## Dump everything in the capture file.
tcpdump -r all-http-traffic-tun0.pcap

## This will show the same thing, since this expression was already used to
## filter the same thing at capture time.
tcpdump -r all-http-traffic-tun0.pcap "dst port 80"

## This shows traffic to an HTTP service on example.com; it'll still only show
## destination port 80 because that's all that's in the capture file in the
## first place.
tcpdump -r all-http-traffic-tun0.pcap "dst host example.com"