PHP ping

 <?php
 /// start ping.inc.php ///

 $g_icmp_error = "No Error";

 // timeout in ms
 function ping($host, $timeout)
 {
     $port = 0;
     $datasize = 64;
     global $g_icmp_error;
     $g_icmp_error = "No Error";
     $ident = array(ord('J'), ord('C'));
     $seq = array(rand(0, 255), rand(0, 255));

     $packet = '';
     $packet .= chr(8); // type = 8 : request
     $packet .= chr(0); // code = 0

     $packet .= chr(0); // checksum init
     $packet .= chr(0); // checksum init

     $packet .= chr($ident[0]); // identifier
     $packet .= chr($ident[1]); // identifier

     $packet .= chr($seq[0]); // seq
     $packet .= chr($seq[1]); // seq

     for ($i = 0; $i < $datasize; $i++)
         $packet .= chr(0);

     $chk = icmpChecksum($packet);

     $packet[2] = $chk[0]; // checksum init
     $packet[3] = $chk[1]; // checksum init

     $sock = socket_create(AF_INET, SOCK_RAW, getprotobyname('icmp'));
     $time_start = microtime(true);
     socket_sendto($sock, $packet, strlen($packet), 0, $host, $port);

     $read = array($sock);
     $write = NULL;
     $except = NULL;

     $select = socket_select($read, $write, $except, 0, $timeout * 1000);
     if ($select === NULL) {
         $g_icmp_error = "Select Error";
         socket_close($sock);
         return -1;
     } elseif ($select === 0) {
         $g_icmp_error = "Timeout";
         socket_close($sock);
         return -1;
     }

     $recv = '';
     $time_stop = microtime(true);
     socket_recvfrom($sock, $recv, 65535, 0, $host, $port);
     $recv = unpack('C*', $recv);

     if ($recv[10] !== 1) // ICMP proto = 1
     {
         $g_icmp_error = "Not ICMP packet";
         socket_close($sock);
         return -1;
     }

     if ($recv[21] !== 0) // ICMP response = 0
     {
         $g_icmp_error = "Not ICMP response";
         socket_close($sock);
         return -1;
     }

     if ($ident[0] !== $recv[25] || $ident[1] !== $recv[26]) {
         $g_icmp_error = "Bad identification number";
         socket_close($sock);
         return -1;
     }

     if ($seq[0] !== $recv[27] || $seq[1] !== $recv[28]) {
         $g_icmp_error = "Bad sequence number";
         socket_close($sock);
         return -1;
     }

     $ms = bcmul(bcsub($time_stop, $time_start, 6), 1000);

     if ($ms < 0) {
         $g_icmp_error = "Response too long";
         $ms = -1;
     }

     socket_close($sock);

     return $ms;
 }

 function icmpChecksum($data)
 {
     $bit = unpack('n*', $data);
     $sum = array_sum($bit);

     if (strlen($data) % 2) {
         $temp = unpack('C*', $data[strlen($data) - 1]);
         $sum += $temp[1];
     }

     $sum = ($sum >> 16) + ($sum & 0xffff);
     $sum += ($sum >> 16);

     return pack('n*', ~$sum);
 }

 function getLastIcmpError()
 {
     global $g_icmp_error;
     return $g_icmp_error;
 }
 /// end ping.inc.php ///

使用方法:

$ping = ping('www.baidu.com',200);
if ($ping > 0) {
    // ok
} else {
    // failed
}