setsockopt(rcv_sock, SOL_SOCKET, SO_RCVTIMEO, &read_timeout, sizeof(read_timeout));
    for (int i = low_port; i <= high_port; i++)
    {
        tmp_msg.clear();
        udph->check = 0;
        memset (datagram2, 0, 4096);
        // Set destination port in UDP header
        udph->dest = htons (i);
        to.sin_port = htons(i);
        memset(pseudogram, 0, psize);
        memcpy(pseudogram , (char*) &psh , sizeof (struct pseudo_header));
        memcpy(pseudogram + sizeof(struct pseudo_header) , udph , sizeof(struct udphdr) + strlen(data));

        udph->check = csum( (unsigned short*) pseudogram , psize);
        //std::cout << udph->check << std::endl;

        if (sendto (sock, datagram, iph->tot_len,  0, (struct sockaddr *) &to, sizeof(to)) < 0)
        {
            perror("sendto failed");
        }
        usleep(1000);
        rcvd_l = recvfrom(rcv_sock, datagram2, sizeof(datagram2),  0, (struct sockaddr *) &to, &addrlen);
        if(datagram2[0] != 0){
            std::cout << "port: " << i << std::endl;
            std::cout << "recieved length: " << rcvd_l << std::endl;
            int counter = 0;
            for (int j = sizeof(struct iphdr) + sizeof(struct udphdr); j < rcvd_l; j++) {
                std::cout << datagram2[j];
                tmp_msg += datagram2[j];
                counter++;
            }
            if (tmp_msg.find("61453") != std::string::npos) {
                chcksum_port = i;
                std::cout << "checksum port: " << chcksum_port << std::endl;
            }
            std::cout << std::endl << std::endl;
        }
    }