Editing IP address spoofing (section)

==Legitimate uses==
The use of packets with a false source IP address is not always evidence of malicious intent. For example, in performance testing of websites, hundreds or even thousands of "vusers" (virtual users) may be created, each executing a test script against the website under test, in order to simulate what will happen when the system goes "live" and a large number of users log in simultaneously.{{cn|date=May 2025}}

Since each user will normally have its own IP address, commercial testing products (such as [[HP LoadRunner]], [[WebLOAD]], and others) can use IP spoofing, allowing each user its own "return address" as well.{{cn|date=May 2025}}

IP spoofing is also used in some server-side load balancing. It lets the load balancer spray incoming traffic, but not need to be in the return path from the servers to the client. This saves a networking hop through switches and the load balancer as well as outbound message processing load on the load balancer. Output usually has more packets and bytes, so the savings are significant.<ref>{{Cite web|url=https://www.ra.ethz.ch/cdstore/www7/1899/com1899.htm|title = Network Dispatcher: A Connection Router for Scalable Internet Services}}</ref><ref>{{Cite web|url=https://www.ibm.com/docs/en/was-nd/9.0.5?topic=use-dispatcher-component|title = Dispatcher component| website=[[IBM]] }}</ref>