Hack the Route Start free Open app TCP connections
Three-way handshake
SYN, SYN-ACK, ACK: how TCP opens a connection, each side agreeing on starting sequence numbers.
The client asks (SYN), the server agrees and acknowledges (SYN-ACK), the client acknowledges (ACK); then data flows. Each side closes its direction with a FIN. Options like the MSS and window scaling are agreed in the SYNs.