Reordering the segments exchanged on a connection

A TCP connection, as explained in the TCP chapter of Computer Networking: Principles, Protocols and Practice starts with a three-way-handshake and ends with the exchange of segments with the FIN flag set.

Paste this command into your terminal:

The password to connect is

Reorder the entire connection

During this connection, the client opens a connection to the server that listens on port 1234. It then sends a single byte of data that was acknowledged by the server and then decided to terminate the connection. Can you reorder all the segments exchanged on this connection ?

#	Length	Summary
0	20 bytes	`Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899002, Ack: 2186540617, Len: 0`
1	20 bytes	`Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540617, Ack: 3405899002, Len: 0`
2	24 bytes	`Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899000, Len: 0`
3	20 bytes	`Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540617, Ack: 3405899003, Len: 0`
4	20 bytes	`Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899001, Ack: 2186540617, Len: 0`
5	20 bytes	`Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899003, Ack: 2186540618, Len: 0`
6	21 bytes	`Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899001, Ack: 2186540617, Len: 1`
7	24 bytes	`Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540616, Ack: 3405899001, Len: 0`

0000 d1d404d2cb01e4fa 8253f64950117080
0010 00000000

0000 ÑÔ.ÒË.äú.SöIP.p.
0010 ....

Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899002, Ack: 2186540617, Len: 0
- Source Port: 53716
- Destination Port: 1234
- Sequence number: 3405899002
- Acknowledgment number: 2186540617
- 0101 .... = Header Length: 20 bytes (5)
- Flags: 0x011 (FIN, 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
  - .... .... ..0. = Syn: Not set
  - .... .... ...1 = Fin: Set
- Window size value: 28800
- Urgent pointer: 0

0000 04d2d1d48253f649 cb01e4fa50107080
0010 00000000

0000 .ÒÑÔ.SöIË.äúP.p.
0010 ....

Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540617, Ack: 3405899002, Len: 0
- Source Port: 1234
- Destination Port: 53716
- Sequence number: 2186540617
- Acknowledgment number: 3405899002
- 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
  - .... .... ..0. = Syn: Not set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0

0000 d1d404d2cb01e4f8 0000000060027080
0010 00000000020405a0

0000 ÑÔ.ÒË.äø....`.p.
0010 ........

Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899000, Len: 0
- Source Port: 53716
- Destination Port: 1234
- Sequence number: 3405899000
- 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
  - .... .... ..1. = Syn: Set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0
- Options: (4 bytes), Maximum segment size
  - TCP Option - Maximum segment size: 1440 bytes
    - Kind: Maximum Segment Size (2)
    - Length: 4
    - MSS Value: 1440

0000 04d2d1d48253f649 cb01e4fb50117080
0010 00000000

0000 .ÒÑÔ.SöIË.äûP.p.
0010 ....

Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540617, Ack: 3405899003, Len: 0
- Source Port: 1234
- Destination Port: 53716
- Sequence number: 2186540617
- Acknowledgment number: 3405899003
- 0101 .... = Header Length: 20 bytes (5)
- Flags: 0x011 (FIN, 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
  - .... .... ..0. = Syn: Not set
  - .... .... ...1 = Fin: Set
- Window size value: 28800
- Urgent pointer: 0

0000 d1d404d2cb01e4f9 8253f64950107080
0010 00000000

0000 ÑÔ.ÒË.äù.SöIP.p.
0010 ....

Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899001, Ack: 2186540617, Len: 0
- Source Port: 53716
- Destination Port: 1234
- Sequence number: 3405899001
- Acknowledgment number: 2186540617
- 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
  - .... .... ..0. = Syn: Not set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0

0000 d1d404d2cb01e4fb 8253f64a50107080
0010 00000000

0000 ÑÔ.ÒË.äû.SöJP.p.
0010 ....

Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899003, Ack: 2186540618, Len: 0
- Source Port: 53716
- Destination Port: 1234
- Sequence number: 3405899003
- Acknowledgment number: 2186540618
- 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
  - .... .... ..0. = Syn: Not set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0

0000 d1d404d2cb01e4f9 8253f64950187080
0010 000000000a

0000 ÑÔ.ÒË.äù.SöIP.p.
0010 .....

Transmission Control Protocol, Src Port: 53716, Dst Port: 1234, Seq: 3405899001, Ack: 2186540617, Len: 1
- Source Port: 53716
- Destination Port: 1234
- Sequence number: 3405899001
- Acknowledgment number: 2186540617
- 0101 .... = Header Length: 20 bytes (5)
- Flags: 0x018 (PSH, 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
  - .... .... 1... = Push: Set
  - .... .... .0.. = Reset: Not set
  - .... .... ..0. = Syn: Not set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0
- TCP payload (1 byte)

0000 04d2d1d48253f648 cb01e4f960127080
0010 00000000020405a0

0000 .ÒÑÔ.SöHË.äù`.p.
0010 ........

Transmission Control Protocol, Src Port: 1234, Dst Port: 53716, Seq: 2186540616, Ack: 3405899001, Len: 0
- Source Port: 1234
- Destination Port: 53716
- Sequence number: 2186540616
- Acknowledgment number: 3405899001
- 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
  - .... .... ..1. = Syn: Set
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0
- Options: (4 bytes), Maximum segment size
  - TCP Option - Maximum segment size: 1440 bytes
    - Kind: Maximum Segment Size (2)
    - Length: 4
    - MSS Value: 1440

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

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