Guacamole SSH断开连接，没有键盘

Question

我在客户端使用官方JavaScript代码在服务器端扩展0.9.12-incubating上使用Guacamole GuacamoleHTTPTunnelServlet。 Guacamole服务器是从源代码编译的，在Ubuntu 17.04上运行。

SSH连接已成功建立，但在15秒后断开连接。没有键盘敲击和鼠标工作。

May  7 17:14:09 dev guacd[4071]: Creating new client for protocol "ssh"
May  7 17:14:09 dev guacd[4071]: Connection ID is "$30e2e833-5640-4bc9-92c3-929ced3d6e0e"
May  7 17:14:09 dev guacd[4382]: User "@4209df46-e26a-4ced-93c4-c264578f85a5" joined connection "$30e2e833-5640-4bc9-92c3-929ced3d6e0e" (1 users now present)
May  7 17:14:10 dev guacd[4382]: SSH connection successful.
May  7 17:14:24 dev guacd[4382]: User is not responding.
May  7 17:14:24 dev guacd[4382]: User "@4209df46-e26a-4ced-93c4-c264578f85a5" disconnected (0 users remain)
May  7 17:14:24 dev guacd[4382]: Last user of connection "$30e2e833-5640-4bc9-92c3-929ced3d6e0e" disconnected
May  7 17:14:25 dev guacd[4382]: SSH connection ended.
May  7 17:14:25 dev guacd[4071]: Connection "$30e2e833-5640-4bc9-92c3-929ced3d6e0e" removed.

客户端JavaScript与文档中的相同 - https://guacamole.incubator.apache.org/doc/gug/writing-you-own-guacamole-app.html。

当我在servlet中使用Override方法时，它们会向我显示关键笔划。那么问题可能介于servlet和guacd之间？

@Override
protected void doWrite(HttpServletRequest request, HttpServletResponse response, String tunnelUUID) throws GuacamoleException {
        LOGGER.debug("Do WRITE to session " + tunnelUUID);
        super.doWrite(request, response, tunnelUUID);
    }

@Override
protected void doRead(HttpServletRequest request, HttpServletResponse response, String tunnelUUID) throws GuacamoleException {
        LOGGER.debug("Do read to session " + tunnelUUID);
        super.doRead(request, response, tunnelUUID);
    }

已建立连接，但没有按键操作：

感谢。