IP Spoofing

Generally data is sent over network using IP addresses , in IP spoofing the hacker changes the IP address of destination to itself and behaves as if it is original destination also replies to the source to make it unknown about changes. Also he can just become source for original destination IP and become a mediator to pass data between them and use information he wants.

It is generally used for Denial-of-service attacks .In which the goal is to overwhelm the computer with traffic to stop its services. The attacker does not care about receiving responses to the attack packets. Packets with spoofed addresses are thus suitable for such attacks. They have additional advantages for this purpose they are more difficult to filter since each spoofed packet appears to come from a different address, and they hide the true source of the attack.

Any service that uses IP address for authentication can be vulnerable to this attack.You can use filtering techniques to defend against it such as: packet filtering, ingress filters, egress filtering.Also techniques like Reverse Path Forwarding, Hop count filtering, Path identification can help prevent such attacks up to some extent.