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The Handshake#

When two computers want to talk to each other (the client and the server), and they know to use TCP ahead of time, they establish a connection using a three-way handshake. It goes a little something like this:

  1. SYN: The client sends a SYN TCP packet to the server
  2. SYN-ACK: In response, the server replies with a SYN-ACK TCP packet
  3. ACK: Finally, the client sends an ACK TCP packet back to the server

There are three steps, which is why it's called the three-way handshake.