Reordering the three-way-handshake and infering the TCP flags - [CNP3] Computer Networking : Principles, Protocols and Practice | INGInious

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

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Reordering the three-way-handshake and infering the TCP flags

A TCP connection, as explained in the TCP chapter of Computer Networking: Principles, Protocols and Practice always starts with a three-way-handshake.

Paste this command into your terminal:

The password to connect is

Reorder the three-way-handshake and infer the TCP flags

Can you correctly reorder the three segments that are used to establish a TCP connection and set the SYN and ACK flags correctly ?

#	Length	Summary	Status
0	24 bytes	`Transmission Control Protocol, Src Port: 1234, Dst Port: 53720, Seq: 1554975569, Ack: 1541628760, Len: 0`
1	20 bytes	`Transmission Control Protocol, Src Port: 53720, Dst Port: 1234, Seq: 1541628760, Ack: 1554975570, Len: 0`
2	24 bytes	`Transmission Control Protocol, Src Port: 53720, Dst Port: 1234, Seq: 1541628759, Len: 0`

0000 04d2d1d85caf0b51 5be3635860??7080
0010 00000000020405a0

0000 .ÒÑØ\¯.Q[ãcX`?p.
0010 ........

Transmission Control Protocol, Src Port: 1234, Dst Port: 53720, Seq: 1554975569, Ack: 1541628760, Len: 0
- Source Port: 1234
- Destination Port: 53720
- Sequence number: 1554975569
- Acknowledgment number: 1541628760
- 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
  - .... ...? .... = Acknowledgment: ?
  - .... .... 0... = Push: Not set
  - .... .... .0.. = Reset: Not set
  - .... .... ..?. = Syn: ?
  - .... .... ...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 d1d804d25be36358 5caf0b5250??7080
0010 00000000

0000 ÑØ.Ò[ãcX\¯.RP?p.
0010 ....

Transmission Control Protocol, Src Port: 53720, Dst Port: 1234, Seq: 1541628760, Ack: 1554975570, Len: 0
- Source Port: 53720
- Destination Port: 1234
- Sequence number: 1541628760
- Acknowledgment number: 1554975570
- 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
  - .... ...? .... = Acknowledgment: ?
  - .... .... 0... = Push: Not set
  - .... .... .0.. = Reset: Not set
  - .... .... ..?. = Syn: ?
  - .... .... ...0 = Fin: Not set
- Window size value: 28800
- Urgent pointer: 0

0000 d1d804d25be36357 0000000060??7080
0010 00000000020405a0

0000 ÑØ.Ò[ãcW....`?p.
0010 ........

Transmission Control Protocol, Src Port: 53720, Dst Port: 1234, Seq: 1541628759, Len: 0
- Source Port: 53720
- Destination Port: 1234
- Sequence number: 1541628759
- 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
  - .... ...? .... = Acknowledgment: ?
  - .... .... 0... = Push: Not set
  - .... .... .0.. = Reset: Not set
  - .... .... ..?. = Syn: ?
  - .... .... ...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