This is a complete listing of all ICMP types. Note the reference pointing to the RFC or person who introduced the type and code. For a complete and absolute up to date listing of all ICMP types and codes, look at the icmp-parameters document at Internet Assigned Numbers Authority.
Iptables and netfilter uses ICMP type 255 internally since it is not reserved for any real usage, and most likely will never have any real usage. If you set a rule to match iptables -A INPUT -p icmp --icmp-type 255 -j DROP, this will DROP all ICMP packets. It is in other words used to match all ICMP types. |
Table C-1. ICMP types
TYPE | CODE | Description | Query | Error | Reference |
---|---|---|---|---|---|
0 | 0 | Echo Reply | x | RFC792 | |
3 | 0 | Network Unreachable | x | RFC792 | |
3 | 1 | Host Unreachable | x | RFC792 | |
3 | 2 | Protocol Unreachable | x | RFC792 | |
3 | 3 | Port Unreachable | x | RFC792 | |
3 | 4 | Fragmentation needed but no frag. bit set | x | RFC792 | |
3 | 5 | Source routing failed | x | RFC792 | |
3 | 6 | Destination network unknown | x | RFC792 | |
3 | 7 | Destination host unknown | x | RFC792 | |
3 | 8 | Source host isolated (obsolete) | x | RFC792 | |
3 | 9 | Destination network administratively prohibited | x | RFC792 | |
3 | 10 | Destination host administratively prohibited | x | RFC792 | |
3 | 11 | Network unreachable for TOS | x | RFC792 | |
3 | 12 | Host unreachable for TOS | x | RFC792 | |
3 | 13 | Communication administratively prohibited by filtering | x | RFC1812 | |
3 | 14 | Host precedence violation | x | RFC1812 | |
3 | 15 | Precedence cutoff in effect | x | RFC1812 | |
4 | 0 | Source quench | RFC792 | ||
5 | 0 | Redirect for network | RFC792 | ||
5 | 1 | Redirect for host | |||
5 | 2 | Redirect for TOS and network | RFC792 | ||
5 | 3 | Redirect for TOS and host | RFC792 | ||
8 | 0 | Echo request | x | RFC792 | |
9 | 0 | Router advertisement - Normal router advertisement | RFC1256 | ||
9 | 16 | Router advertisement - Does not route common traffic | RFC2002 | ||
10 | 0 | Route selection | RFC1256 | ||
11 | 0 | TTL equals 0 during transit | x | RFC792 | |
11 | 1 | TTL equals 0 during reassembly | x | RFC792 | |
12 | 0 | IP header bad (catchall error) | x | RFC792 | |
12 | 1 | Required options missing | x | RFC1108 | |
12 | 2 | IP Header bad length | x | RFC792 | |
13 | 0 | Timestamp request (obsolete) | x | RFC792 | |
14 | Timestamp reply (obsolete) | x | RFC792 | ||
15 | 0 | Information request (obsolete) | x | RFC792 | |
16 | 0 | Information reply (obsolete) | x | RFC792 | |
17 | 0 | Address mask request | x | RFC950 | |
18 | 0 | Address mask reply | x | RFC950 | |
20-29 | Reserved for robustness experiment | Zaw-Sing Su | |||
30 | 0 | Traceroute | x | RFC1393 | |
31 | 0 | Datagram Conversion Error | x | RFC1475 | |
32 | 0 | Mobile Host Redirect | David Johnson | ||
33 | 0 | IPv6 Where-Are-You | x | Bill Simpson | |
34 | 0 | IPv6 I-Am-Here | x | Bill Simpson | |
35 | 0 | Mobile Registration Request | x | Bill Simpson | |
36 | 0 | Mobile Registration Reply | x | Bill Simpson | |
39 | 0 | SKIP | Tom Markson | ||
40 | 0 | Photuris | RFC2521 |
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