Close client connection in Netty

Question

I have simple Netty client/server app. in server side I check if client connect from right host or not and if it's not correct, close the client's connection. in server side I use this code:

@Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {

        String remoteAddress = ctx.channel().remoteAddress().toString();
        if(!"/127.0.0.1:42477".equals(remoteAddress)) {
            ctx.writeAndFlush("Not correct remote address! Connection closed");
            ctx.close();
        }
        System.out.println(remoteAddress);
    }

and in client side this one:

@Override
    protected void channelRead0(ChannelHandlerContext ctx, String data) throws Exception {
        try {
            System.err.println(data);
        } finally {
            ReferenceCountUtil.retain(data);
        }       
    }

but I can't get the message from server side in ctx.writeAndFlush() and client side shutdown with exception:

java.io.IOException: Соединение сброшено другой стороной(TRANSLATION: Connection reset from the other side)
    at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
    at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
    at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
    at sun.nio.ch.IOUtil.read(IOUtil.java:192)
    at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:379)
    at io.netty.buffer.UnpooledUnsafeDirectByteBuf.setBytes(UnpooledUnsafeDirectByteBuf.java:447)
    at io.netty.buffer.AbstractByteBuf.writeBytes(AbstractByteBuf.java:881)
    at io.netty.channel.socket.nio.NioSocketChannel.doReadBytes(NioSocketChannel.java:242)
    at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:119)
    at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:511)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:468)
    at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:382)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:354)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:111)
    at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)
    at java.lang.Thread.run(Thread.java:745)

how I can close client connection in rigth way? I'm newbe in netty

Solution

ctx.writeAndFlush is asynchronous and therefore may return before the data is actually written to the channel. However, it returns a ChannelFuture, which lets you add a listener which will be notified when the operation is complete. To make sure the channel is closed only after the data has been written, you can do the following:

ctx.writeAndFlush("Not correct remote address! Connection closed")
        .addListener(ChannelFutureListener.CLOSE);