static int in_cksum(u_short *addr, int len);
static void read_icmp_data(monitor_host_t *p);
static void tvsub(struct timeval *out, struct timeval *in);
static int in_cksum(u_short *addr, int len);
static void read_icmp_data(monitor_host_t *p);
static void tvsub(struct timeval *out, struct timeval *in);