diff --git a/src/Basis.php b/src/Basis.php
index 13461c4..77de02f 100644
--- a/src/Basis.php
+++ b/src/Basis.php
@@ -12,6 +12,20 @@ function lenUtf8(string $str): int { // get string length (Chinese -> 2)
     return strlen(iconv('utf-8', 'gb2312', $str));
 }
 
+function isIPv4($ip): bool {
+    return filter_var($ip, \FILTER_VALIDATE_IP, \FILTER_FLAG_IPV4);
+}
+
+function isIPv6($ip): bool {
+    return filter_var($ip, \FILTER_VALIDATE_IP, \FILTER_FLAG_IPV6);
+}
+
+function isDomain($domain): bool {
+    $regex = '/^(?=^.{3,255}$)[a-zA-Z0-9][-a-zA-Z0-9]{0,62}(\.[a-zA-Z0-9][-a-zA-Z0-9]{0,62})+$/';
+    preg_match($regex, $domain, $match);
+    return count($match) != 0;
+}
+
 function getKeys(bool $isWinServer = false): array { // get kms keys asset
     $keysAsset = json_decode(file_get_contents('../assets/kms-keys.json'), true);
     return $isWinServer ? array_reverse($keysAsset['win-server']) : $keysAsset['win'];
diff --git a/src/Check.php b/src/Check.php
index 4842b95..c3079e1 100644
--- a/src/Check.php
+++ b/src/Check.php
@@ -1,15 +1,46 @@
 <?php
 
+require_once 'Basis.php';
 require_once 'Process.php';
 
-function kmsCheck(string $host, int $port = 1688): bool {
-    # TODO: ipv6 host add bracket
-    $vlmcs = new Process(['vlmcs', $host . ':' . $port], $capture = true);
+function vlmcsCheck(string $host, int $port = 1688): bool {
+    $host = str_contains($host, ':') ? "[$host]" : $host; // ipv6 add bracket
+    $vlmcs = new Process(['vlmcs', $host . ':' . $port], true);
     while($vlmcs->isAlive()); // wait vlmcs exit
     preg_match_all('/Sending activation request \(KMS V6\)/', $vlmcs->getStdout(), $match);
     return count($match[0]) != 0;
 }
 
-$host = 'kms.343.re';
-echo "check $host -> ";
-echo (kmsCheck($host) ? 'yes' : 'no') . PHP_EOL;
+function kmsCheck(): array {
+    if (!isset($_GET['host'])) { // missing host param
+        return array(
+            'success' => false,
+            'message' => 'missing host param'
+        );
+    }
+    $host = $_GET['host'];
+    if (!isIPv4($host) and !isIPv6($host) and !isDomain($host)) { // invalid host
+        return array(
+            'success' => false,
+            'message' => 'invalid host'
+        );
+    }
+    $port = $_GET['port'] ?? 1688;
+    if ($port > 65535 or $port < 0) { // invalid port
+        return array(
+            'success' => false,
+            'message' => 'invalid port'
+        );
+    }
+    if (vlmcsCheck($host, $port)) { // KMS server available
+        return array(
+            'success' => true,
+            'message' => 'kms server available'
+        );
+    } else { // KMS server couldn't reach
+        return array(
+            'success' => false,
+            'message' => 'kms server connect failed'
+        );
+    }
+}
diff --git a/src/Route.php b/src/Route.php
index 6738798..6504a40 100644
--- a/src/Route.php
+++ b/src/Route.php
@@ -1,6 +1,7 @@
 <?php
 
 require_once 'Basis.php';
+require_once 'Check.php';
 require_once 'KmsCli.php';
 require_once 'KmsWeb.php';
 
@@ -35,7 +36,7 @@ if ($url == '/' or $url == '/help') {
     }
 } else if ($url == '/check') {
     mimeJson();
-    echo "WIP..."; // TODO: kms check
+    echo json_encode(kmsCheck()); // check kms server
 } else { // unknown request
     if ($isCli) {
         echo "Illegal Request\n";