国精产品少女

Public String getName () {杀东方不败翻到《问卜》那一篇，让他们看。死神，很多人以为他拿着镰刀，面目狰狞，甚至有人以为他有一本笔记本，决定人的生死…但有否想过，死神，可能只是一些普通人，他们没有法力，与你我无异，他们只是一群人，一个机构，默默地在执行着死亡任务。In TCP implementation, when receiving the SYN request from the client, the server needs to reply the SYN + ACK packet to the client, and the client also needs to send the confirmation packet to the server. Usually, the initial serial number of the server is calculated by the server according to certain rules or adopts random numbers. However, in SYN cookies, the initial serial number of the server is obtained by hash operation and encryption of the client IP address, client port, server IP address, server port and other security values, which is called cookie. When the server suffers from SYN attack and makes the backlog queue full, the server does not reject the new SYN request, but replies the cookie (SYN serial number of the reply packet) to the client. If it receives the ACK packet from the client, the server subtracts 1 from the ACK serial number of the client to obtain the cookie comparison value, and performs a hash operation on the above elements to see if it is equal to the cookie. If equal, complete the three-way handshake directly (Note: At this time, you don't need to check whether this connection belongs to the backlog queue).Let's take a picture first to see the relationship between these 11 modes: