title: Hardware timestamping PCAP
body: <p>I'm building a c++ latency measurement library, with the intention on getting as close to a network-only latency measurement.  Hardware timestamping seems to be the way to go.</p>
  
  <p>I'm using a sniffer to detect packets sent over TCP.  My question is, to get the soonest timestamp possible, which should I be using - kernel's <code>SOF_TIMESTAMPING_RX_HARDWARE</code> or libpcap's <code>PCAP_TSTAMP_ADAPTER</code>?</p>
  
  <p>What is the difference?  My guess is they both return the same values, since they are seeking the timestamp at the NIC, logically meaning it doesn't matter which is used.  Is this the case?</p>