title: When linux send ack while hook on recv with ptrace
body: <p>I hook on syscall <code>recv</code> /<code>recvfrom</code> at that communication TCP with <code>ptrace</code> (PTRACE_SYSCALL) in linux Arm architecture and tried to modify the incoming data(modify data and size or incoming data)</p>
  <p>When the system send ACK to packet? Before I catch it with PRTACE_SYSCALL or after? If I modify the data that catched in those syscall is that problem because it is TCP communication?</p>