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Forum Replies

  1. Hello Prathamesh!

    The TCP sequence number is random because, as Rene mentioned earlier, TCP is vulnerable to security issues like spoofing, injection or connection resetting. If an a attacker is able to determine the sequence number, he/she would be able to spoof a trusted source, and thus compromise the TCP session.

    For an example of such a spoofing attack, take a look at the following link: http://www.citi.umich.edu/u/provos/papers/secnet-spoof.txt

    (Notice that this paper is almost 20 years old and yet it’s still valid today!!! Shows just how well designed

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  2. Hello Rayniero.

    A TCP checksum is used to determine if a TCP segment has been transmitted successfully and without corruption. The sender of the segment computes a checksum by applying an algorithm to the payload and getting a result. The result is placed in the TCP checksum field. When the segment reaches the receiver, the checksum is recomputed with the same algorithm and compared to the checksum sent by the sender. If a bit is flipped or some other badness happens to the segment in transit, then it is highly likely that the receiver of that broken packet

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  3. Hi Rene ,
    Thanks for explaining networking so nicely . I have a question here . Why TCP needs 3 way handshake why 2 way is not enough

  4. i have another question please.
    It only adds 1 when handshaking, but not during data transfer?

  5. Hello Samuel.

    Concerning your questions about sequence numbers:

    I want to know if the last sequence number of the three way handshake is the same after the hanshake?

    The quick answer is yes. Now for more detail. When a TCP session begins, a sequence number is chosen to begin the handshake. This very first sequence number is random. (However, if you look at the sequence numbers portrayed in Wireshark, you’ll see that it starts at 1. This is the RELATIVE sequence number, as it states in Wireshark. It is displayed in this way for simplicity.) Once the hands

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