无人区高清图

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.3.1刑警我妻谅介一向奉行以暴制暴的原则，由于其凶暴的行事风格，他在警察局里被视为异端。毒贩子柄本被杀，我妻负责侦破此案。年轻的菊地是我妻的搭档，两人却根本合不来。我妻追查到了青年实业家仁藤以及杀手清弘与此事有关，却不料他的同事兼好友岩城正是这个贩毒网在警察局的内线。Illustration of Event Delivery MechanismThat's horrible! ! ! ! ! It's really terrible! ! ! ! ! !是大苞谷，他昂然走进来，后面跟着山芋众兄弟。