diff --git a/lua/server/request.lua b/lua/server/request.lua
index ef99949d..335d03ee 100644
--- a/lua/server/request.lua
+++ b/lua/server/request.lua
@@ -36,7 +36,7 @@ local function tellRoomToObserver(self, player)
   player:doNotify("UpdateDrawPile", #self.draw_pile)
   player:doNotify("UpdateRoundNum", self:getTag("RoundCount") or 0)
 
-  table.insert(self.observers, {observee.id, player})
+  table.insert(self.observers, {observee.id, player, player:getId()})
 end
 
 local function addObserver(self, id)
@@ -56,12 +56,10 @@ end
 
 local function removeObserver(self, id)
   for _, t in ipairs(self.observers) do
-    local __, p = table.unpack(t)
-    if p:getId() == id then
+    local pid = t[3]
+    if pid == id then
       table.removeOne(self.observers, t)
-      self:doBroadcastNotify("RemoveObserver", json.encode{
-        p:getId(),
-      })
+      self:doBroadcastNotify("RemoveObserver", json.encode{ pid })
       break
     end
   end
diff --git a/lua/server/serverplayer.lua b/lua/server/serverplayer.lua
index 12b688af..028934da 100644
--- a/lua/server/serverplayer.lua
+++ b/lua/server/serverplayer.lua
@@ -47,7 +47,7 @@ function ServerPlayer:doNotify(command, jsonData)
   local room = self.room
   for _, t in ipairs(room.observers) do
     local id, p = table.unpack(t)
-    if id == self.id then
+    if id == self.id and room.room:hasObserver(p) then
       p:doNotify(command, jsonData)
     end
   end
diff --git a/server/init.sql b/server/init.sql
index 6072d2ab..b7d86b84 100644
--- a/server/init.sql
+++ b/server/init.sql
@@ -16,6 +16,15 @@ CREATE TABLE IF NOT EXISTS banip (
   ip VARCHAR(64)
 );
 
+CREATE TABLE IF NOT EXISTS uuidinfo (
+  id INTEGER PRIMARY KEY,
+  uuid VARCHAR(32)
+);
+
+CREATE TABLE IF NOT EXISTS banuuid (
+  uuid VARCHAR(32)
+);
+
 -- 胜率相关
 
 CREATE TABLE IF NOT EXISTS winRate (
diff --git a/src/core/util.cpp b/src/core/util.cpp
index ed679644..d4e7a1c9 100644
--- a/src/core/util.cpp
+++ b/src/core/util.cpp
@@ -4,6 +4,7 @@
 #include <qcryptographichash.h>
 #include <qnamespace.h>
 #include <qregularexpression.h>
+#include <QSysInfo>
 
 extern "C" {
 int luaopen_fk(lua_State *);
@@ -203,6 +204,10 @@ QJsonDocument String2Json(const QString &str) {
   return QJsonDocument::fromJson(bytes);
 }
 
+QString GetDeviceUuid() {
+  return QSysInfo::machineUniqueId();
+}
+
 QString Color(const QString &raw, fkShell::TextColor color,
               fkShell::TextType type) {
 #ifdef Q_OS_LINUX
diff --git a/src/core/util.h b/src/core/util.h
index 1a18ad60..72daff01 100644
--- a/src/core/util.h
+++ b/src/core/util.h
@@ -20,6 +20,8 @@ QString calcFileMD5();
 QByteArray JsonArray2Bytes(const QJsonArray &arr);
 QJsonDocument String2Json(const QString &str);
 
+QString GetDeviceUuid();
+
 namespace fkShell {
   enum TextColor {
     Black,
diff --git a/src/server/room.cpp b/src/server/room.cpp
index b9f0e2f9..b859b93d 100644
--- a/src/server/room.cpp
+++ b/src/server/room.cpp
@@ -5,7 +5,12 @@
 #include <qjsonarray.h>
 #include <qjsondocument.h>
 
