,(SA *)&server,sizeof(SA_IN));
send(sockfd,&s,sizeof(char),0);
recv(sockfd,&ip,sizeof(IP),0);...close(sockfd);
sockfd2=socket(AF_INET,SOCK_STREAM,0);
if(sockfd2 == -1)
perror...(sockfd2,(SA *)&server,sizeof(SA_IN)) == -1)
perror("bind sockfd");
if(listen(sockfd2,20) ==...,(SA *)&server,sizeof(SA_IN));
recv(sockfd,&ip,sizeof(IP),0);
close(sockfd);
sockfd2...(sockfd2);
return 0;
}