[CentOS] database node / possible SYN flooding on port 3306

Hi folks,

I have here a database node running

# rpm -qa | grep mysql-server mysql55-mysql-server-5.5.52-1.el6.x86_64

on

# virt-what vmware

that seems to have a connection problem:

# dmesg |grep SYN |tail -5 possible SYN flooding on port 3306. Sending cookies. possible SYN flooding on port 3306. Sending cookies. possible SYN flooding on port 3306. Sending cookies. possible SYN flooding on port 3306. Sending cookies. possible SYN flooding on port 3306. Sending cookies.

I adapted already following:

# sysctl -a |grep -E 'maxconn|syn_backlog' net.core.somaxconn = 2048 net.ipv4.tcp_max_syn_backlog = 2048

but ListenOverflows and ListenDrops values are still high

# cat /proc/net/netstat | awk '{print $21 "-" $22 }' ListenOverflows-ListenDrops 13568-13568

any suggestion?

-- Thanks, LF