It can be with Type or Description ICMP Message Types
Description ICMP Message Types:
ex: iptables -I INPUT -p icmp –icmp-type echo-request -s 1.2.3.4 -j ACCEPT
Type:
ex: iptables -I INPUT -p icmp –icmp-type 8 -s 1.2.3.4 -j ACCEPT
ICMP Message Types
The type field identifies the type of the message sent by the host or gateway. Many of the type fields contain more specific information about the error condition. Table 3.2 lists the ICMP message types.
Table 3.2 ICMP Message Types
| Type | Description ICMP Message Types |
| 0 | Echo Reply (Ping Reply, used with Type 8, Ping Request) |
| 3 | Destination Unreachable |
| 4 | Source Quench |
| 5 | Redirect |
| 8 | Echo Request (Ping Request, used with Type 0, Ping Reply) |
| 9 | Router Advertisement (Used with Type 9) |
| 10 | Router Solicitation (Used with Type 10) |
| 11 | Time Exceeded |
| 12 | Parameter Problem |
| 13 | Timestamp Request (Used with Type 14) |
| 14 | Timestamp Reply (Used with Type 13) |
| 15 | Information Request (obsolete) (Used with Type 16) |
| 16 | Information Reply (obsolete) (Used with Type 15) |
| 17 | Address Mask Request (Used with Type 17) |
| 18 | Address Mask Reply (Used with Type 18) |
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