ssyn

Bus Operation Sequence and operation mode operation sequence (timing): Effective sequence and cooperation relationship of each signal (1) Synchronous Mode• Sending and receiving are at a unified pace, with a unified clock signal.• The synchronous clock determines the sending and receiving time completely without a response signal.• Example: Bus read Operations(2) asynchronous mode• The sender and receiver determine the speed at which the bus is transmitted based on their working speed• No unifie

Common usage (sudo is used here because the current account does not have the permission to use tcpdump. here we only use a tcp example to describe it ): sudo/usr/sbin/tcpdumptcpport80andhost172.23.1.69-each row of the ieth1-n carries the flag in the middle of the package: SSYN, initiate the connection flag PPUSH, transfer the data flag FFIN, close the connection flag ack table Common usage (sudo is used here because the current account is not authori

For several links of Syn attack, the corresponding processing methods are proposed:Mode 1: Reduce the number of Syn-ack packets (default is 5): sysctl-w net.ipv4.tcp_synack_retries=3 sysctl -w net.ipv4.tcp_syn_retries=3 Method 2: Use SYN Cookie technology: sysctl -w net.ipv4.tcp_syncookies=1 Mode 3: Increase the backlog queue (default is 1024): sysctl -w net.ipv4.tcp_max_syn_backlog=2048 Method 4: Limit the number of SYN concurren

processed normally. SYN Attack Processing The following solutions are provided for SYN Attacks: Method 1: Reduce the number of retransmissions of SYN-ACK packets (5 by default ): sysctl -w net.ipv4.tcp_synack_retries=3 sysctl -w net.ipv4.tcp_syn_retries=3 Method 2: Use SYN Cookie technology:sysctl -w net.ipv4.tcp_syncookies=1 Method 3: Add a backlog Queue (default value: 1024 ):sysctl -w net.ipv4.tcp_max_syn_backlog=2048 Method 4: Limit the number of SYN concurrent connections:iptables -A INPU

attack, the corresponding processing methods are proposed:Mode 1: Reduce the number of Syn-ack packets (default is 5):Method 2: Use SYN Cookie technology:Mode 3: Increase the backlog queue (default is 1024):Method 4: Limit the number of SYN concurrency:Iptables-a input-p tcp--syn-m limit--limit 1/s-j ACCEPT--limit 1/sSYN Attack simulation You can use the Hping tool described earlier to simulate SYN attacks, see Linux Common Network Tools: hping