After a client sends a connection request (SYN) packet to the server, the server will respond (SYN-ACK) with a sequence number of its choosing, which then must be acknowledged (ACK) by the client. This sequence number is predictable; the attack connects to a service first with its own IP address, records the sequence number chosen, and then opens a second connection from a forged IP address. The attack doesn’t see the SYN-ACK (or any other packet) from the server, but can guess the correct responses. If the source IP address is used for authentication, then the attacker can use the one-sided communication to break into the server.
What attacks can you successfully launch against a server using the above technique?
Denial of Service attacks
Session Hijacking attacks
Web page defacement attacks
IP spoofing attacks