#include <sys/types.h>#include<sys/stat.h>#include<fcntl.h>#include<unistd.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#define PORT 2345 /*使用的port*/main(){int sockfd,len;struct sockaddr_in addr;int addr_len =sizeof(struct sockaddr_in);char buffer[256];/*建立socket*/if(sockfd=socket(AF_INET,SOCK_DGRAM,0)<0){perror ("socket");exit(1);}/*填寫sockaddr_in 結(jié)構(gòu)*/bzero(&addr, sizeof(addr));addr.sin_family=AF_INET;addr.sin_port=htons(PORT);addr.sin_addr  = htonl(INADDR_ANY);if(bind(sockfd, &addr, sizeof(addr))<0){perror("connect");exit(1);}while(1){bezro(buffer,sizeof(buffer));len = recvfrom(socket,buffer,sizeof(buffer), 0 ,&addr,&addr_len);/*顯示client端的網(wǎng)絡(luò)地址*/printf("receive from %s\n ",inet_ntoa(addr.sin_addr));/*將字串返回給client端*/sendto(sockfd,buffer,len,0,&addr,addr_len);}}