Definition - What does Syn Flooding mean?
SYN flooding is a type of network or server degradation attack in which a system sends continuous SYN requests to the target server in order to make it over consumed and unresponsive. It is used by a hacker or a person with malicious intent to restrict the target system in fulfilling user requests and / or eventually crashing it.
SYN flooding can also be called a SYN attack.
Techopedia explains Syn Flooding
SYN flooding is primarily a type of denial of service (DoS) attack that utilizes a successive stream of SYN requests. In a typical scenario, the attacker sends SYN requests on each port of the server. The server in turn has to respond to each of the requests with an acknowledgment (ACK) packet from open ports and reset (RST) packet from all closed ports. Similarly the attacker / hacker has to respond back with an ACK packet to the server, but it doesn’t and keeps the connection open, along with sending further SYN requests / packets to the server. Therefore, due to the large and ongoing number of fake or unnecessary SYN, and its responding ACK packets and their open connections, the server gets busy and is then unable to service legitimate requests.