Hi,

If you want to block an ip
simply login into ssh

iptables -I INPUT -s xxx.xxxx.xxxx.xxx -j DROP
(please put ip number that you want to block instead of xxx.xxx.xxx.xxx)
/etc/init.d/iptables save

if you want to remove blocked ip ;

iptables -L -n --line-numbers (you will know the #)
and you will see the protocol number, last command is ;

iptables -D INPUT #