diff --git a/src/Authentication/NamiGuard.php b/src/Authentication/NamiGuard.php
index 6965b30..45ddcb3 100644
--- a/src/Authentication/NamiGuard.php
+++ b/src/Authentication/NamiGuard.php
@@ -10,6 +10,7 @@ use Illuminate\Contracts\Auth\Authenticatable;
 use Illuminate\Contracts\Auth\Guard;
 use Illuminate\Session\Store as SessionStore;
 use Illuminate\Support\Facades\Cache;
+use Illuminate\Support\Facades\Event;
 use Illuminate\Support\Str;
 use Zoomyboy\LaravelNami\LoginException;
 use Zoomyboy\LaravelNami\Nami;
@@ -21,6 +22,9 @@ class NamiGuard {
 
     protected CacheRepository $cache;
 
+    /** @var <int, callback> $loginCallbacks */
+    public static array $loginCallbacks = [];
+
     /**
      * The currently authenticated user.
      *
@@ -67,34 +71,72 @@ class NamiGuard {
      */
     public function attempt(array $credentials = [], bool $remember = false): bool
     {
+        $beforeResult = static::runBeforeLogin($credentials, $remember);
+
+        if (!is_null($beforeResult)) {
+            return $beforeResult;
+        }
+
         try {
-            $api = Nami::login($credentials['mglnr'], $credentials['password']);
-            $user = $api->findNr($credentials['mglnr']);
-
-            $payload = [
-                'credentials' => $credentials,
-                'firstname' => $user->firstname,
-                'lastname' => $user->lastname,
-                'group_id' => $user->group_id,
-            ];
-
-            $this->setUser(NamiUser::fromPayload($payload));
-            $key = $this->newCacheKey();
-            Cache::forever("namiauth-{$key}", $payload);
-            $this->updateSession($key);
-
-            return true;
+            return $this->login($credentials);
         } catch (LoginException $e) {
             return false;
         }
     }
 
+    /**
+     * @param array<string, string> $credentials
+     */
+    public function login(array $credentials): bool
+    {
+        $api = Nami::login($credentials['mglnr'], $credentials['password']);
+        $user = $api->findNr((int) $credentials['mglnr']);
+
+        $payload = [
+            'credentials' => $credentials,
+            'firstname' => $user->firstname,
+            'lastname' => $user->lastname,
+            'group_id' => $user->group_id,
+        ];
+
+        $this->setUser(NamiUser::fromPayload($payload));
+        $key = $this->newCacheKey();
+        Cache::forever("namiauth-{$key}", $payload);
+        $this->updateSession($key);
+
+        return true;
+    }
+
+    /**
+     * @param array<string, string> $credentials
+     * @param bool $remember
+     */
+    protected function runBeforeLogin(array $credentials, bool $remember): ?bool
+    {
+        foreach (static::$loginCallbacks as $callback) {
+            $result = $callback($credentials, $remember);
+            if ($result !== null) {
+                return $result;
+            }
+        }
+
+        return null;
+    }
+
     protected function updateSession(string $data): void
     {
         $this->session->put($this->getName(), $data);
         $this->session->migrate(true);
     }
 
+    /**
+     * @param callable $callback
+     */
+    public static function beforeLogin(callable $callback): void
+    {
+        static::$loginCallbacks[] = $callback;
+    }
+
     public function getName(): string
     {
         return 'auth_key';