Dump/tap is an area that we haven't gone into yet in Envoy but potentially has a huge amount of value. Opening this issue to gather a feature set that would be generally interesting. Some things to think about:

• L4 and L7 dumping
• Dumping to file
• Dumping to network
• Controlling dumping via filters (like tcpdump)
• Controlling dumping via admin endpoint
• Controlling dumping via new xDS API (for system-wide dumping w/ filters)

What else?