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Author(s) Olivier Bonaventure
Deadline No deadline
Submission limit No limitation
Category tags TCP

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Reordering the segments exchanged on a connection

TCP, as explained in the TCP chapter of Computer Networking: Principles, Protocols and Practice includes a sequence number in each segment that carries data.


Reorder the segments

During this connection, the client sent some data that was acknowledged by the server. Can you reorder the segments based on their sequence numbers and acknowledgements ? The trace starts at the third ack of the three-way handshake sent by the client to the server.

# Length Summary Status
0 20 bytes Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678594, Len: 0
1 22 bytes Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678592, Ack: 3164923749, Len: 2
2 20 bytes Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678592, Len: 0
3 20 bytes Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678588, Ack: 3164923749, Len: 0
4 22 bytes Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678590, Ack: 3164923749, Len: 2
5 20 bytes Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678590, Len: 0
6 20 bytes Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678596, Len: 0
7 22 bytes Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678594, Ack: 3164923749, Len: 2
8 22 bytes Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678588, Ack: 3164923749, Len: 2

0000  04d2d1ccbca4e765  8626a14250107080  
0010  00000000                            

0000  .ÒÑ̼¤çe.&¡BP.p.
0010  ....            
  • Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678594, Len: 0
    • Source Port: 1234
      • Destination Port: 53708
        • Sequence number: 3164923749
          • Acknowledgment number: 2250678594
            • 0101 .... = Header Length: 20 bytes (5)
              • Flags
                • 000. .... .... = Reserved: Not set
                  • ...0 .... .... = Nonce: Not set
                    • .... 0... .... = Congestion Window Reduced (CWR): Not set
                      • .... .0.. .... = ECN-Echo: Not set
                        • .... ..0. .... = Urgent: Not set
                          • .... ...1 .... = Acknowledgment: Set
                            • .... .... 0... = Push: Not set
                              • .... .... .0.. = Reset: Not set
                                • .... .... ..0. = Syn: Not set
                                  • .... .... ...0 = Fin: Not set
                                  • Window size value: 28800
                                    • Urgent pointer: 0
                                    0000  d1cc04d28626a140  bca4e76550187080  
                                    0010  00000000330a                        

                                    0000  ÑÌ.Ò.&¡@¼¤çeP.p.
                                    0010  ....3.          
                                    • Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678592, Ack: 3164923749, Len: 2
                                      • Source Port: 53708
                                        • Destination Port: 1234
                                          • Sequence number: 2250678592
                                            • Acknowledgment number: 3164923749
                                              • 0101 .... = Header Length: 20 bytes (5)
                                                • Flags
                                                  • 000. .... .... = Reserved: Not set
                                                    • ...0 .... .... = Nonce: Not set
                                                      • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                        • .... .0.. .... = ECN-Echo: Not set
                                                          • .... ..0. .... = Urgent: Not set
                                                            • .... ...1 .... = Acknowledgment: Set
                                                              • .... .... 1... = Push: Set
                                                                • .... .... .0.. = Reset: Not set
                                                                  • .... .... ..0. = Syn: Not set
                                                                    • .... .... ...0 = Fin: Not set
                                                                    • Window size value: 28800
                                                                      • Urgent pointer: 0
                                                                        • TCP payload (2 bytes)
                                                                        0000  04d2d1ccbca4e765  8626a14050107080  
                                                                        0010  00000000                            

                                                                        0000  .ÒÑ̼¤çe.&¡@P.p.
                                                                        0010  ....            
                                                                        • Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678592, Len: 0
                                                                          • Source Port: 1234
                                                                            • Destination Port: 53708
                                                                              • Sequence number: 3164923749
                                                                                • Acknowledgment number: 2250678592
                                                                                  • 0101 .... = Header Length: 20 bytes (5)
                                                                                    • Flags
                                                                                      • 000. .... .... = Reserved: Not set
                                                                                        • ...0 .... .... = Nonce: Not set
                                                                                          • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                            • .... .0.. .... = ECN-Echo: Not set
                                                                                              • .... ..0. .... = Urgent: Not set
                                                                                                • .... ...1 .... = Acknowledgment: Set
                                                                                                  • .... .... 0... = Push: Not set
                                                                                                    • .... .... .0.. = Reset: Not set
                                                                                                      • .... .... ..0. = Syn: Not set
                                                                                                        • .... .... ...0 = Fin: Not set
                                                                                                        • Window size value: 28800
                                                                                                          • Urgent pointer: 0
                                                                                                          0000  d1cc04d28626a13c  bca4e76550107080  
                                                                                                          0010  00000000                            

