diff --git a/internal/auth/auth.go b/internal/auth/auth.go
index c51d487..2d2c513 100644
--- a/internal/auth/auth.go
+++ b/internal/auth/auth.go
@@ -32,8 +32,10 @@ const (
 	argonThreads = 4
 	argonKeyLen  = 32
 
-	maxFailures   = 5
+	// 同一来源在窗口内累计失败 maxFailures 次（登录与分享密码合计）即封禁 lockout
+	maxFailures   = 30
 	failureWindow = 15 * time.Minute
+	lockout       = 15 * time.Minute
 )
 
 var (
@@ -52,10 +54,12 @@ type Manager struct {
 
 	mu       sync.Mutex
 	failures map[string][]time.Time
+	blocked  map[string]time.Time // 来源 -> 解封时间
+	now      func() time.Time
 }
 
 func New(s *store.Store) (*Manager, error) {
-	m := &Manager{store: s, failures: map[string][]time.Time{}}
+	m := &Manager{store: s, failures: map[string][]time.Time{}, blocked: map[string]time.Time{}, now: time.Now}
 	ok, err := m.IsSetUp()
 	if err != nil {
 		return nil, err
@@ -149,7 +153,8 @@ func HashSharePassword(password string) string {
 	return hashPassword(password)
 }
 
-// CheckSharePassword 校验分享密码，与登录共用按来源的失败限速
+// CheckSharePassword 校验分享密码，与登录共用按来源的失败限速。
+// 成功不清零失败计数：否则知道某个分享密码的人可以借此反复重置计数，无限尝试登录密码
 func (m *Manager) CheckSharePassword(ip, hash, password string) error {
 	if !m.allow(ip) {
 		return ErrRateLimited
@@ -225,26 +230,37 @@ func (m *Manager) ValidateAPIToken(plain string) (scope string, ok bool, err err
 	return m.store.UseAPIToken(hashToken(plain), time.Now().UnixMilli())
 }
 
-// ---- 限速：同一来源在时间窗口内失败过多则拒绝 ----
+// ---- 限速：同一来源在时间窗口内失败过多则封禁一段时间 ----
 
 func (m *Manager) allow(ip string) bool {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	cutoff := time.Now().Add(-failureWindow)
+	until, ok := m.blocked[ip]
+	if ok && m.now().Before(until) {
+		return false
+	}
+	delete(m.blocked, ip)
+	return true
+}
+
+func (m *Manager) recordFailure(ip string) {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	now := m.now()
+	cutoff := now.Add(-failureWindow)
 	recent := m.failures[ip][:0]
 	for _, t := range m.failures[ip] {
 		if t.After(cutoff) {
 			recent = append(recent, t)
 		}
 	}
+	recent = append(recent, now)
+	if len(recent) >= maxFailures {
+		m.blocked[ip] = now.Add(lockout)
+		delete(m.failures, ip)
+		return
+	}
 	m.failures[ip] = recent
-	return len(recent) < maxFailures
-}
-
-func (m *Manager) recordFailure(ip string) {
-	m.mu.Lock()
-	m.failures[ip] = append(m.failures[ip], time.Now())
-	m.mu.Unlock()
 }
 
 func (m *Manager) clearFailures(ip string) {
diff --git a/internal/auth/auth_test.go b/internal/auth/auth_test.go
new file mode 100644
index 0000000..53141d5
--- /dev/null
+++ b/internal/auth/auth_test.go
@@ -0,0 +1,94 @@
+package auth
+
+import (
+	"errors"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"rawmark/internal/store"
+)
+
+func newManager(t *testing.T) (*Manager, *time.Time) {
+	t.Helper()
+	st, err := store.Open(filepath.Join(t.TempDir(), "rawmark.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(func() { st.Close() })
+	m, err := New(st)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := m.Setup(m.SetupCode(), "password123"); err != nil {
+		t.Fatal(err)
+	}
+	clock := time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC)
+	m.now = func() time.Time { return clock }
+	return m, &clock
+}
+
+// 登录与分享密码合计 30 次失败后封禁 15 分钟，期间正确密码也被拒绝
+func TestRateLimit(t *testing.T) {
+	m, clock := newManager(t)
+	share := HashSharePassword("share-pass")
+	for i := 0; i < maxFailures-1; i++ {
+		var err error
+		if i%2 == 0 {
+			_, err = m.Login("1.1.1.1", "wrong")
+		} else {
+			err = m.CheckSharePassword("1.1.1.1", share, "wrong")
+		}
+		if !errors.Is(err, ErrBadCredentials) {
+			t.Fatalf("第 %d 次失败: %v", i+1, err)
+		}
+	}
+	// 分享密码正确不清零计数
+	if err := m.CheckSharePassword("1.1.1.1", share, "share-pass"); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := m.Login("1.1.1.1", "wrong"); !errors.Is(err, ErrBadCredentials) {
+		t.Fatalf("第 30 次失败: %v", err)
+	}
+	if _, err := m.Login("1.1.1.1", "password123"); !errors.Is(err, ErrRateLimited) {
+		t.Fatalf("封禁期间正确密码也应被拒绝: %v", err)
+	}
+	if err := m.CheckSharePassword("1.1.1.1", share, "share-pass"); !errors.Is(err, ErrRateLimited) {
+		t.Fatalf("封禁同样作用于分享密码: %v", err)
+	}
+	if _, err := m.Login("2.2.2.2", "password123"); err != nil {
+		t.Fatalf("其他来源不受影响: %v", err)
+	}
+	*clock = clock.Add(lockout - time.Second)
+	if _, err := m.Login("1.1.1.1", "password123"); !errors.Is(err, ErrRateLimited) {
+		t.Fatalf("未满 15 分钟仍封禁: %v", err)
+	}
+	*clock = clock.Add(time.Second)
+	if _, err := m.Login("1.1.1.1", "password123"); err != nil {
+		t.Fatalf("15 分钟后解封: %v", err)
+	}
+}
+
+// 窗口外的失败不计入；登录成功清零
+func TestRateLimitWindow(t *testing.T) {
+	m, clock := newManager(t)
+	for i := 0; i < maxFailures-1; i++ {
+		m.Login("1.1.1.1", "wrong")
+	}
+	*clock = clock.Add(failureWindow + time.Second)
+	for i := 0; i < maxFailures-1; i++ {
+		m.Login("1.1.1.1", "wrong")
+	}
+	if _, err := m.Login("1.1.1.1", "password123"); err != nil {
+		t.Fatalf("15 分钟前的失败不应计入: %v", err)
+	}
+	for i := 0; i < maxFailures-1; i++ {
+		m.Login("1.1.1.1", "wrong")
+	}
+	if _, err := m.Login("1.1.1.1", "wrong"); !errors.Is(err, ErrBadCredentials) {
+		t.Fatalf("登录成功后计数应已清零: %v", err)
+	}
+	if _, err := m.Login("1.1.1.1", "password123"); !errors.Is(err, ErrRateLimited) {
+		t.Fatalf("清零后再失败 30 次应封禁: %v", err)
+	}
+}