TCP simultaneous establishment

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TCP simultaneous connection establishment

Under specific circumstances, two TCP hosts can send a SYN segment at the same time. In this case, the establishment of a connection requires the transmission of four segments. Can you fill the missing fields of these four segments ?

#	Length	Summary
0	24 bytes	`Transmission Control Protocol, Src Port: 43494, Dst Port: 8080, Seq: 4224100836, Len: 0`
1	24 bytes	`Transmission Control Protocol, Src Port: 8080, Dst Port: 43494, Seq: 0, Len: 0`
2	24 bytes	`Transmission Control Protocol, Src Port: 43494, Dst Port: 8080, Seq: 4224100836, Ack: ????, Len: 0`
3	20 bytes	`Transmission Control Protocol, Src Port: 8080, Dst Port: 43494, Seq: 1, Ack: ????, Len: 0`

0000 a9e61f90fbc6a9e4 0000000060??4e20
0010 021c0000020403e8

0000 ©æ..ûÆ©ä....`?N
0010 .......è

Transmission Control Protocol, Src Port: 43494, Dst Port: 8080, Seq: 4224100836, Len: 0
- Source Port: 43494
- Destination Port: 8080
- TCP Segment Len: 0
- Sequence number: 4224100836
- Acknowledgment number: 0
- 0110 .... = Header Length: 24 bytes (6)
- Flags: 0x002 (SYN)
  - 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
  - .... .... ..?. = Syn: ?
  - .... .... ...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 1f90a9e600000000 0000000060??16a0
0010 b7de0000020403e8

0000 ..©æ........`?..
0010 ·Þ.....è

Transmission Control Protocol, Src Port: 8080, Dst Port: 43494, Seq: 0, Len: 0
- Source Port: 8080
- Destination Port: 43494
- TCP Segment Len: 0
- Sequence number: 0
- Acknowledgment number: 0
- 0110 .... = Header Length: 24 bytes (6)
- Flags: 0x002 (SYN)
  - 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
  - .... .... ..?. = Syn: ?
  - .... .... ...0 = Fin: Not set
- Window size value: 5792
- Calculated window size: 5792
- Checksum: 0xb7de [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 a9e61f90fbc6a9e4 ????????60??4e20
0010 021c0000020403e8

Transmission Control Protocol, Src Port: 43494, Dst Port: 8080, Seq: 4224100836, Ack: ????, Len: 0
- Source Port: 43494
- Destination Port: 8080
- TCP Segment Len: 0
- Sequence number: 4224100836
- Acknowledgment number: ?
- 0110 .... = Header Length: 24 bytes (6)
- Flags: 0x012 (SYN, ACK)
  - 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
  - .... .... ..?. = Syn: ?
  - .... .... ...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 1f90a9e600000001 ????????50??16a0
0010 28130000

Transmission Control Protocol, Src Port: 8080, Dst Port: 43494, Seq: 1, Ack: ????, Len: 0
- Source Port: 8080
- Destination Port: 43494
- TCP Segment Len: 0
- Sequence number: 1
- Acknowledgment number: ?
- 0101 .... = Header Length: 20 bytes (5)
- Flags: 0x010 (ACK)
  - 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
  - .... .... ..?. = Syn: ?
  - .... .... ...0 = Fin: Not set
- Window size value: 5792
- Calculated window size: 5792
- Window size scaling factor: -2 (no window scaling used)
- Checksum: 0x2813 [unverified]
- Urgent pointer: 0

Author(s)	Olivier Bonaventure
Deadline	Keine Frist
Abgabenlimit	No limitation
Category tags	tcp

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