SYN

Short for synchronize, SYN is a TCP (transmission control protocol) packet sent to another computer requesting that a connection be established between them. If the SYN is received by the second machine, an SYN/ACK is sent back to the address requested by the SYN. Lastly, if the original computer receives the SYN/ACK, a final ACK (acknowledgment) is sent.

ACK, Computer abbreviations, Network terms, SYN attack