ipHeader.ttl = 128; 　ipHeader.proto = IPPROTO_TCP; 　ipHeader.checksum = 0; 　ipHeader.sourceIP = inet_addr("localhost"); 　ipHeader.destIP = desIP; 　//填充TCP报头 　tcpHeader.th_dport = htons(desPort); 　tcpHeader.th_sport = htons(SOURCE_PORT); //源端口号 　tcpHeader.th_seq = htonl(0x12345678); 　tcpHeader.th_ack = 0; 　tcpHeader.th_lenres = (sizeof(tcpHeader) / 4 << 4 | 0); 　tcpHeader.th_flag = 2; //标志位探测，2是SYN 　tcpHeader.th_win = htons(512); 　tcpHeader.th_urp = 0; 　tcpHeader.th_sum = 0; 　psdHeader.saddr = ipHeader.sourceIP; 　psdHeader.daddr = ipHeader.destIP; 　psdHeader.mbz = 0; 　psdHeader.ptcl = IPPROTO_TCP; 　psdHeader.tcpl = htons(sizeof(tcpHeader)); 　//计算校验和 　memcpy(szSendBuf, &psdHeader, sizeof(psdHeader)); 　memcpy(szSendBuf + sizeof(psdHeader), &tcpHeader, sizeof(tcpHeader)); 　tcpHeader.th_sum = checksum((unsigned short*)szSendBuf, sizeof(psdHeader) + sizeof(tcpHeader)); 　 　memcpy(szSendBuf, &ipHeader, sizeof(ipHeader)); 　memcpy(szSendBuf + sizeof(ipHeader), &tcpHeader, sizeof(tcpHeader)); 　memset(szSendBuf + sizeof(ipHeader) + sizeof(tcpHeader), 0, 4); 　ipHeader.checksum = checksum((unsigned short*)szSendBuf, sizeof(ipHeader) + sizeof(tcpHeader)); 　memcpy(szSendBuf, &ipHeader, sizeof(ipHeader)); 　rect = sendto(sock, szSendBuf, sizeof(ipHeader) + sizeof(tcpHeader), 0, (struct sockaddr*) &addr_in, sizeof(addr_in)); 　if (rect == SOCKET_ERROR) 　{ 　　printf("send error!:%d\n", WSAGetLastError()); 　　return false; 　} 　else 　　printf("send ok!\n"); 　closesocket(sock); 　WSACleanup(); 　return rect; }

　　(参考链接: http://dev.yesky.com/80/2663580.shtml)