--- a/src/main/java/com/glavsoft/rfb/encoding/decoder/ZRLEESender.java	Sun Feb 16 18:26:03 2020 +0900
+++ b/src/main/java/com/glavsoft/rfb/encoding/decoder/ZRLEESender.java	Mon Feb 17 01:03:25 2020 +0900
@@ -56,13 +56,8 @@
                 return;
             }
         }
-        if (rfb.multicastBlocking) {
-            ZRLEDecoder decoder = new ZRLEDecoder();
-            decoder.multicastDecode(reader, renderer, rect, rfb);
-        } else {
-            byte[] bytes = new byte[rect.width * rect.height * renderer.getBytesPerPixel()];
-            rfb.readSendData(dataLen, reader, bytes, rect);
-        }
+        byte[] bytes = new byte[rect.width * rect.height * renderer.getBytesPerPixel()];
+        rfb.readSendData(dataLen, reader, bytes, rect);
     }
 
     private int getZrleLength(FramebufferUpdateRectangle rect, Reader reader)

--- a/src/main/java/com/glavsoft/rfb/protocol/ReceiverTask.java	Sun Feb 16 18:26:03 2020 +0900
+++ b/src/main/java/com/glavsoft/rfb/protocol/ReceiverTask.java	Mon Feb 17 01:03:25 2020 +0900
@@ -250,7 +250,7 @@
             numberOfRectangles = reader.readUInt16();
             this.numberOfRectangles = numberOfRectangles;
             if(numberOfRectangles > 3) {
-                System.out.println("numberofrectangle : " + numberOfRectangles);
+                // System.out.println("numberofrectangle : " + numberOfRectangles);
                 if (rfb.getViewer().getUseMulticast()){
                     return; // Discard invalid packet
                 }
@@ -288,14 +288,11 @@
                         int width = reader.readUInt16();
                         int height = reader.readUInt16();
                         long flag = reader.readUInt32();
-
-
                         FramebufferUpdateRectangle screen = new FramebufferUpdateRectangle(x, y, width, height);
                         screen.port = (int) id;
                         screen.time = flag;
                         screens.add(screen);
                         System.out.println("screen " + id + ":" + "x=" + x + " y=" + y + "width=" + width + "height=" + height);
-
                     }
                     return;
                 } else if (rect.getEncodingType() == EncodingType.DESKTOP_SIZE) {
@@ -379,7 +376,7 @@
         Reader in = new Reader(new ByteArrayInputStream(c1.array()));
         try {
             if (getMessageId(in) != FRAMEBUFFER_UPDATE) {
-                ;
+                return;
             }
             in.readByte();
             int numberOfRectangeles = in.readInt16();
@@ -426,6 +423,31 @@
         }
     }
 
+    public void handleMulticastFrameBufferUpdate(ByteBuffer c1) {
+        FramebufferUpdateRectangle rect = new FramebufferUpdateRectangle();
+        Reader in = new Reader(new ByteArrayInputStream(c1.array()));
+        try {
+            if (getMessageId(in) != FRAMEBUFFER_UPDATE) {
+                return;
+            }
+            in.readByte();
+            int numberOfRectangeles = in.readInt16();
+            ZRLEDecoder zdecoder = new ZRLEDecoder();
+            Decoder decoder = zdecoder;
+            while (numberOfRectangeles-- > 0) {
+                rect.fill(in);
+                if (rect.getEncodingType() == EncodingType.ZRLEE) {
+                    System.out.println();
+                    decoder.decode(in,renderer,rect);
+                    if (rfb.getCuiVersion()) continue;
+                    repaintController.repaintBitmap(rect);
+                }
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+        }
+    }
+
     private void compareBytes(ByteBuffer buf, byte[] bytes, int flushOffset, int flushEnd) {
         int span = flushEnd - flushOffset;
         int pos = buf.position();

--- a/src/main/java/jp/ac/u_ryukyu/treevnc/BroadcastRFBListener.java	Sun Feb 16 18:26:03 2020 +0900
+++ b/src/main/java/jp/ac/u_ryukyu/treevnc/BroadcastRFBListener.java	Mon Feb 17 01:03:25 2020 +0900
@@ -51,8 +51,9 @@
     }
 
     /**
-	 * To find TreeVNC root, a client sends me a multicast, reply our address to him.
-	 *  It contains a port to receive, so multiple TREEVNC clients can run on a PC. 
+	 * Accept multicast framebufferupdate
+	 *    we should accept only from acceptable server
+	 *    some kind of signature
 	 */
 	private void rfbBroadcastLoop() {
 		while (!stopFlag) {
@@ -60,14 +61,11 @@
 				byte[] buf = new byte[BufSize];
 				DatagramPacket recvPacket = new DatagramPacket(buf, BufSize);
 				soc.receive(recvPacket);
-				String hostname = recvPacket.getAddress().getHostAddress();
+				// String hostname = recvPacket.getAddress().getHostAddress();
 				byte[] reply = recvPacket.getData();
-				int len = recvPacket.getLength();
-				boolean isTreeRoot = rfb.isTreeManager();
 				if (receiverTask != null) {
-					Reader reader = new Reader(new ByteArrayInputStream(reply));
-					if (receiverTask.getMessageId(reader) == FRAMEBUFFER_UPDATE) {
-						receiverTask.framebufferUpdateMessage(reader);
+					if (reply[0] == FRAMEBUFFER_UPDATE) {
+						receiverTask.handleMulticastFrameBufferUpdate(ByteBuffer.wrap(reply));
 					}
 				}
 			} catch (Exception e) {