gentoo-overlay/net-libs/libpcap/metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE pkgmetadata SYSTEM "http://www.gentoo.org/dtd/metadata.dtd">
<pkgmetadata>
  <herd>netmon</herd>
  <use>
    <flag name='netlink'>
      Use <pkg>dev-libs/libnl</pkg> to put wireless interfaces in monitor mode.
    </flag>
    <flag name='canusb'>
      Use <pkg>virtual/libusb</pkg> to support Controller Area Network over USB (CAN USB)
    </flag>
  </use>
</pkgmetadata>