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Kill tcp connection with tcpkill on CentOS

Install tcpkill
yum -y install dsniff --enablerepo=epel

View connections
netstat -tnpa | grep ESTABLISHED.*sshd.

Block with ip tables
iptables -A INPUT -s IP-ADDRESS -j DROP

Kill connection
tcpkill -i eth0 -9 port 50185

Block brute forcing - iptables rules

iptables -L -n

iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent --set
iptables -I INPUT -p tcp --dport 22 -i eth0 -m state --state NEW -m recent  --update --seconds 600 --hitcount 3 -j DROP

iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set --name ssh --rsource
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent ! --rcheck --seconds 600 --hitcount 3 --name ssh --rsource -j ACCEPT

service iptables save
service iptables restart
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