How many iptables block rules is too many

Posted by mhost on Server Fault See other posts from Server Fault or by mhost
Published on 2013-10-17T19:00:15Z Indexed on 2013/10/17 21:59 UTC
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iptables

We have a server with a Quad-Core AMD Opteron Processor 2378. It acts as our firewall for several servers. I've been asked to block all IPs from China.

In a separate network, we have some small VPS machines (256MB and 512MB). I've been asked to block china on those VPS's as well.

I've looked online and found lists which requires 4500 block rules. My question is will putting in all 4500 rules be a problem? I know iptables can handle far more rules than that, what I am concerned about is since these are blocks that I don't want to have access to any port, I need to put these rules before any allow. This means all legitimate traffic needs to be compared to all those rules before getting through. Will the traffic be noticeably slower after implementing this? Will those small VPS's be able to handle processing that many rules for every new packet (I'll put an established allow before the blocks)?

My question is not How many rules can iptables support?, its about the effect that these rules will have on load and speed.

Thanks.

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