Using Tcpdump to analyze HTTP won't always work. Unless I'm mistaken, Tcpdump doesn't decode packet fragments into a stream, so if the request is fragmented, yo

Using Tcpdump to analyze HTTP won't always work. Unless I'm mistaken, Tcpdump doesn't decode packet fragments into a stream, so if the request is fragmented, your grep won't work. If there are multiple HTTP requests in one TCP stream, it's less likely they are aligned completely in one packet, also fragmenting the request. And if it's a request to Google it could be in QUIC rather than TCP. You may wonder what on your network is broken because you can't see the requests, but it's just the network fragmenting packets. Tshark (nee Wireshark) I believe does decode packet fragments into streams, and allows you to use more advanced Wireshark protocol filters. My suggestion is to start a pcap capture, and at the same time replay it using Tshark with the filters you want. This way you can re-analyze the same live traffic both now and later.