IP spoofing occurs at the network layer, which is Layer 3 of the Open Systems Interconnection (OSI) model. This is because IP spoofing involves modifying the source IP address within the IP packet header, a function of the network layer. The attacker crafts packets with a forged source IP address, making it appear as though the packets originated from a different source. Since the manipulation happens at Layer 3, there are no external signs of tampering, and the spoofed requests appear legitimate.
Multiple sources confirm this:
- Reference 1: "These attacks are carried out at the network layer -- Layer 3 of the Open Systems Interconnection communications model."
- Reference 8: "This is because IP spoof attacks are carried out at the network layers – i.e., Layer 3 of the Open System Interconnection communications model."
- Reference 9: "All the gigantic headline-grabbing attacks are what we call "L3" (Layer 3 OSI)."
- Reference 11: The next hop IP address is that of the layer 3 switch's IP on the transit VLAN, further implying that spoofing exploits Layer 3 functionality.
While some security measures might address the consequences of spoofing at higher layers (like application-level checks), the fundamental act of manipulating the source IP address is a Layer 3 operation.
