Hello! I reviewed some of the links and I couldn't get this working.
iptables -L reveals
[[email protected] /]# iptables -L
/lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o: init_module: Device or resource busy
Hint: insmod errors can be caused by incorrect module parameters, including invalid IO or IRQ parameters
/lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o: insmod /lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o failed
/lib/modules/2.4.2-2/kernel/net/ipv4/netfilter/ip_tables.o: insmod ip_tables failed
iptables v1.2.4: can't initialize iptables table `filter': iptables who? (do you need to insmod?)
Perhaps iptables or your kernel needs to be upgraded.
Edit: I just looked up it's PTR record, and it points to dhcp065-024-022-001.columbus.rr.com. DHCP stands for Dynamic Host Control Protocol. Basically, it's a protocol for dynamically assigning IP addresses on a network. Unless RR has some non-standard methods for assigning their addresses, he has a dynamic address and it WILL change. Blocking his current address probably won't do much good. Not to mention that he can just use another computer remotely, and unfortunately it's probably not going to help.
Why are you blocking him though? There's a good chance there are other, more effective solutions to the problem. Maybe I'll even know one
Another edit : Just in case anyone here is confused about it, having dhcp in a FQDN doesn't necessarily mean the host it points to uses DHCP, nor does using DHCP add dhcp to a host's name! In this case though, it's a good bet RR is putting it there because they do.
It's a good idea to build you own firewall with your own rules - Have a look at some of those scripts and choose what you want to block and what you don't - The variables are infinite.
Temporarily blocking someone is good also - take a look at downloading and installing portsentry - That can be config'd to drop IP's with iptables rules too - as they try to scan you etc they will get blocked - you can flush your iptables whenever suits so that you aren't blocking someone on dhcp etc forever
Persistent ones that are scannning your ports or just people that you don't want looking at your machine at all can be added to your /etc/hosts.deny or your firewalls blacklist (depending upon which firewall script, if any you decide to use.)