Unable to install CSF Firewall

I have VPS server on Godaddy with Cent OS 5.9 virtuozzo and are 50 websites hosted there. Currently I faced lots of BrutForce attacks from different countries. Also they, hackers, entered into WHM and changed different settings even though I am continually changing my password.
To protect from these attacks I have tried so many times to install CSF firewall but I am facing following issue with installation.
After CSF installation when I am running csftest.pl script, it give me these errors..

Code:

Testing ip_tables/iptable_filter...OK
Testing ipt_LOG...OK
Testing ipt_multiport/xt_multiport...OK
Testing ipt_REJECT...OK
Testing ipt_state/xt_state...FAILED [FATAL Error: iptables: No chain/target/match by that name.] - Required for csf to function
Testing ipt_limit/xt_limit...OK
Testing ipt_recent...OK
Testing xt_connlimit...FAILED [Error: iptables: No chain/target/match by that name.] - Required for CONNLIMIT feature
Testing ipt_owner/xt_owner...OK
Testing iptable_nat/ipt_REDIRECT...FAILED [Error: FATAL: Module ip_tables not found.] - Required for MESSENGER feature
Testing iptable_nat/ipt_DNAT...FAILED [Error: FATAL: Module ip_tables not found.] - Required for csf.redirect feature

RESULT: csf will not function on this server due to FATAL errors from missing modules [1]

I thought that some modules of iptables are missing. So I tried this command to activate all modules

Code:

modprobe iptables_module

but for all modules it showing

Code:

FATAL: Module iptables_module not found.

Then I noticed that, in containers I can activate modules by editing /etc/sysconfig/iptables-config this file in this article Enable Firewall in Parallels Virtuozzo Containers
After editing above file, when I restart iptable service, it showing me

Code:

iptables: Loading additional modules: ip_tables ipt_tcp ipt_comment ip_conntrack iptable_filter ipt_LOG is failed.. 

So I can not install firewall in my server because modules of iptables can not activate (may be).
Because of this my server facing lots of attacks. Is there any better solution for this.
* vzctl command not activated in my server.
* I have 50 websites hosted on my server so unable to re-install new linux. Also Godaddy giving same linux version to all VPS with same configuration.

 

So sorry for that.. I have mistakenly typed incorrect version of Cent OS. Its Cent OS 6.9, not 5.9
Is there any available option for 6.9 to install firewall ?