                                                                                                          0000  ÑÌ.Ò.&¡<¼¤çeP.p.
                                                                                                          0010  ....            
                                                                                                          • Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678588, Ack: 3164923749, Len: 0
                                                                                                            • Source Port: 53708
                                                                                                              • Destination Port: 1234
                                                                                                                • Sequence number: 2250678588
                                                                                                                  • Acknowledgment number: 3164923749
                                                                                                                    • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                      • Flags
                                                                                                                        • 000. .... .... = Reserved: Not set
                                                                                                                          • ...0 .... .... = Nonce: Not set
                                                                                                                            • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                              • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                • .... ..0. .... = Urgent: Not set
                                                                                                                                  • .... ...1 .... = Acknowledgment: Set
                                                                                                                                    • .... .... 0... = Push: Not set
                                                                                                                                      • .... .... .0.. = Reset: Not set
                                                                                                                                        • .... .... ..0. = Syn: Not set
                                                                                                                                          • .... .... ...0 = Fin: Not set
                                                                                                                                          • Window size value: 28800
                                                                                                                                            • Urgent pointer: 0
                                                                                                                                            0000  d1cc04d28626a13e  bca4e76550187080  
                                                                                                                                            0010  00000000320a                        

                                                                                                                                            0000  ÑÌ.Ò.&¡>¼¤çeP.p.
                                                                                                                                            0010  ....2.          
                                                                                                                                            • Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678590, Ack: 3164923749, Len: 2
                                                                                                                                              • Source Port: 53708
                                                                                                                                                • Destination Port: 1234
                                                                                                                                                  • Sequence number: 2250678590
                                                                                                                                                    • Acknowledgment number: 3164923749
                                                                                                                                                      • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                        • Flags
                                                                                                                                                          • 000. .... .... = Reserved: Not set
                                                                                                                                                            • ...0 .... .... = Nonce: Not set
                                                                                                                                                              • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                                                                • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                                                  • .... ..0. .... = Urgent: Not set
                                                                                                                                                                    • .... ...1 .... = Acknowledgment: Set
                                                                                                                                                                      • .... .... 1... = Push: Set
                                                                                                                                                                        • .... .... .0.. = Reset: Not set
                                                                                                                                                                          • .... .... ..0. = Syn: Not set
                                                                                                                                                                            • .... .... ...0 = Fin: Not set
                                                                                                                                                                            • Window size value: 28800
                                                                                                                                                                              • Urgent pointer: 0
                                                                                                                                                                                • TCP payload (2 bytes)
                                                                                                                                                                                0000  04d2d1ccbca4e765  8626a13e50107080  
                                                                                                                                                                                0010  00000000                            

                                                                                                                                                                                0000  .ÒÑ̼¤çe.&¡>P.p.
                                                                                                                                                                                0010  ....            
                                                                                                                                                                                • Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678590, Len: 0
                                                                                                                                                                                  • Source Port: 1234
                                                                                                                                                                                    • Destination Port: 53708
                                                                                                                                                                                      • Sequence number: 3164923749
                                                                                                                                                                                        • Acknowledgment number: 2250678590
                                                                                                                                                                                          • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                                                            • Flags
                                                                                                                                                                                              • 000. .... .... = Reserved: Not set
                                                                                                                                                                                                • ...0 .... .... = Nonce: Not set
                                                                                                                                                                                                  • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                                                                                                    • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                                                                                      • .... ..0. .... = Urgent: Not set
                                                                                                                                                                                                        • .... ...1 .... = Acknowledgment: Set
                                                                                                                                                                                                          • .... .... 0... = Push: Not set
                                                                                                                                                                                                            • .... .... .0.. = Reset: Not set
                                                                                                                                                                                                              • .... .... ..0. = Syn: Not set
                                                                                                                                                                                                                • .... .... ...0 = Fin: Not set
                                                                                                                                                                                                                • Window size value: 28800
                                                                                                                                                                                                                  • Urgent pointer: 0
                                                                                                                                                                                                                  0000  04d2d1ccbca4e765  8626a14450107080  
                                                                                                                                                                                                                  0010  00000000                            

