| Type |
Code |
Status |
Description |
| 0 Echo |
0 |
|
Echo reply (used to ping) |
| 1 and 2 |
|
unassigned |
Reserved |
| 3 – Destination Unreachable |
0 |
|
Destination network unreachable |
| 1 |
|
Destination host unreachable |
| 2 |
|
Destination protocol unreachable |
| 3 |
|
Destination port unreachable |
| 4 |
|
Fragmentation required, and DF flag set |
| 5 |
|
Source route failed |
| 6 |
|
Destination 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 unreachable for ToS |
| 13 |
|
Communication administratively prohibited |
| 14 |
|
Host Precedence Violation |
| 15 |
|
Precedence cutoff in effect |
| 4 – Source Quench |
0 |
deprecated |
Source quench (congestion control) |
| 5 – Redirect Message |
0 |
|
Redirect Datagram for the Network |
| 1 |
|
Redirect Datagram for the Host |
| 2 |
|
Redirect Datagram for the ToS & network |
| 3 |
|
Redirect Datagram for the ToS & host |
| 6 |
|
deprecated |
Alternate Host Address |
| 7 |
|
unassigned |
Reserved |
| 8 – Echo Request |
0 |
|
Echo request (used to ping) |
| 9 – Router Advertisement |
0 |
|
Router Advertisement |
| 10 – Router Solicitation |
0 |
|
Router discovery/selection/solicitation |
| 11 – Time Exceeded |
0 |
|
TTL expired in transit |
| 1 |
|
Fragment reassembly time exceeded |
| 12 – Parameter Problem: Bad IP header |
0 |
|
Pointer indicates the error |
| 1 |
|
Missing a required option |
| 2 |
|
Bad length |
| 13 – Timestamp |
0 |
|
Timestamp |
| 14 – Timestamp Reply |
0 |
|
Timestamp reply |
| 15 – Information Request |
0 |
deprecated |
Information Request |
| 16 – Information Reply |
0 |
deprecated |
Information Reply |
| 17 – Address Mask Request |
0 |
deprecated |
Address Mask Request |
| 18 – Address Mask Reply |
0 |
deprecated |
Address Mask Reply |
| 19 |
|
reserved |
Reserved for security |
| 20 through 29 |
|
reserved |
Reserved for robustness experiment |
| 30 – Traceroute |
0 |
deprecated |
Information Request |
| 31 |
|
deprecated |
Datagram Conversion Error |
| 32 |
|
deprecated |
Mobile Host Redirect |
| 33 |
|
deprecated |
Where-Are-You (originally meant for IPv6) |
| 34 |
|
deprecated |
Here-I-Am (originally meant for IPv6) |
| 35 |
|
deprecated |
Mobile Registration Request |
| 36 |
|
deprecated |
Mobile Registration Reply |
| 37 |
|
deprecated |
Domain Name Request |
| 38 |
|
deprecated |
Domain Name Reply |
| 39 |
|
deprecated |
SKIP Algorithm Discovery Protocol, Simple Key-Management for Internet Protocol |
| 40 |
|
|
Photuris, Security failures |
| 41 |
|
experimental |
ICMP for experimental mobility protocols such as Seamoby [RFC4065] |
| 42 through 252 |
|
unassigned |
Reserved |
| 253 |
|
experimental |
RFC3692-style Experiment 1 (RFC 4727) |
| 254 |
|
experimental |
RFC3692-style Experiment 2 (RFC 4727) |
| 255 |
|
reserved |
Reserved |
[…] ICMP is an very commonly used protocol to identify live hosts, It is used by network devices like switches, Routers for sending error messages and operational information’s, for instance service is not available OR the host/server is reachable.You find the most detailed and types of ICMP code’s here. […]
[…] operates by sending Internet Control Message Protocol (ICMP) Echo Request packets to the target host and waiting for an ICMP Echo […]