How to check if remote UDP port is open? C [duplicate]
可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效,请关闭广告屏蔽插件后再试): 问题: This question already has an answer here: Checking open UDP Port in C++ 2 answers It's easy to test for TCP, but how about UDP? Here: Check if OpenVPN UDP Port is open I read that it is impossible to do this. However, here: How to retrieve both TCP and UDP ports with Nmap? it was proved that nmap can do this, so its possible I think. I wrote a very simple code: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include