src/main/java/com/groupon/mesos/util/NetworkUtil.java
public static int findUnusedPort() throws IOException
    {
        int port;

        try (ServerSocket socket = new ServerSocket()) {
            socket.bind(new InetSocketAddress(0));
            port = socket.getLocalPort();
        }

        return port;
    }
public static int findUnusedPort() throws IOException
    {
        int port;

        try (ServerSocket socket = new ServerSocket()) {
            socket.bind(new InetSocketAddress(0));
            port = socket.getLocalPort();
        }

        return port;
    }
Find an unused port.