+#ifdef FK_SERVER_ONLY
+static void *ClientInstance = nullptr;
+#else
 #include "client.h"
+#endif
+
 #include "client_socket.h"
 #include "roomthread.h"
 #include "server.h"
@@ -268,15 +273,15 @@ void Room::removePlayer(ServerPlayer *player) {
     // 原先的跑路机器人会在游戏结束后自动销毁掉
     server->addPlayer(runner);
 
-    // 如果走小道的人不是单机启动玩家 那么直接ban
-    if (!ClientInstance && !player->isDied()) {
-      server->temporarilyBan(runner->getId());
-    }
-
     m_thread->wakeUp();
 
     // 发出信号，让大厅添加这个人
     emit playerRemoved(runner);
+
+    // 如果走小道的人不是单机启动玩家 那么直接ban
+    if (!ClientInstance && !player->isDied()) {
+      server->temporarilyBan(runner->getId());
+    }
   }
 
   // 如果房间空了，就把房间标为废弃，Server有信号处理函数的
@@ -341,6 +346,8 @@ void Room::removeObserver(ServerPlayer *player) {
 
 QList<ServerPlayer *> Room::getObservers() const { return observers; }
 
+bool Room::hasObserver(ServerPlayer *player) const { return observers.contains(player); }
+
 int Room::getTimeout() const { return timeout; }
 
 void Room::setTimeout(int timeout) { this->timeout = timeout; }
diff --git a/src/server/room.h b/src/server/room.h
index 424a9699..ad7a4b90 100644
--- a/src/server/room.h
+++ b/src/server/room.h
@@ -45,6 +45,7 @@ class Room : public QObject {
   void addObserver(ServerPlayer *player);
   void removeObserver(ServerPlayer *player);
   QList<ServerPlayer *> getObservers() const;
+  bool hasObserver(ServerPlayer *player) const;
 
   int getTimeout() const;
   void setTimeout(int timeout);
diff --git a/src/server/server.cpp b/src/server/server.cpp
index a02b4631..748f8836 100644
--- a/src/server/server.cpp
+++ b/src/server/server.cpp
@@ -273,7 +273,7 @@ void Server::processRequest(const QByteArray &msg) {
         doc[2] != "Setup")
       valid = false;
     else
-      valid = (String2Json(doc[3].toString()).array().size() == 4);
+      valid = (String2Json(doc[3].toString()).array().size() == 5);
   }
 
   if (!valid) {
@@ -313,13 +313,34 @@ void Server::processRequest(const QByteArray &msg) {
     return;
   }
 
+  auto uuid = arr[4].toString();
+  auto result2 = QJsonArray({1});
+  if (CheckSqlString(uuid)) {
+    result2 = SelectFromDatabase(
+        db, QString("SELECT * FROM banuuid WHERE uuid='%1';").arg(uuid));
+  }
+
+  if (!result2.isEmpty()) {
+    QJsonArray body;
+    body << -2;
+    body << (Router::TYPE_NOTIFICATION | Router::SRC_SERVER |
+             Router::DEST_CLIENT);
+    body << "ErrorMsg";
+    body << "you have been banned!";
+    client->send(JsonArray2Bytes(body));
+    qInfo() << "Refused banned UUID:" << uuid;
+    client->disconnectFromHost();
+    return;
+  }
+
   handleNameAndPassword(client, arr[0].toString(), arr[1].toString(),
-                        arr[2].toString());
+                        arr[2].toString(), uuid);
 }
 
 void Server::handleNameAndPassword(ClientSocket *client, const QString &name,
                                    const QString &password,
-                                   const QString &md5_str) {
+                                   const QString &md5_str,
+                                   const QString &uuid_str) {
   auto encryted_pw = QByteArray::fromBase64(password.toLatin1());
   unsigned char buf[4096] = {0};
   RSA_private_decrypt(RSA_size(rsa), (const unsigned char *)encryted_pw.data(),
@@ -462,6 +483,9 @@ void Server::handleNameAndPassword(ClientSocket *client, const QString &name,
             .arg(obj["id"].toString().toInt());
     ExecSQL(db, sql_update);
 
