ICMP Echo Request
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The Echo Request is an ICMP message which sends a packet of data to the host and expects that data to be sent in return in an Echo Reply. The host must respond to all Echo Requests with an Echo Reply containing the exact data received in the request message.
Message Format:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type = 8 | Code = 0 | Header Checksum | |||||||||||||||||||||||||||||
| Identifier | Sequence Number | ||||||||||||||||||||||||||||||
| Data ::: | |||||||||||||||||||||||||||||||
- Type must be set to 8.
- Code must be set to 0.
- The Identifier and Sequence Number can be used by the client to match the reply with the request that caused the reply.
- The data received by the Echo Request must be entirely included in the Echo Reply.
