> https://owasp.org/www-community/pages/attacks/ip_spoofing_vi...
Isn't an actual technique, it's describing the observed result if the server were to blindly trust some HTTP headers which is just the application payload in a TCP stream. It's not spoofing the IP at any network layer.
> https://github.com/ParsaKSH/spoof-tunnel
Requires mutually agreed spoofing on both sides... at which point it's not really spoofing and also clearly not applicable because Wikipedia will not agree to it. (It is useful in the context that they're using it, just not at all what you're talking about)
Without controling a router that's on the path or being able to publish a route that contains the IP address you're trying to spoof, there is no way to spoof an IP address in bidirectional communication.