Using pcaps from https://interop.seemann.io/ as samples for QUIC protocol
data didn't produce a conn.log for the contained data. `tcpdump -r`
and Wireshark do show the contained IP/UDP packets. Teach Zeek how
to handle link type DLT_PPP 0x09 using a new PPP analyzer based on the
PPPSerial analyzer code.
Usual update to files/x509 baseline after adding new analyzer due
to enum values changing.
