我故意没有穿内裤坐公车让

A class has only one instance and instantiates itself and provides this instance to the entire system.小葱急忙道：娘。郑长河对黄豆夸道：我孙子就是脑瓜子灵光。小葱张张嘴，却不知如何说起，隐约一点猜测，让她觉得胸口闭闷难受。860010-1107020600In addition to solving the port problem of A, the serial number problem also needs to be paid attention to. The serial number corresponds to the sliding window. The fake TCP packet needs to be filled with the serial number. If the value of the serial number is not in the sliding window of B when it is sent to B before A, B will actively discard it. So we need to find the serial number that can fall into the sliding window between AB at that time. This can be solved violently, because the length of a sequence is 32 bits, and the value range is 0-4294967296. If the window size is like 65535 under Windows I caught in the above figure, I only need to divide, and I know that at most I only need to send 65537 (4294967296/65535=65537) packets to have a sequence number fall into the sliding window. The desired value can be calculated quickly by exhaustion on multiple control hosts.