The source and destination ports in the TCP headers

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


TCP source and destination ports

The first TCP segment was sent by a client to a server to establish a connection. From the response returned by the server, can you infer the source and destination ports used in the first segment ?

# Length Resumé Status
0 24 bytes <TCP: SYN, SEQ: 3378592492, ACK: 0, MSS>  
1 24 bytes <TCP: ACK, SYN, SEQ: 2477434131, ACK: 3378592493, MSS>

0000  ????????c9613aec  0000000060027080  
0010  4f900000020405a0                    

0000  ????Éa:ì....`.p.
0010  O.......        
  • TCP:
    • Source Port:
    • Destination Port:
    • Sequence Number: 3378592492
    • 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  04d2d1ce93aaa513  c9613aed60127080  
0010  4f900000020405a0                    

0000  .ÒÑÎ.ª¥.Éa:í`.p.
0010  O.......        
  • TCP:
    • Source Port: 1234
    • Destination Port: 53710
    • Sequence Number: 2477434131
    • Acknowledgment Number: 3378592493
    • 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

Information

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

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