title: Wireshark: Flag abbreviations and Exchange type
body: <p>I was told to ask this here:</p>
  
  <p>10:53:04.042608 IP 172.17.2.12.42654 > 172.17.2.6.6000: Flags [FPU], seq 3891587770, win 1024, urg 0, length 0</p>
  
  <p>10:53:04.045939 IP 172.17.2.6.6000 > 172.17.2.12.42654: Flags [R.], seq 0, ack 3891587770, win 0, length 0</p>
  
  <p>This states that the flags set are FPU and R. What flags do these stand for and what kind of exchange is this?</p>