- dlna monitor *
通过监听组播获得dlna设备的服务端口
然后调用tcpdump对dlna设备的服务端口进行抓包，打印出包头，找出到底是谁投了我的屏幕。
支持同局域网的多个dlna设备
依赖tcpdump，可能需要开网卡混杂模式。
实例输出
start to listen muticast
tcpdump waiting for massage
tcpdump tcp and ((dst 192.168.0.175 and port 49152))
listening on br-lan, link-type EN10MB (Ethernet), capture size 262144 bytes
23:43:47.846839 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.850176 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.850672 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.853555 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.853818 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.853876 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:43:47.854787 IP 192.168.0.174.38608 > 192.168.0.175.49152:
23:44:47.875943 IP 192.168.0.174.41120 > 192.168.0.175.49152:
23:44:47.878182 IP 192.168.0.174.41120 > 192.168.0.175.49152:
23:44:47.879667 IP 192.168.0.174.41120 > 192.168.0.175.49152:
23:44:47.884485 IP 192.168.0.174.41120 > 192.168.0.175.49152:
23:44:47.884612 IP 192.168.0.174.41120 > 192.168.0.175.49152:
23:44:47.884641 IP 192.168.0.174.41120 > 192.168.0.175.49152:
我就不信揪不出来你