链接：https://www.pixelstech.net/article/1514049471-Check-whether-a-remote-server-port-is-open-on-Linux
链接：https://www.pixelstech.net/article/1514049471-Check-whether-a-remote-server-port-is-open-on-Linux
Check whether a remote server port is open on Linux
原文：http://www.cnblogs.com/echo1937/p/8107888.html