The TCP sequence numbers used during the data transfer

The TCP header, shown in the TCP chapter of Computer Networking: Principles, Protocols and Practice contains a sequence number. The segments below correspond to the beginning of a TCP connection.


Sequence numbers

Can you infer the sequence numbers of the two segments that transfer data in the trace below ?

# Length Resumé Status
0 24 bytes <TCP: SYN, SEQ: 925123579, ACK: 0, MSS>
1 24 bytes <TCP: ACK, SYN, SEQ: 3658695655, ACK: 925123580, MSS>
2 20 bytes <TCP: ACK, SEQ: 925123580, ACK: 3658695656>
3 20 bytes <TCP: ACK, PSH, SEQ: ??, ACK: 3658695656>  
4 20 bytes <TCP: ACK, SEQ: 3658695656, ACK: 925123582>
5 20 bytes <TCP: ACK, PSH, SEQ: ??, ACK: 3658695656>  
6 20 bytes <TCP: ACK, SEQ: 3658695656, ACK: 925123585>

0000  d1ca04d2372443fb  0000000060027080  
0010  4f900000020405a0                    

0000  ÑÊ.Ò7$Cû....`.p.
0010  O.......        
  • TCP:
    • Source Port: 53706
    • Destination Port: 1234
    • Sequence Number: 925123579
    • Acknowledgment Number: 0
    • Data Offset: 6
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 0
    • PSH: 0
    • RST: 0
    • SYN: 1
    • FIN: 0
    • Window: 28800
    • Checksum: 20368
    • Urgent Pointer: 0
    • Options: Maximum Segment Size
      • Kind: 2
      • Length: 4
      • Max Seg Size: 1440
0000  04d2d1cada1343e7  372443fc60127080  
0010  4f900000020405a0                    

0000  .ÒÑÊÚ.Cç7$Cü`.p.
0010  O.......        
  • TCP:
    • Source Port: 1234
    • Destination Port: 53706
    • Sequence Number: 3658695655
    • Acknowledgment Number: 925123580
    • Data Offset: 6
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 0
    • RST: 0
    • SYN: 1
    • FIN: 0
    • Window: 28800
    • Checksum: 20368
    • Urgent Pointer: 0
    • Options: Maximum Segment Size
      • Kind: 2
      • Length: 4
      • Max Seg Size: 1440
0000  d1ca04d2372443fc  da1343e850107080  
0010  4f8c0000                            

0000  ÑÊ.Ò7$CüÚ.CèP.p.
0010  O...            
  • TCP:
    • Source Port: 53706
    • Destination Port: 1234
    • Sequence Number: 925123580
    • Acknowledgment Number: 3658695656
    • Data Offset: 5
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 0
    • RST: 0
    • SYN: 0
    • FIN: 0
    • Window: 28800
    • Checksum: 20364
    • Urgent Pointer: 0
0000  d1ca04d2????????  da1343e850187080  
0010  4f8e0000                            

0000  ÑÊ.Ò????Ú.CèP.p.
0010  O...            
  • TCP:
    • Source Port: 53706
    • Destination Port: 1234
    • Sequence Number:
    • Acknowledgment Number: 3658695656
    • Data Offset: 5
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 1
    • RST: 0
    • SYN: 0
    • FIN: 0
    • Window: 28800
    • Checksum: 20366
    • Urgent Pointer: 0
0000  04d2d1cada1343e8  372443fe50107080  
0010  4f8c0000                            

0000  .ÒÑÊÚ.Cè7$CþP.p.
0010  O...            
  • TCP:
    • Source Port: 1234
    • Destination Port: 53706
    • Sequence Number: 3658695656
    • Acknowledgment Number: 925123582
    • Data Offset: 5
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 0
    • RST: 0
    • SYN: 0
    • FIN: 0
    • Window: 28800
    • Checksum: 20364
    • Urgent Pointer: 0
0000  d1ca04d2????????  da1343e850187080  
0010  4f8f0000                            

0000  ÑÊ.Ò????Ú.CèP.p.
0010  O...            
  • TCP:
    • Source Port: 53706
    • Destination Port: 1234
    • Sequence Number:
    • Acknowledgment Number: 3658695656
    • Data Offset: 5
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 1
    • RST: 0
    • SYN: 0
    • FIN: 0
    • Window: 28800
    • Checksum: 20367
    • Urgent Pointer: 0
0000  04d2d1cada1343e8  3724440150107080  
0010  4f8c0000                            

0000  .ÒÑÊÚ.Cè7$D.P.p.
0010  O...            
  • TCP:
    • Source Port: 1234
    • Destination Port: 53706
    • Sequence Number: 3658695656
    • Acknowledgment Number: 925123585
    • Data Offset: 5
    • Reserved: 0
    • NS: 0
    • CWR: 0
    • ECE: 0
    • URG: 0
    • ACK: 1
    • PSH: 0
    • RST: 0
    • SYN: 0
    • FIN: 0
    • Window: 28800
    • Checksum: 20364
    • Urgent Pointer: 0

Information

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

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