What packets are sent to establish a TCP session or “handshake”?

SYN, SYN+ACK, ACK

 

URG: Urgent Pointer field significant
ACK: Acknowledgement field significant
PSH: Push Function
RST: Reset the connection
SYN: Synchronize sequence numbers
FIN: No more data from sender

 

EVENT DIAGRAM
Host A sends a TCP SYNchronize packet to Host B

Host B receives A’s SYN

Host B sends a SYNchronize-ACKnowledgement

Host A receives B’s SYN-ACK

Host A sends ACKnowledge

Host B receives ACK.
TCP socket connection is ESTABLISHED.

tcp three-way handshake,syn,syn-ack,ack
TCP Three Way Handshake
(SYN,SYN-ACK,ACK)