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I was trying to send ICMP package with Payload/Message on server_A to server_B(10.1.1.5) as following: ping -p 12345 10.1.1.5.

but when I use Tcpdump to capture the ICMP package from server_A, I didn't see any message(it should be 12345). How can I get the icmp payload please?

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  • Different implementations of the ping application can do things differently.
    – Ron Maupin ♦
    Commented Mar 30, 2019 at 1:26

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Ping doesn't send user messages. It generates an ICMP Echo Request that the destination is supposed to answer with an ICMP Echo Reply.

Echo requests use a dummy payload data encapsulated within the packet. -p allows you to specify hte content of that payload with some ping versions. -p 12345 fills the payload with 0x012345 bytes repetitively for the specified length (-s parameter for Linux). The echo reply returns the dummy payload if working correctly.

For details, see RFC 792 page 14.

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