| icmp_destunreach_rate |
| || Maximum rate to send ICMP Destination Unreachable packets. This limits the rate at which packets are sent to any individual route or destination. The limit does not affect sending of ICMP_FRAG_NEEDED packets needed for path MTU discovery. |
| icmp_echo_ignore_all |
| || If this value is non-zero, Linux will ignore all ICMP_ECHO requests. |
| icmp_echo_ignore_broadcasts |
| || If this value is non-zero, Linux will ignore all ICMP_ECHO packets sent to broadcast addresses. |
| icmp_echoreply_rate |
| || Maximum rate for sending ICMP_ECHOREPLY packets in response to ICMP_ECHOREQUEST packets. |
| icmp_paramprob_rate |
| || Maximum rate for sending ICMP_PARAMETERPROB packets. These packets are sent when a packet arrives with an invalid IP header. |
| icmp_timeexceed_rate |
| || Maximum rate for sending ICMP_TIME_EXCEEDED packets. These packets are sent to prevent loops when a packet has crossed too many hops. |
As many other implementations dont support IPPROTO_ICMP raw sockets, this feature should not be relied on in portable programs.
ICMP_REDIRECT packets are not sent when Linux is not acting as a router. They are also only accepted from the old gateway defined in the routing table and the redirect routes are expired after some time.
The 64-bit timestamp returned by ICMP_TIMESTAMP is in milliseconds since January 1, 1970.
Linux ICMP internally uses a raw socket to send ICMPs. This raw socket may appear in netstat(8) output with a zero inode.
Support for the ICMP_ADDRESS request was removed in 2.2.
Support for ICMP_SOURCE_QUENCH was removed in Linux 2.2.