Ping tool ICMP message learning

First , Here is a good blog ：
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Let's make a conclusion first ,Ping It's through IP+ICMP The agreement was sent , This is our tradition UDP and TCP Dissimilarity , It creates sockets directly from IP Layer accepts data , For details, please refer to the above documents .

Why? ICMP Of ping and tracert Not pass tcp or udp?

Another is sending UDP after , If the other port does not exist , Then the other server will return a ICMP message , This is shown below ：

About how to make UDP Get whether the opposite port exists , You can read this blog ：
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