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

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Another TCP connection release


Connection release

In this trace, the local host issued close immediately after having accepted the connection. Can you fill the missing information in the last four TCP segments ?

# Length Summary Status
0 24 bytes Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: 2520729040, Len: 0
1 24 bytes Transmission Control Protocol, Src Port: 8080, Dst Port: 43508, Seq: 0, Ack: 2520729041, Len: 0
2 20 bytes Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: 2520729041, Ack: 1, Len: 0
3 20 bytes Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: ????, Ack: ????, Len: 0  
4 20 bytes Transmission Control Protocol, Src Port: 8080, Dst Port: 43508, Seq: ????, Ack: ????, Len: 0  
5 20 bytes Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: ????, Ack: ????, Len: 0  

0000  a9f41f90963f45d0  0000000060024e20  
0010  021c0000020403e8                    

0000  ©ô...?EÐ....`.N
0010  .......è        
  • Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: 2520729040, Len: 0
    • Source Port: 43508
      • Destination Port: 8080
        • TCP Segment Len: 0
          • Sequence number: 2520729040
            • Acknowledgment number: 0
              • 0110 .... = Header Length: 24 bytes (6)
                • 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
                            • .... ...0 .... = Acknowledgment: Not set
                              • .... .... 0... = Push: Not set
                                • .... .... .0.. = Reset: Not set
                                  • .... .... ..1. = Syn: Set
                                    • .... .... ...0 = Fin: Not set
                                    • Window size value: 20000
                                      • Calculated window size: 20000
                                        • Checksum: 0x021c [unverified]
                                          • Urgent pointer: 0
                                            • Options: (4 bytes), Maximum segment size
                                              • TCP Option - Maximum segment size: 1000 bytes
                                                • Kind: Maximum Segment Size (2)
                                                  • Length: 4
                                                    • MSS Value: 1000
                                                0000  1f90a9f400000000  963f45d160122710  
                                                0010  cb3f0000020403e8                    

                                                0000  ..©ô.....?EÑ`.'.
                                                0010  Ë?.....è        
                                                • Transmission Control Protocol, Src Port: 8080, Dst Port: 43508, Seq: 0, Ack: 2520729041, Len: 0
                                                  • Source Port: 8080
                                                    • Destination Port: 43508
                                                      • TCP Segment Len: 0
                                                        • Sequence number: 0
                                                          • Acknowledgment number: 2520729041
                                                            • 0110 .... = Header Length: 24 bytes (6)
                                                              • 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
                                                                                • .... .... ..1. = Syn: Set
                                                                                  • .... .... ...0 = Fin: Not set
                                                                                  • Window size value: 10000
                                                                                    • Calculated window size: 10000
                                                                                      • Checksum: 0xcb3f [unverified]
                                                                                        • Urgent pointer: 0
                                                                                          • Options: (4 bytes), Maximum segment size
                                                                                            • TCP Option - Maximum segment size: 1000 bytes
                                                                                              • Kind: Maximum Segment Size (2)
                                                                                                • Length: 4
                                                                                                  • MSS Value: 1000
                                                                                              0000  a9f41f90963f45d1  0000000150104e20  
                                                                                              0010  02180000                            

                                                                                              0000  ©ô...?EÑ....P.N
                                                                                              0010  ....            
                                                                                              • Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: 2520729041, Ack: 1, Len: 0
                                                                                                • Source Port: 43508
                                                                                                  • Destination Port: 8080
                                                                                                    • TCP Segment Len: 0
                                                                                                      • Sequence number: 2520729041
                                                                                                        • Acknowledgment number: 1
                                                                                                          • 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: 20000
                                                                                                                                  • Calculated window size: 20000
                                                                                                                                    • Window size scaling factor: -2 (no window scaling used)
                                                                                                                                      • Checksum: 0x0218 [unverified]
                                                                                                                                        • Urgent pointer: 0
                                                                                                                                        0000  a9f41f90????????  ????????50114e20  
                                                                                                                                        0010  02180000                            

                                                                                                                                        0000  ©ô..????????P.N
                                                                                                                                        0010  ....            
                                                                                                                                        • Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: ????, Ack: ????, Len: 0
                                                                                                                                          • Source Port: 43508
                                                                                                                                            • Destination Port: 8080
                                                                                                                                              • TCP Segment Len: 0
                                                                                                                                                • Sequence number: ?
                                                                                                                                                • Acknowledgment number: ?
                                                                                                                                                • 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
                                                                                                                                                                      • .... .... ...1 = Fin: Set
                                                                                                                                                                      • Window size value: 20000
                                                                                                                                                                        • Calculated window size: 20000
                                                                                                                                                                          • Window size scaling factor: -2 (no window scaling used)
                                                                                                                                                                            • Checksum: 0x0218 [unverified]
                                                                                                                                                                              • Urgent pointer: 0
                                                                                                                                                                              0000  1f90a9f4????????  ????????50112710  
                                                                                                                                                                              0010  e12e0000                            

                                                                                                                                                                              0000  ..©ô????????P.'.
                                                                                                                                                                              0010  á...            
                                                                                                                                                                              • Transmission Control Protocol, Src Port: 8080, Dst Port: 43508, Seq: ????, Ack: ????, Len: 0
                                                                                                                                                                                • Source Port: 8080
                                                                                                                                                                                  • Destination Port: 43508
                                                                                                                                                                                    • TCP Segment Len: 0
                                                                                                                                                                                      • Sequence number: ?
                                                                                                                                                                                      • Acknowledgment number: ?
                                                                                                                                                                                      • 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
                                                                                                                                                                                                            • .... .... ...1 = Fin: Set
                                                                                                                                                                                                            • Window size value: 10000
                                                                                                                                                                                                              • Calculated window size: 10000
                                                                                                                                                                                                                • Window size scaling factor: -2 (no window scaling used)
                                                                                                                                                                                                                  • Checksum: 0xe12e [unverified]
                                                                                                                                                                                                                    • Urgent pointer: 0
                                                                                                                                                                                                                    0000  a9f41f90????????  ????????50104e20  
                                                                                                                                                                                                                    0010  02180000                            

                                                                                                                                                                                                                    0000  ©ô..????????P.N
                                                                                                                                                                                                                    0010  ....            
                                                                                                                                                                                                                    • Transmission Control Protocol, Src Port: 43508, Dst Port: 8080, Seq: ????, Ack: ????, Len: 0
                                                                                                                                                                                                                      • Source Port: 43508
                                                                                                                                                                                                                        • Destination Port: 8080
                                                                                                                                                                                                                          • TCP Segment Len: 0
                                                                                                                                                                                                                            • Sequence number: ?
                                                                                                                                                                                                                            • Acknowledgment number: ?
                                                                                                                                                                                                                            • 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: 20000
                                                                                                                                                                                                                                                    • Calculated window size: 20000
                                                                                                                                                                                                                                                      • Window size scaling factor: -2 (no window scaling used)
                                                                                                                                                                                                                                                        • Checksum: 0x0218 [unverified]
                                                                                                                                                                                                                                                          • Urgent pointer: 0