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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).The signal attenuation of 100 meters cable is the same. Therefore, the influence and effect of temperature on signal attenuation is far greater than many other fixed factors.周夫子沉吟了一下，点头道：由得你。关中的富足与独特地理位置，还有关中是秦王朝的发祥地，代表了非同一般的政治象征意义。Some car air conditioners will overflow with peculiar smell as soon as they are turned on, which is unbearable. I believe many car owners have encountered the phenomenon of peculiar smell in car air conditioners. How does the car air conditioner produce peculiar smell?