what is syn

"SYN" is a term used in computer networking that refers to a flag in the Transmission Control Protocol (TCP) three-way handshake used to establish a connection between a client and a server. During the handshake, the client sends a SYN packet to the server to initiate communication, and the server responds with a SYN/ACK packet to acknowledge the request and confirm the sequence number sent by the client. The client then sends an ACK packet to complete the handshake and establish the connection. A SYN flood is a type of denial-of-service attack that exploits the TCP three-way handshake by overwhelming the server with a flood of SYN packets without completing the handshake, causing the server to consume resources waiting for half-opened connections and making it unresponsive to legitimate traffic.