possible SYN flooding on ctid 42131, port 80. Sending cookies. - Solution -

possible SYN flooding on ctid 42131, port 80. Sending cookies. - Solution

The Linux Kernel interpretated a very high volume of real traffic as a DDOS attack so it basically ends up blocking your web server.

possible SYN flooding on ctid 42131, port 80. Sending cookies.

Simple fix edit sysctl values for max_syn_backlog
sysctl -w net.ipv4.tcp_max_syn_backlog=5000


To make them permanent edit /etc/sysctl.conf

echo "net.ipv4.tcp_max_syn_backlog=5000" >> /etc/sysctl.conf


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