Follow up for PacketCapture feature.

[hangyan]

Possible future improvements in the future:

• bi-direction capture This was marked as a future improvement during the design stage. We could add a bool field in the spec to turn this on.

• ipv6 currently the ipFamily field in spec has a fixed value ipv4.

• tcp flags filter

• icmp echo/reply filter add new section in transportHeader struct to support icmp filters.

• antctl support download the pcap file directly from cli

• capture both on source/target users maybe want to check the diff.

Current issues:

1. captured file cannot be opened by tcpdump on mac, works on linux. ( Wireshark is fine on mac) (#6804)

reading from PCAP-NG file pc-test-tcp.pcapng. tcpdump: pcap_loop: invalid packet capture length 74, bigger than snaplen of 524288

this is the error message shown when reading packets from tcpdump on mac. It works fine with linux and WIreshark(mac).

2. https://github.com/antrea-io/antrea/issues/6815

Related to:

1. https://github.com/antrea-io/antrea/pull/6756
2. https://github.com/antrea-io/antrea/issues/5443

[hangyan]

cc @luolanzone