+    auto uuid_update = QString("REPLACE INTO uuidinfo (id, uuid) VALUES (%1, '%2');").arg(obj["id"].toString().toInt()).arg(uuid_str);
+    ExecSQL(db, uuid_update);
+
     // create new ServerPlayer and setup
     ServerPlayer *player = new ServerPlayer(lobby());
     player->setSocket(client);
diff --git a/src/server/server.h b/src/server/server.h
index 02196c64..2e3ddd19 100644
--- a/src/server/server.h
+++ b/src/server/server.h
@@ -86,7 +86,7 @@ private:
   void readConfig();
 
   void handleNameAndPassword(ClientSocket *client, const QString &name,
-                             const QString &password, const QString &md5_str);
+                             const QString &password, const QString &md5_str, const QString &uuid_str);
   void processDatagram(const QByteArray &msg, const QHostAddress &addr, uint port);
 };
 
diff --git a/src/server/shell.cpp b/src/server/shell.cpp
index ae322669..3724f132 100644
--- a/src/server/shell.cpp
+++ b/src/server/shell.cpp
@@ -29,16 +29,24 @@ void Shell::helpCommand(QStringList &) {
   HELP_MSG("%s: List all running rooms.", "lsroom");
   HELP_MSG("%s: Kick a player by his <id>.", "kick");
   HELP_MSG("%s: Broadcast message.", "msg");
-  HELP_MSG("%s: Ban 1 or more accounts by their <name>.", "ban");
+  HELP_MSG("%s: Ban 1 or more accounts, IP, UUID by their <name>.", "ban");
   HELP_MSG("%s: Unban 1 or more accounts by their <name>.", "unban");
   HELP_MSG(
-      "%s: Ban 1 or more IP address according to somebody's 'lastLoginIp'. "
+      "%s: Ban 1 or more IP address. "
       "At least 1 <name> required.",
       "banip");
   HELP_MSG(
-      "%s: Unban 1 or more IP address according to somebody's 'lastLoginIp'. "
+      "%s: Unban 1 or more IP address. "
       "At least 1 <name> required.",
       "unbanip");
+  HELP_MSG(
+      "%s: Ban 1 or more UUID. "
+      "At least 1 <name> required.",
+      "banuuid");
+  HELP_MSG(
+      "%s: Unban 1 or more UUID. "
+      "At least 1 <name> required.",
+      "unbanuuid");
   qInfo();
   qInfo("===== Package commands =====");
   HELP_MSG("%s: Install a new package from <url>.", "install");
@@ -207,6 +215,9 @@ void Shell::banCommand(QStringList &list) {
   foreach (auto name, list) {
     banAccount(db, name, true);
   }
+
+  banipCommand(list);
+  banUuidCommand(list);
 }
 
 void Shell::unbanCommand(QStringList &list) {
@@ -220,7 +231,11 @@ void Shell::unbanCommand(QStringList &list) {
   foreach (auto name, list) {
     banAccount(db, name, false);
   }
+
+  unbanipCommand(list);
+  unbanUuidCommand(list);
 }
+
 static void banIPByName(sqlite3 *db, const QString &name, bool banned) {
   if (!CheckSqlString(name))
     return;
@@ -275,6 +290,65 @@ void Shell::unbanipCommand(QStringList &list) {
   }
 }
 
