INTERNET CONTROL MESSAGE PROTOCOL

April 3, 2017 0 comments Article Networking Kumaradev

ICMP is a networking protocol developed to analyse the connectivity between source and destination hosts.

The structure of ICMP datagram as follows

Data (32 bytes by default)
Sequence No: – Since it is sending data repeatedly, ICMP itself assings a sequence number to identify the segment of data
Identifier – It is very close to port number. An identifier is assinged on each echo packets from the begining till the end of all sequence of data
Checksum – Used for error detection
Packet Type – To identify what type of ICMP packet
Code – There are different codes for each type of ICMP packet.

The following content will gives you clearity about different Packet Types and what are the different codes for each Packet Types

Type	Code /Name
0	Echo Reply
3	Destination Unreachable
	0 Network Unreachable
	1 Host Unreachable
	2 Protocol Unreachable
	3 Port Unreachable
	4 Fragmentaiton required, and DF set
	5 Source Rooute Failed
	6 Destionation Network Unknown
	7 Destination Host Unknown
	8 Source Host Isolated
	9 Network Administratively Prohibited
	10 Host Administratively Prohibited
	11 Network Unreachable for TOS
	12 Host Unreacheable for TOS
	13 Communication Administratively Prohibited
4	Source Quench
5	Redirect
	0 Redirect Datagram for the Network
	1 Redirect Datagram for the Host
	2 Redirect datargram for the TOS & Network
	3 Redirect Datagram for the TOS & Host
8	Echo
9	Router Advertisement
10	Router Selection
11	Time Exceeded
	0 TTL Exceeded
	1 Fragment Reassembly Time Exceeded
12	Parameter Problem
	0 Pointer Problem
	1 Missing a Required Operand
	2 Bad Length
13	Timestamp
14	Timestamp Reply
15	Information Request
16	Information Reply
17	Address Mask Request
18	Address Mask Reply
30	Traceroute

Type