Spoofing is an attack that is done at the data link and network layers. Spoofing is an attack where an attacker will try to get one computer to pretend it is another computer in order to fool another system or part of the network into allowing the attacker to have the privileges of the spoofed computer.
Sequence number spoofing may be used for this type of attack. One type of spoofing is IP spoofing where an attacker may fake their IP address so the receiver thinks it is sent from a location that it is not actually from. There are various forms and results to this attack. One IP spoofing attack is a denial of service attack where the attack may be directed to a specific computer addressed as though it is from that same computer. This may make the computer think that it is talking to itself. This may cause some operating systems such as Windows to crash or lock up.