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That's fair. Of course that post also calls the OSI model "unfortunate" and "a poor approximation".

All models are wrong, some are useful.

Layer 4 to 7 is useful in this case, as layer 4 involves forging tcp/udp packets, which is vastly different than say a http level reverse proxy.

If you actually read ITU T-REC X.200, which specifies the OSI model, you'll find that it doesn't match the modern internet at all. E.g., we don't have an OSI-style transport protocol at all (connections themselves aren't addressable independent of the SSAPs), TCP and UDP are actually layer 5, the presentation layer is protocol-specific, and pretty much the entire stack falls to bits if the network layer isn't packet switched.

There's a separate term for the bits of the OSI model that are actually relevant; it's called the IETF model.

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