diff --git a/src/main/java/xyz/nifeather/morph/network/server/MorphClientHandler.java b/src/main/java/xyz/nifeather/morph/network/server/MorphClientHandler.java
index dd9efa5e..68aab559 100644
--- a/src/main/java/xyz/nifeather/morph/network/server/MorphClientHandler.java
+++ b/src/main/java/xyz/nifeather/morph/network/server/MorphClientHandler.java
@@ -151,6 +151,9 @@ private void logPacket(boolean isOutGoingPacket, Player player, String channel,
     private final CommandRegistries registries = new CommandRegistries();
     private final Bindable<Boolean> modifyBoundingBoxes = new Bindable<>(false);
     private final Bindable<Boolean> useClientRenderer = new Bindable<>(false);
+    private final Bindable<Boolean> debugOutput = new Bindable<>(false);
+
+    private static final String newProtocolIdentify = "1_21_3_packetbuf";
 
     @Initializer
     private void load(MorphPlugin plugin, MorphConfigManager configManager)
@@ -176,9 +179,37 @@ private void load(MorphPlugin plugin, MorphConfigManager configManager)
             if (logInComingPackets.get())
                 logPacket(false, player, initializeChannel, data);
 
+            try
+            {
+                var buffer = new FriendlyByteBuf(Unpooled.wrappedBuffer(data));
+
+                var utfData = Arrays.stream(buffer.readUtf().split(" ")).toList();
+                if (utfData.stream().noneMatch(s -> s.equals(newProtocolIdentify)))
+                {
+                    logger.info("'%s' is using a legacy client, which is not supported by now。".formatted(player.getName()));
+                    rejectPlayer(player);
+                    return;
+                }
+
+                buffer.clear();
+            }
+            catch (Throwable t)
+            {
+                logger.info("'%s' is using a legacy client, which is not supported by now。".formatted(player.getName()));
+
+                if (debugOutput.get())
+                {
+                    logger.info("Unable to decode packet. Is '%s' using a legacy client? %s".formatted(player.getName(), t.getMessage()));
+                    t.printStackTrace();
+                }
+
+                rejectPlayer(player);
+                return;
+            }
+
             playerConnectionStates.put(player, InitializeState.HANDSHAKE);
 
-            this.sendPacket(initializeChannel, player, "");
+            this.sendPacket(initializeChannel, player, newProtocolIdentify);
         });
 
         // 注册api频道处理
@@ -330,6 +361,8 @@ private void load(MorphPlugin plugin, MorphConfigManager configManager)
 
         configManager.bind(useClientRenderer, ConfigOption.USE_CLIENT_RENDERER);
 
+        configManager.bind(debugOutput, ConfigOption.DEBUG_OUTPUT);
+
         modifyBoundingBoxes.onValueChanged((o, n) ->
         {
             var players = Bukkit.getOnlinePlayers();
diff --git a/src/main/resources/assets/feathermorph/lang/en_us.json b/src/main/resources/assets/feathermorph/lang/en_us.json
index 8a5aad66..1b1b0fe1 100644
--- a/src/main/resources/assets/feathermorph/lang/en_us.json
+++ b/src/main/resources/assets/feathermorph/lang/en_us.json
@@ -135,6 +135,7 @@
   "hint.skill_hint": "Hint: You can activate skills by using <item> while sneaking",
   "hint.skill_hint_client": "Hint: Press <key:key.morphclient.skill> to activate disguise skill",
   "morph.client_version_mismatch": "<color:red>Client mod version mismatch, not activating enhanced features!",
+  "morph.unsupported_client_behavior": "Detected unsupported client behavior, not activating enhanced features!",
   "morph.client_version_mismatch_kick": "<color:red>Client mod version mismatch",
   "morph.cooling_down": "<color:red>Please wait before disguising again",
   "morph.disguise_banned_or_not_supported": "<color:red>This disguise is not supported or disabled by server",
diff --git a/src/main/resources/assets/feathermorph/lang/zh_cn.json b/src/main/resources/assets/feathermorph/lang/zh_cn.json
index 55f64996..88e91564 100644
--- a/src/main/resources/assets/feathermorph/lang/zh_cn.json
+++ b/src/main/resources/assets/feathermorph/lang/zh_cn.json
@@ -135,6 +135,7 @@
   "hint.skill_hint" : "小提示: 手持<item>下蹲使用可以激活当前伪装的主动技能",
   "hint.skill_hint_client" : "小提示：按下<key:key.morphclient.skill>键可以激活当前伪装的主动技能",
   "morph.client_version_mismatch" : "<color:red>客户端模组版本不匹配，将不会启用增强功能！",
+  "morph.unsupported_client_behavior": "<color:red>检测到不支持的客户端行为，将不会启用增强功能！",
   "morph.client_version_mismatch_kick" : "<color:red>客户端模组版本不匹配",
   "morph.cooling_down" : "<color:red>请等一会再进行伪装",
   "morph.disguise_banned_or_not_supported" : "<color:red>服务器不支持或已禁用此伪装",