ICMP codes

0 echo reply
3 dest unreachable
4 source quench
5 redirect
8 echo request
9 router advertisements
10 router solicitations
11 time exceeded
12 parameter problem
13 timestamp request
14 timestamp reply
15 information request
16 information reply
17 address mask
18 address mask reply

Type 0/8 - Echo or Echo Reply Message (PING)
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The data received in the echo message must be returned in the echo reply message.

Type 3 - Destination Unreachable Message
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Code
0 = net unreachable;
1 = host unreachable;
2 = protocol unreachable;
3 = port unreachable;
4 = fragmentation needed and DF set.

Type 5 - Redirect Message
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Code
0 = Redirect datagrams for the Network.
1 = Redirect datagrams for the Host.
2 = Redirect datagrams for the Type of Service and Network.
3 = Redirect datagrams for the Type of Service and Host.

Type 11 - Time Exceeded Message
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Code
0 = time to live exceeded in transit;
1 = fragment reassembly time exceeded.

Type 12 - Parameter Problem Message
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Code
0 = problem with option.

Type 13/14 - Timestamp or Timestamp Reply Message
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The data received (a timestamp) in the message is returned in the reply together with an additional timestamp.