Chapter 7 Firewall : Firewall objects : Services and TCP ports : Protocol Types : ICMP Types and Codes
  
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.
Table 37: 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