+extern int sysctl_icmp_echo_ignore_all;
+extern int sysctl_icmp_echo_ignore_broadcasts;
+extern int sysctl_icmp_ignore_bogus_error_responses;
+extern int sysctl_icmp_errors_use_inbound_ifaddr;
+extern int sysctl_icmp_ratelimit;
+extern int sysctl_icmp_ratemask;