Whenever, we do a wireshark capture and Follow--> TCP Stream, we see the sequence numbers as fixed values.

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In reality, if this were the case, the intruder can easily predict the transmission patterns.How is it actually, avoided to ensure a secure communication ?

  • 3
    For secure communication, SSL/TLS is required.
    – Zac67
    Jun 22 '19 at 12:49
  • 1
    TCP does not provide secure communication. That must be handled by something else.
    – Ron Maupin
    Jun 22 '19 at 14:07
  • 1
    Note that Wireshark shows relative TCP sequence numbers by default. You can disable that behavior in the TCP protocol preferences. Jun 28 '19 at 23:24

This is known as a TCP sequence prediction attack. There is a RFC defined to defend against it, RFC6528

In a nutshell, some vendors are responding to the threat by introducing random sequence number generation however overall participation is fairly low.

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