4 address and port number in IPv6 address: https://gitlab.com/-/snippets/3746764
Discussion
Is it an alternative to Tor?
No. It can be used to improve DNS seeds which share node addresses for bootstrapping.
Although I am not sure if others would agree with this approach to support nodes with non-default ports in seeders. Cc: nostr:npub1p23eukh0nxsqpfaakz6fj9vvj27y4gs0kevnrffdq4d4adkl7uuq7crnl6