TCPKILL command on Linux is useful to kill connections made by malicious IP’s to the server, TCPKILL can be installed on the server (CentOS) using the below command

Installation in CentOS:

yum -y install dsniff --enablerepo=epel

TCPKILL Syntax:

1. Kill all connection on port 25

tcpkill -i eth0 port 25

2. Kill all connections IN/OUT from an IP

tcpkill host 10.10.10.23