3 way handshake
TCP 3 way hadshake is a method to establish and brake down TCP socket connections.This is a connection oriented protocol. That’s why TCP uses specific control parameters as control bits:
* URG. Urgent pointer field significant
* ACK. Acknowledgement filed significant
* PSH. Push Function
* RST. Reset connection
* SYN. Synchronize sequence numbers
* FIN. No more data from sender
The protocol operation is as follow:
I can suppose that we have got a client host and server host. Client wants to stablish a comunication with the server.
Server is listen and waiting for a connection request from any remote client. This action is called passive open.
1 – Client send a connection request.
2 – Server has received a SYN from the client and it send back an aknowledgment.
3 – Client sends an ACK back to the server.
Connection is stablished till the client sends a FIN to end.
This is a capture taken with Wireshark
Checking frame by frame, you can see each flag: