a few things
You could do a few things.
First - place those ip's into iptables as a deny...
PHP:
iptables -I INPUT -s 1.1.1.1 -j DROP
* (where 1.1.1.1 would be the ip address you want to block)
If you are being attacked or abused by a particular host, just enter the following command to deny all access to the host:
/sbin/route add -host <ip address> reject
Replace with the IP address of the host you want to block. The address will stay blocked until you bounce the interface. Alternatively, you could allow access by:
PHP:
/sbin/route del -host <ip address> reject
For a more permanent rejection, of course, use your firewall - or install one.
Chirpy has an excellent one on here - do a search for lfd and take the sticky found there.
Its free - but you need to know what your doing prior to installing it.
Get stuck - send a PM to me