伊春区伊美区

Cannot delete an attribute that cannot be deleted, otherwise an error will be reportedSYN 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.202. X.X.240陈启写出一系列经典武侠、经典网络小说，忠实读者、粉丝无数，而郭寒也不容小觑，专注青春文学，苦心经营了这些年，在青少年中影响力非常大，铁杆粉丝也是极多。Principle: Traditional tobacco is smoked by ignition. The temperature of tobacco when burning reaches 800 degrees. Nicotine, carbon monoxide, tar, etc. will be produced in the process of tobacco burning. At the same time, tobacco itself also has fragrance released. Smokers are mainly satisfied by smoking nicotine and tobacco fragrance. There are more than 2,000 kinds of harmful ingredients produced by smoking, The main components that cause harm to human health come from tar produced in the combustion process, However, the working temperature of the heating non-burning electronic cigarette is about 300. Not more than 300 degrees, Tar is mainly produced at over 400 degrees, In other words, Heating does not burn electronic cigarettes. Due to the relationship between temperature, A small amount of tar is produced, which can be ignored. Moreover, the temperature at which heating does not burn is only about 300 degrees, so there is no combustion, no open flame and no soot. However, the aroma and smell of tobacco are still released, and smokers can also obtain nicotine, so that smokers can also obtain the feeling of smoking real cigarettes.只说初选结束，总共选了一百零八人。