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TCP Handshake Sequence

Network Drawings2.png

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Step 2
  • ACK=1 increased (from 0 to 1) because of SYN=1 in Step 1.
Step 3
  • SEQ=1 because of ACK=1 in Step 2
  • ACK=1 increased (from 0 to 1) because of SYN=1 in Step 2
Step 4
  • ACK=1, SEQ=1 remain the same because no additional data has been yet exchanged.
  • Client sends 76 bytes of data to the server.
Step 5
  • ACK=77 because server received 76 bytes of data
  • Client's next sequence number will be SEQ=77
  • SEQ=1 remains the same because ACK=1 in Step 2
Step 6
  • For the first time server sends us non-zero length segment (264 bytes)
  • ACK=77 remains the same because LEN=0 in step 5
  • SEQ=1 because of SEQ=1 in Step 5
Step 7
  • SEQ=77 because of ACK=77 in Step 6
  • ACK=265 because we received 264 bytes of data
Step 8
  • Client initiates closing down the TCP connection
  • ACK=77 and SEQ=265 passes unchanged because LEN=0 in step 7
Step 9
  • SEQ=265 because ACK=265 in Step 8
  • ACK=78, increased by one because of FIN=1 and LEN=0 in Step 8
Step 10
  • SEQ=78 because of ACK=78 in Step 9
  • ACK=266, increased by one because of FIN=1 and LEN=0 in step 9

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