diff --git a/src/de/steamwar/bungeecore/BungeeCore.java b/src/de/steamwar/bungeecore/BungeeCore.java
index b0c69b61..ea959b73 100644
--- a/src/de/steamwar/bungeecore/BungeeCore.java
+++ b/src/de/steamwar/bungeecore/BungeeCore.java
@@ -28,7 +28,10 @@ import de.steamwar.bungeecore.listeners.ping.PingListener;
 import de.steamwar.bungeecore.network.BungeeNetworkHandler;
 import de.steamwar.bungeecore.network.NetworkReceiver;
 import de.steamwar.bungeecore.network.SWScriptSyntaxForwarder;
-import de.steamwar.bungeecore.sql.*;
+import de.steamwar.bungeecore.sql.Punishment;
+import de.steamwar.bungeecore.sql.SteamwarUser;
+import de.steamwar.bungeecore.sql.Team;
+import de.steamwar.bungeecore.sql.UserElo;
 import de.steamwar.bungeecore.tablist.TablistManager;
 import de.steamwar.command.SWCommandUtils;
 import de.steamwar.command.SWTypeMapperCreator;
@@ -102,6 +105,8 @@ public class BungeeCore extends Plugin {
         });
         BungeeCord.getInstance().getScheduler().schedule(this, TabCompletionCache::invalidateOldEntries, 1, 1, TimeUnit.SECONDS);
 
+        new NonFabricFabricCheck();
+
         new SWScriptSyntaxForwarder();
         new ConnectionListener();
         new Forge();
diff --git a/src/de/steamwar/bungeecore/listeners/NonFabricFabricCheck.java b/src/de/steamwar/bungeecore/listeners/NonFabricFabricCheck.java
new file mode 100644
index 00000000..b903b9c2
--- /dev/null
+++ b/src/de/steamwar/bungeecore/listeners/NonFabricFabricCheck.java
@@ -0,0 +1,86 @@
+/*
+ * This file is a part of the SteamWar software.
+ *
+ * Copyright (C) 2022  SteamWar.de-Serverteam
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.steamwar.bungeecore.listeners;
+
+import de.steamwar.bungeecore.BungeeCore;
+import de.steamwar.bungeecore.Message;
+import de.steamwar.bungeecore.Storage;
+import net.md_5.bungee.BungeeCord;
+import net.md_5.bungee.api.connection.Connection;
+import net.md_5.bungee.api.connection.ProxiedPlayer;
+import net.md_5.bungee.api.event.LoginEvent;
+import net.md_5.bungee.api.event.PlayerDisconnectEvent;
+import net.md_5.bungee.api.event.PluginMessageEvent;
+import net.md_5.bungee.event.EventHandler;
+
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.Set;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+public class NonFabricFabricCheck extends BasicListener {
+
+    private final Set<UUID> usingFabric = new HashSet<>();
+
+    private final Set<ProxiedPlayer> checking = new HashSet<>();
+
+    {
+        BungeeCord.getInstance().getScheduler().schedule(BungeeCore.get(), usingFabric::clear, 0, 15, TimeUnit.MINUTES);
+    }
+
+    @EventHandler
+    public void pluginMessageEvent(PluginMessageEvent e) {
+        Connection sender = e.getSender();
+        if(!(sender instanceof ProxiedPlayer))
+            return;
+
+        if(!e.getTag().equals("minecraft:brand"))
+            return;
+
+        if(!new String(e.getData()).equals("vanilla")){
+            return;
+        }
+
+        ProxiedPlayer p = (ProxiedPlayer) sender;
+
+        BungeeCord.getInstance().getScheduler().schedule(BungeeCore.get(), () -> {
+            if (!p.isConnected()) return;
+            if (Storage.fabricCheckedPlayers.containsKey(p)) return;
+            checking.add(p);
+            p.sendData("fabric-screen-handler-api-v1:open_screen", new byte[] {0});
+            BungeeCord.getInstance().getScheduler().schedule(BungeeCore.get(), () -> checking.remove(p), 1, TimeUnit.SECONDS);
+        }, 30, TimeUnit.SECONDS);
+    }
+
+    @EventHandler
+    public void onPlayerPreLogin(LoginEvent e) {
+        if (usingFabric.remove(e.getConnection().getUniqueId())) {
+            e.getConnection().disconnect(Message.parse("MOD_USE_MODSENDER", Locale.getDefault()));
+        }
+    }
+
+    @EventHandler
+    public void onPlayerDisconnect(PlayerDisconnectEvent e) {
+        if (checking.remove(e.getPlayer())) {
+            usingFabric.add(e.getPlayer().getUniqueId());
+        }
+    }
+}
diff --git a/src/de/steamwar/messages/BungeeCore.properties b/src/de/steamwar/messages/BungeeCore.properties
index fb44d5a8..b4256b25 100644
--- a/src/de/steamwar/messages/BungeeCore.properties
+++ b/src/de/steamwar/messages/BungeeCore.properties
@@ -116,6 +116,8 @@ MOD_RED_PLUR=Attempted use of mods:\n{0}
 MOD_YELLOW_SING=§7Deactivate the mod §e{0}§7 to continue playing on §eSteam§8War§7.
 MOD_YELLOW_PLUR=§7Deactivate the mods\n§e{0}\n§7to continue playing on §eSteam§8War§7.
 
+MOD_USE_MODSENDER=§cPlease use the §c§lFabricModSender§c (https://steamwar.de/downloads/) or remove the mod that is rebranding your installation.
+
 #Various commands
 ALERT=§f{0}
 STAT_SERVER=§7Server §e{0}§8: §7Below limit §e{1} §7Server count §e{2}
diff --git a/src/de/steamwar/messages/BungeeCore_de.properties b/src/de/steamwar/messages/BungeeCore_de.properties
index f9b11af6..83de9f61 100644
--- a/src/de/steamwar/messages/BungeeCore_de.properties
+++ b/src/de/steamwar/messages/BungeeCore_de.properties
@@ -102,6 +102,8 @@ MOD_RED_PLUR=Versuchte Benutzung der Mods:\n{0}
 MOD_YELLOW_SING=§7Deaktiviere den Mod §e{0}§7, um weiter auf §eSteam§8War §7spielen zu können.
 MOD_YELLOW_PLUR=§7Deaktiviere die Mods\n§e{0}\n§7um weiter auf §eSteam§8War §7spielen zu können.
 
+MOD_USE_MODSENDER=§cBitte nutze den §c§lFabricModSender§c (https://steamwar.de/downloads/) oder entfernen den Mod, der die Installation umbenennt.
+
 #Various commands
 STAT_SERVER=§7Server §e{0}§8: §7Startfähig §e{1} §7Serveranzahl §e{2}