title: access and change the reserved bits on tcp header
body: <p>in rfc793, section-3.1, TCP header header have 6 reserved bits that decreased to 4 reserved bits on <a href="https://www.rfc-editor.org/rfc/rfc3168#section-6.1" rel="nofollow noreferrer">rfc3168</a>.
  How can i access and change these bits on Linux or with a program or even how can i write a program for this goal?</p>