基于 Raw Socket 的 数据包捕获程序。支持 TCP/UDP/ICMP,支持端口及IP 过滤。-Raw Socket-based packet data capture process. Supports TCP / UDP / ICMP, IP and port support filtering.

create raw socket for icmp protocol and drop root privileges if running setuid.

UDP扫描原理与TCP扫描原理不同，UDP扫描是通过向对方UDP端口发送数据，然后根据对方ICMP返回数据进行判断。接收ICMP数据包只能采用RAW Socket接收到所有的数据包，然后从中过滤出哪一个数据包是对方返回的，进而判断出对方端口是否处于开状态。-UDP scanning principle and TCP scanning works differently, UDP port scans are sent via UDP to the other data, and then re

编写一个简单的 ping 程序。利用 Raw Socket 封装和发送以太网帧的功能，实现 ICMP 包的发送和接收，并输出结果。(Write a simple ping program. Using Raw Socket encapsulation and send Ethernet frame function, to achieve ICMP packet sending and receiving, and output the results.)

基于RAW套接字的ICMP协议ping功能源码，linux平台验证通过。(Based on RAW socket's ICMP protocol ping function source, Linux platform verification is adopted.)