Anti-DDOS in Linux

Squid also uses the port ing function to convert port 80. In fact, common DDOS attacks can modify the parameters in/proc/sys/net/ipv4/tcp_max_syn_backlog, the default parameters are usually very small and set to more than 8000. Generally, DDOS attacks can be solved. If it reaches the timeout stage, set/proc/sys/net/ipv4/tcp_fin_timeout to a smaller value.

Everyone is discussing DDOS. I personally think there is no real solution at present. I just want to expand the buffer and defense capabilities and play a psychological tactic with hackers to see who sticks to the end, there are also many practices on the Internet, such as syncookies, which are complex points.

Sysctl-w net. ipv4.icmp _ echo_ignore_all = 1
Echo 1>/proc/sys/net/ipv4/tcp_syncookies
Sysctl-w net. ipv4.tcp _ max_syn_backlog = "2048"
Sysctl-w net. ipv4.tcp _ synack_retries = "3"

Iptables-a input-I eth0-p tcp -- syn-j syn-flood
# Limit 12 connections per second (burst to 24)
Iptables-A syn-flood-m limit -- limit 12/s -- limit-burst 24-j RETURN
In this case, you can try:
Iptbales-a forward-p tcp -- syn-m limit -- limit 1/s-j ACCEPT