A collection of packet captures and notes on how to analyze them.
https://wiki.wireshark.org/SampleCaptures#protobuf
https://wiki.wireshark.org/SampleCaptures#ipv6-and-tunneling-mechanism
https://wiki.wireshark.org/SampleCaptures#ssl-with-decryption-keys
https://wiki.wireshark.org/SampleCaptures#kerberos-and-keytab-file-for-decryption
https://wiki.wireshark.org/SampleCaptures#x-509-digital-certificates
https://packetlife.net/captures/
https://www.netresec.com/?page=PcapFiles