                                                                                                                                                                                                                  0000  .ÒÑ̼¤çe.&¡DP.p.
                                                                                                                                                                                                                  0010  ....            
                                                                                                                                                                                                                  • Transmission Control Protocol, Src Port: 1234, Dst Port: 53708, Seq: 3164923749, Ack: 2250678596, Len: 0
                                                                                                                                                                                                                    • Source Port: 1234
                                                                                                                                                                                                                      • Destination Port: 53708
                                                                                                                                                                                                                        • Sequence number: 3164923749
                                                                                                                                                                                                                          • Acknowledgment number: 2250678596
                                                                                                                                                                                                                            • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                                                                                              • Flags
                                                                                                                                                                                                                                • 000. .... .... = Reserved: Not set
                                                                                                                                                                                                                                  • ...0 .... .... = Nonce: Not set
                                                                                                                                                                                                                                    • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                                                                                                                                      • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                                                                                                                        • .... ..0. .... = Urgent: Not set
                                                                                                                                                                                                                                          • .... ...1 .... = Acknowledgment: Set
                                                                                                                                                                                                                                            • .... .... 0... = Push: Not set
                                                                                                                                                                                                                                              • .... .... .0.. = Reset: Not set
                                                                                                                                                                                                                                                • .... .... ..0. = Syn: Not set
                                                                                                                                                                                                                                                  • .... .... ...0 = Fin: Not set
                                                                                                                                                                                                                                                  • Window size value: 28800
                                                                                                                                                                                                                                                    • Urgent pointer: 0
                                                                                                                                                                                                                                                    0000  d1cc04d28626a142  bca4e76550187080  
                                                                                                                                                                                                                                                    0010  00000000340a                        

                                                                                                                                                                                                                                                    0000  ÑÌ.Ò.&¡B¼¤çeP.p.
                                                                                                                                                                                                                                                    0010  ....4.          
                                                                                                                                                                                                                                                    • Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678594, Ack: 3164923749, Len: 2
                                                                                                                                                                                                                                                      • Source Port: 53708
                                                                                                                                                                                                                                                        • Destination Port: 1234
                                                                                                                                                                                                                                                          • Sequence number: 2250678594
                                                                                                                                                                                                                                                            • Acknowledgment number: 3164923749
                                                                                                                                                                                                                                                              • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                                                                                                                                • Flags
                                                                                                                                                                                                                                                                  • 000. .... .... = Reserved: Not set
                                                                                                                                                                                                                                                                    • ...0 .... .... = Nonce: Not set
                                                                                                                                                                                                                                                                      • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                                                                                                                                                                        • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                                                                                                                                                          • .... ..0. .... = Urgent: Not set
                                                                                                                                                                                                                                                                            • .... ...1 .... = Acknowledgment: Set
                                                                                                                                                                                                                                                                              • .... .... 1... = Push: Set
                                                                                                                                                                                                                                                                                • .... .... .0.. = Reset: Not set
                                                                                                                                                                                                                                                                                  • .... .... ..0. = Syn: Not set
                                                                                                                                                                                                                                                                                    • .... .... ...0 = Fin: Not set
                                                                                                                                                                                                                                                                                    • Window size value: 28800
                                                                                                                                                                                                                                                                                      • Urgent pointer: 0
                                                                                                                                                                                                                                                                                        • TCP payload (2 bytes)
                                                                                                                                                                                                                                                                                        0000  d1cc04d28626a13c  bca4e76550187080  
                                                                                                                                                                                                                                                                                        0010  00000000310a                        

                                                                                                                                                                                                                                                                                        0000  ÑÌ.Ò.&¡<¼¤çeP.p.
                                                                                                                                                                                                                                                                                        0010  ....1.          
                                                                                                                                                                                                                                                                                        • Transmission Control Protocol, Src Port: 53708, Dst Port: 1234, Seq: 2250678588, Ack: 3164923749, Len: 2
                                                                                                                                                                                                                                                                                          • Source Port: 53708
                                                                                                                                                                                                                                                                                            • Destination Port: 1234
                                                                                                                                                                                                                                                                                              • Sequence number: 2250678588
                                                                                                                                                                                                                                                                                                • Acknowledgment number: 3164923749
                                                                                                                                                                                                                                                                                                  • 0101 .... = Header Length: 20 bytes (5)
                                                                                                                                                                                                                                                                                                    • Flags
                                                                                                                                                                                                                                                                                                      • 000. .... .... = Reserved: Not set
                                                                                                                                                                                                                                                                                                        • ...0 .... .... = Nonce: Not set
                                                                                                                                                                                                                                                                                                          • .... 0... .... = Congestion Window Reduced (CWR): Not set
                                                                                                                                                                                                                                                                                                            • .... .0.. .... = ECN-Echo: Not set
                                                                                                                                                                                                                                                                                                              • .... ..0. .... = Urgent: Not set
                                                                                                                                                                                                                                                                                                                • .... ...1 .... = Acknowledgment: Set
                                                                                                                                                                                                                                                                                                                  • .... .... 1... = Push: Set
                                                                                                                                                                                                                                                                                                                    • .... .... .0.. = Reset: Not set
                                                                                                                                                                                                                                                                                                                      • .... .... ..0. = Syn: Not set
                                                                                                                                                                                                                                                                                                                        • .... .... ...0 = Fin: Not set
                                                                                                                                                                                                                                                                                                                        • Window size value: 28800
                                                                                                                                                                                                                                                                                                                          • Urgent pointer: 0
                                                                                                                                                                                                                                                                                                                            • TCP payload (2 bytes)