[CentOS] iptables to block region-specific ip's?

Wed May 11 23:50:46 UTC 2011
David Milholen <dmilholen at wletc.com>

On 5/11/2011 2:08 PM, Robert Spangler wrote:
> On Wednesday 11 May 2011 12:58, the following was written:
>>   I'm running fail2ban on my centos machine. It's handling sshd and
>>   postfix, and is working quite well. From the reports I'm seeing all
>>   the atempts are from a certain registrar's region, I won't name it,
>>   and was wondering instead of blocking individual ip's if there was a
>>   way I could block with iptables the complete region of ip's. I realize
>>   this will cut off a good majority of the world, but this is something
>>   i'm still curious about?
> iptables -I INPUT -i eth0 -s x.x.x.x/24 -j DROP
> Replace the x's with the start of the ip address range you want to block and
> also make sure you are using the correct bit mask for that range.  If the
> interface is something other then eth0 then you will need to replace that too
> with the correct interface.  The '-I' will place this rule as the very first
> rule in the chain.  If you are using a passthrough box then replace INPUT
> with FORWARD.
>>   With regards blocking ip's and fail2ban, which method is better in
>>   terms of system resources, blocking via iptables as in the case of
>>   sshd or blocking via hosts.deny as in the case of postfix?
> I don't know the answer to this.  I prefer IPTABLES.
More efficient using iptables to stop it before its processed in the 
case of mail.
Also, look at "Spamdyke" as an alternative to stop senders,RDNS or ip 


David Milholen
Project Engineer
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