IP address spoofing

where an attacker alters the source IP address in a network packet to hide their identity or impersonate another computing system.

IP spoofing is used when someone wants to hide or disguise the location from which they're sending or requesting data online. As it applies to cyberthreats, IP address spoofing is used in distributed denial of service (DDoS) attacks to prevent malicious traffic from being filtered out and to hide the attacker's location.