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Handbook

ICMP types and codes

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ICMP types and codes

ICMP has a number of messages that are identified by the “Type” field. Some of these types have assigned “Code” fields as well. The table below shows the different types of ICMP Types with their associated codes if there are any.

ICMP types and codes
Type Number Type Name Optional Code(s)
0 Echo Reply
1 Unassigned
2 Unassigned
3 Destination Unreachable 0 Net Unreachable

1 Host Unreachable

2 Protocol Unreachable

3 Port Unreachable

4 Fragmentation Needed and Don't Fragment was Set

5 Source Route Failed

6 Destination Network Unknown

7 Destination Host Unknown

8 Source Host Isolated

9 Communication with Destination Network is Administratively Prohibited

10 Communication with Destination Host is Administratively Prohibited

11 Destination Network Unreachable for Type of Service

12 Destination Host Unreachable for Type of Service

13 Communication Administratively Prohibited

14 Host Precedence Violation

15 Precedence cutoff in effect
4 Source Quench
5 Redirect 0 Redirect Datagram for the Network (or subnet)

1 Redirect Datagram for the Host

2 Redirect Datagram for the Type of Service and Network

3 Redirect Datagram for the Type of Service and Host
6 Alternate Host Address
7 Unassigned
8 Echo
9 Router Advertisement
10 Router Selection
11 Time Exceeded 0 Time to Live exceeded in Transit

1 Fragment Reassembly Time Exceeded
12 Parameter Problem 0 Pointer indicates the error

1 Missing a Required Option

2 Bad Length
13 Timestamp
14 Timestand Reply
15 Information Request
16 Information Reply
17 Address Mask Request
18 Address Mask Reply
19 Reserved (for Security)
20 - 29 Reserved (for Robustness Experiment)
30 Traceroute
31 Datagram Conversion Error
32 Mobile Host Redirect
33 IPv6 Where-Are-You
34 IPv6 I-Am-Here
35 Mobile Registration
36 Mobile Registration Reply
37 Domain Name Request
38 Domain Name Reply
39 SKIP
40 Photuris
41 - 255 Reserved

ICMP types and codes

ICMP has a number of messages that are identified by the “Type” field. Some of these types have assigned “Code” fields as well. The table below shows the different types of ICMP Types with their associated codes if there are any.

ICMP types and codes
Type Number Type Name Optional Code(s)
0 Echo Reply
1 Unassigned
2 Unassigned
3 Destination Unreachable 0 Net Unreachable

1 Host Unreachable

2 Protocol Unreachable

3 Port Unreachable

4 Fragmentation Needed and Don't Fragment was Set

5 Source Route Failed

6 Destination Network Unknown

7 Destination Host Unknown

8 Source Host Isolated

9 Communication with Destination Network is Administratively Prohibited

10 Communication with Destination Host is Administratively Prohibited

11 Destination Network Unreachable for Type of Service

12 Destination Host Unreachable for Type of Service

13 Communication Administratively Prohibited

14 Host Precedence Violation

15 Precedence cutoff in effect
4 Source Quench
5 Redirect 0 Redirect Datagram for the Network (or subnet)

1 Redirect Datagram for the Host

2 Redirect Datagram for the Type of Service and Network

3 Redirect Datagram for the Type of Service and Host
6 Alternate Host Address
7 Unassigned
8 Echo
9 Router Advertisement
10 Router Selection
11 Time Exceeded 0 Time to Live exceeded in Transit

1 Fragment Reassembly Time Exceeded
12 Parameter Problem 0 Pointer indicates the error

1 Missing a Required Option

2 Bad Length
13 Timestamp
14 Timestand Reply
15 Information Request
16 Information Reply
17 Address Mask Request
18 Address Mask Reply
19 Reserved (for Security)
20 - 29 Reserved (for Robustness Experiment)
30 Traceroute
31 Datagram Conversion Error
32 Mobile Host Redirect
33 IPv6 Where-Are-You
34 IPv6 I-Am-Here
35 Mobile Registration
36 Mobile Registration Reply
37 Domain Name Request
38 Domain Name Reply
39 SKIP
40 Photuris
41 - 255 Reserved