@Override
    int getIp() {
        return 0;
    }
The UDP proxy server is a virtual server, every packet from {@link UdpProxyServerForwarder} is
saw as a connection. It use {@link UdpVATunnel} to bind {@link VirtualGateway} and
{@link NioTunnel} together. Not like TCP, UDP only use {@link UdpRemoteTunnel} to communicate with
real remote server.

@author Megatron King
@since 2018-10-11 17:35
netbare-core/src/main/java/com/github/megatronking/netbare/proxy/UdpProxyServer.java