If you want to block ip of network traffic, you can achieve through iptables under Linux, instructions are as follows:
Just want to block the ip method above IP_ADDRESS position before it.
There is a case that you do not want all traffic on an ip blockade, just blockade designated port port number, you can do this:
More instructions through the iptables -destination-port option, the command block only port 25 traffic.
But if simply enter iptables blocking IP, when the host reboot or restart iptables, the added rule will delete all under Redhat / Centos can use the following command to rule stored within config file:
If you want to remove the blockade, so long as the above command iptables -A -D can be changed, for example:
service iptables save