ICMP Header

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Type :

0 : Echo Reply

3 : Destination Unreachable

5 : Redirect

........

8 : Echo Request

11 : Time Exceeded

Code (Type 3):

0 : Net Unreachable

1 : Host Unreachable

2 : protocol Unreachable

3 : Port Unreachable

5 : Source Route Failed

6 : Destination Network Unknown

7 : Destination Host Unknown

Code (Type 5):

0 : Redirect Datagram for Network

1 : Redirect Datagram for Host

2 : Redirect Datagram for TOS & Network

3 : Redirect Datagram for TOS & Host