.webp?w=696&resize=696,0&ssl=1 "ICMP Types and Codes")
Control messages
| 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 |
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