Commonly used ICMP types and codes:
- 0, 0 - echo reply
- 8, 0 - echo request
- 3, 0 - dest. unreachable: network
- 3, 1 - dest. unreachable: host
- 3, 2 - dest. unreachable: protocol
- 3, 3 - dest. unreachable: port
- 3, 4 - dest. unreachable: frag needed and DF was set
- 13, 0 - timestamp request
- 14, 0 - timestamp reply
- 15, 0 - info request
- 16, 0 - info reply
- 17, 0 - mask request
- 18, 0 - mask reply