一 代码
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/if_packet.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <unistd.h> //for close
typedef struct _iphdr //定义IP首部
{
unsigned char h_verlen; //4位首部长度+4位IP版本号
unsigned char tos; //8位服务类型TOS
unsigned short total_len; //16位总长度(字节)
unsigned short ident; //16位标识
unsigned short frag_and_flags; //3位标志位和13位片偏移
unsigned char ttl; //8位生存时间 TTL
unsigned char proto; //8位协议 (TCP, UDP 或其他)
unsigned short checksum; //16位IP首部校验和
unsigned int sourceIP; //32位源IP地址
unsigned int destIP; //32位目的IP地址
}IP_HEADER;
typedef struct _udphdr //定义UDP首部
{
unsigned short uh_sport; //16位源端口
unsigned short uh_dport; //16位目的端口
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