diff --git a/app/Server/Factory.php b/app/Server/Factory.php
index 35e3e3b..5c56987 100644
--- a/app/Server/Factory.php
+++ b/app/Server/Factory.php
@@ -38,6 +38,7 @@
 use App\Server\Http\Controllers\Admin\StoreUsersController;
 use App\Server\Http\Controllers\ControlMessageController;
 use App\Server\Http\Controllers\TunnelMessageController;
+use App\Server\Http\Controllers\ValidateTunnelController;
 use App\Server\Http\Router;
 use App\Server\LoggerRepository\NullLogger;
 use App\Server\StatisticsCollector\DatabaseStatisticsCollector;
@@ -166,6 +167,17 @@ protected function addAdminRoutes()
 
         $this->router->get('/api/tcp', GetTcpConnectionsController::class, $adminCondition);
         $this->router->delete('/api/tcp/{id}', DisconnectTcpConnectionController::class, $adminCondition);
+
+        return $this;
+    }
+
+    protected function addValidateTunnel()
+    {
+        $localCondition = 'request.headers.get("Host") matches "/^'.$this->host.':'.$this->port.'$/i"';
+
+        $this->router->get('/validate-tunnel', ValidateTunnelController::class, $localCondition);
+
+        return $this;
     }
 
     protected function bindConfiguration()
@@ -209,7 +221,8 @@ public function createServer()
             ->ensureDatabaseIsInitialized()
             ->registerStatisticsCollector()
             ->bindConnectionManager()
-            ->addAdminRoutes();
+            ->addAdminRoutes()
+            ->addValidateTunnel();
 
         $controlConnection = $this->addControlConnectionRoute();
 
diff --git a/app/Server/Http/Controllers/ValidateTunnelController.php b/app/Server/Http/Controllers/ValidateTunnelController.php
new file mode 100644
index 0000000..91107a9
--- /dev/null
+++ b/app/Server/Http/Controllers/ValidateTunnelController.php
@@ -0,0 +1,109 @@
+<?php
+
+namespace App\Server\Http\Controllers;
+
+use App\Contracts\ConnectionManager;
+use App\Http\Controllers\Controller;
+use App\Server\Configuration;
+use App\Server\Connections\ControlConnection;
+use Illuminate\Http\Request;
+use Ratchet\ConnectionInterface;
+
+class ValidateTunnelController extends Controller
+{
+    private ConnectionManager $connectionManager;
+    private Configuration $configuration;
+
+    public function __construct(
+        Configuration $configuration,
+        ConnectionManager $connectionManager,
+    ) {
+        $this->connectionManager = $connectionManager;
+        $this->configuration = $configuration;
+    }
+
+    public function handle(Request $request, ConnectionInterface $httpConnection)
+    {
+        $key = $request->get('key');
+
+        // Only allow requests with the correct key
+        if ($key !== $this->getAuthorizedKey()) {
+            $httpConnection->send(
+                respond_json(['exists' => false], 401),
+            );
+            $httpConnection->close();
+
+            return;
+        }
+
+        $domain = $request->get('domain');
+        if ($domain === null) {
+            $httpConnection->send(
+                respond_json(['exists' => false, 'error' => 'invalid_domain'], 404),
+            );
+            $httpConnection->close();
+
+            return;
+        }
+
+        // If the domain is the same as the hostname, then it requested the main domain
+        $hostname = $this->configuration->hostname();
+        if ($hostname === $domain) {
+            $this->isSuccessful($httpConnection);
+
+            return;
+        }
+
+        // Also allow the admin dashboard
+        $adminSubdomain = config('expose.admin.subdomain');
+        if ($domain === $adminSubdomain.'.'.$hostname) {
+            $this->isSuccessful($httpConnection);
+
+            return;
+        }
+
+        // Check if the domain is a tunnel
+        $sites = collect($this->connectionManager->getConnections())
+            ->filter(function ($site) use ($domain) {
+                $isControlConnection = get_class($site) === ControlConnection::class;
+                if (! $isControlConnection) {
+                    return false;
+                }
+
+                $fqdn = sprintf(
+                    '%s.%s',
+                    $site->subdomain,
+                    $site->serverHost,
+                );
+
+                return $fqdn === $domain;
+            })
+            ->map(function (ControlConnection $site) {
+                return sprintf(
+                    '%s.%s',
+                    $site->host,
+                    $site->subdomain,
+                );
+            });
+
+        if ($sites->count() > 0) {
+            $this->isSuccessful($httpConnection);
+
+            return;
+        }
+
+        $httpConnection->send(respond_json(['exists' => false, 'error' => 'no_tunnel_found'], 404));
+        $httpConnection->close();
+    }
+
+    private function isSuccessful(ConnectionInterface $connection): void
+    {
+        $connection->send(respond_json(['exists' => true]));
+        $connection->close();
+    }
+
+    private function getAuthorizedKey(): string
+    {
+        return config('expose.validate_tunnel.authorized_key');
+    }
+}
diff --git a/config/expose.php b/config/expose.php
index 8ca4f57..4249fcc 100644
--- a/config/expose.php
+++ b/config/expose.php
@@ -390,4 +390,8 @@
             'repository' => \App\Server\StatisticsRepository\DatabaseStatisticsRepository::class,
         ],
     ],
+
+    'validate_tunnel' => [
+        'authorized_key' => 'asHzMGp4y4fYmNzWAUmgsZZbcjSM5e',
+    ],
 ];