title: modify captured pcap and write back
body: <p>I need to read captured pcap file, that contains some proprietary descriptor appended by FPGA at the start of file right after MAC header, add extra 2 bytes to the descriptor and write back.</p>
  
  <p>I'm trying to implement this in C using libpcap library on linux. Am I right that I will need to call pcap_dump_open() and pcap_dump() to write buffer? Also, is is true that I'll need to increment caplen and and 'len' from pcap_pkthdr accordingly (add 2) prior writing the buffer with pcap_dump?</p>
  
  <p>Thanks in advance !</p>