+static void banUuidByName(sqlite3 *db, const QString &name, bool banned) {
+  if (!CheckSqlString(name))
+    return;
+
+  QString sql_find = QString("SELECT * FROM userinfo \
+        WHERE name='%1';")
+                         .arg(name);
+  auto result = SelectFromDatabase(db, sql_find);
+  if (result.isEmpty())
+    return;
+  auto obj = result[0].toObject();
+  int id = obj["id"].toString().toInt();
+
+  auto result2 = SelectFromDatabase(db, QString("SELECT * FROM uuidinfo WHERE id=%1;").arg(id));
+  if (result2.isEmpty())
+    return;
+
+  auto uuid = result2[0].toObject()["uuid"].toString();
+
+  if (banned) {
+    ExecSQL(db, QString("INSERT INTO banuuid VALUES('%1');").arg(uuid));
+
+    auto p = ServerInstance->findPlayer(id);
+    if (p) {
+      p->kicked();
+    }
+    qInfo("Banned UUID %s.", uuid.toUtf8().constData());
+  } else {
+    ExecSQL(db, QString("DELETE FROM banuuid WHERE uuid='%1';").arg(uuid));
+    qInfo("Unbanned UUID %s.", uuid.toUtf8().constData());
+  }
+}
+
+void Shell::banUuidCommand(QStringList &list) {
+  if (list.isEmpty()) {
+    qWarning("The 'banuuid' command needs at least 1 <name>.");
+    return;
+  }
+
+  auto db = ServerInstance->getDatabase();
+
+  foreach (auto name, list) {
+    banUuidByName(db, name, true);
+  }
+}
+
+void Shell::unbanUuidCommand(QStringList &list) {
+  if (list.isEmpty()) {
+    qWarning("The 'unbanuuid' command needs at least 1 <name>.");
+    return;
+  }
+
+  auto db = ServerInstance->getDatabase();
+
+  foreach (auto name, list) {
+    banUuidByName(db, name, false);
+  }
+}
+
 Shell::Shell() {
   setObjectName("Shell");
   signal(SIGINT, sigintHandler);
@@ -297,6 +371,8 @@ Shell::Shell() {
     handlers["unban"] = &Shell::unbanCommand;
     handlers["banip"] = &Shell::banipCommand;
     handlers["unbanip"] = &Shell::unbanipCommand;
+    handlers["banuuid"] = &Shell::banUuidCommand;
+    handlers["unbanuuid"] = &Shell::unbanUuidCommand;
   }
   handler_map = handlers;
 }
diff --git a/src/server/shell.h b/src/server/shell.h
index 0e4b1564..a1c0b8dc 100644
--- a/src/server/shell.h
+++ b/src/server/shell.h
@@ -27,8 +27,10 @@ private:
   void msgCommand(QStringList &);
   void banCommand(QStringList &);
   void banipCommand(QStringList &);
+  void banUuidCommand(QStringList &);
   void unbanCommand(QStringList &);
   void unbanipCommand(QStringList &);
+  void unbanUuidCommand(QStringList &);
 };
 
 #endif
diff --git a/src/swig/server.i b/src/swig/server.i
index edd4775e..f352d95d 100644
--- a/src/swig/server.i
+++ b/src/swig/server.i
@@ -11,6 +11,7 @@ public:
   QList<ServerPlayer *> getPlayers() const;
 
   QList<ServerPlayer *> getObservers() const;
+  bool hasObserver(ServerPlayer *player) const;
   int getTimeout() const;
   void checkAbandoned();
 
diff --git a/src/ui/qmlbackend.cpp b/src/ui/qmlbackend.cpp
index a75809ce..ebe45d1b 100644
--- a/src/ui/qmlbackend.cpp
+++ b/src/ui/qmlbackend.cpp
@@ -270,7 +270,7 @@ void QmlBackend::replyDelayTest(const QString &screenName,
   auto md5 = calcFileMD5();
 
   QJsonArray arr;
-  arr << screenName << cipher << md5 << FK_VERSION;
+  arr << screenName << cipher << md5 << FK_VERSION << GetDeviceUuid();
   ClientInstance->notifyServer("Setup", JsonArray2Bytes(arr));
 }