SYN attack is a kind of DOS attack. It takes advantage of TCP protocol defects and consumes CPU and memory resources by sending a large number of semi-connection requests. SYN attacks can not only affect hosts, but also harm network systems such as routers and firewalls. In fact, SYN attacks can be implemented as long as these systems turn on TCP services no matter what systems are targeted. As can be seen from the above figure, the server receives the connection request (syn=j), adds this information to the unconnected queue, and sends the request packet to the client (syn=k, ack=j+1), then enters the SYN_RECV state. When the server does not receive an acknowledgement packet from the client, it retransmits the request packet and does not delete this entry from the non-connection queue until the timeout. With IP spoofing, SYN attacks can achieve good results, Typically, clients forge a large number of non-existent IP addresses in a short period of time, SYN packets are continuously sent to the server, and the server replies to the confirmation packets and waits for the confirmation of the customer. Since the source address does not exist, the server needs to continuously resend until it timeout. These forged SYN packets will occupy the unconnected queue for a long time, normal SYN requests will be discarded, the target system will run slowly, and in serious cases, the network will be blocked or even the system will be paralyzed.天才少年古云，因为被上古神族中下神印，导致灵力减弱，成为青山门公认的废物，被贬为杂役。父亲因此被牵连，废除族长之位，囚禁在敌人飞卢家族的天牢里。这时古云发现了自己身上隐藏的秘密，并且跟古神达成合作协议。The House will end its vacation on Monday, which means that the death of Brexit will return to the theater authorities, which will not have a negative impact on capital markets such as sterling and gold. In addition, investors need to stop paying attention to the Sino-US World Trade Organization this week. Changes in consumer market anxiety will have the most important negative impact on the gold market. Pay close attention to the industry number "Xia Junshan" and learn more about foreign exchange reserves.Creative patterns are patterns used to create objects, abstracting the instantiation process. All creative patterns have two things in common. First, they all encapsulate the specific types of information used by the system. Second, they hide how instances of these classes are created and organized. Creative patterns include singleton patterns, factory method patterns, abstract factory patterns, builder patterns and prototype patterns.Public class User1 extensions User {影片讲述了一段东方罗密欧与朱丽叶式的爱情故事：青梅竹马的男孩侯嘉和女孩屈然，在少年时就彼此暗恋，但家庭间的仇恨却成为两人爱情间的一道荆棘。直到他们在无意间看到莎士比亚的《罗密欧与朱丽叶》，才给他们干涸的爱情带来了希望，燃烧的激情让他们无法控制汹涌的爱火，决定用绚烂的青春给他们的爱画上永恒的动人色彩…… 转眼间侯嘉（陆毅 饰）和屈然（赵薇饰）都18岁了，这是80年代初期。侯嘉和屈然每天一起上学、放学，爱情就在他们不知不觉中悄悄的来临。但他们万万没想到的是这份青梅竹马的爱情竟然会遭到两家父母的强烈反对，就像一道无法跨越的荆棘横在了他们的爱情面前。往前一步就会弄得大家遍体鳞伤，退后一些又会彼此舍不得。直到他们偶然读了莎士比亚的《罗密欧与朱丽叶》，他们决定要坚持，但这份坚持没多久就被亲情的束缚打败了……Tang Lin, producer of CCTV's financial channel "Charming China City", Reveals Innovative Highlights of the Second Season's Purpose: First, the timing of the second season of the program is better than that of the first season. The 19th National Congress and the National Two Sessions have been held one after another. At the same time, the 40th anniversary of reform and opening-up is a great moment. From the perspective of the country, we can see the pace of our city and the pace of China. Second, humanistic care is more intense. We only do two rounds of competition, so that the city can focus on the program and carry out intensive cultivation, so that the charm of the city can be better released. Third, we should use real elements to express our love for the city. We will follow the process of filming all the city competitions and rehearsals, and aspire to set up a biography for each city. Competition is only a means, reality is the end.
