[CentOS] Optimizing CentOS for gigabit firewall
pasik at iki.fi
Mon Dec 21 09:07:08 UTC 2009
On Fri, Dec 18, 2009 at 09:36:57PM +0200, sadas sadas wrote:
> I will explain more deeply. I need to deploy a firewall(s) in front of web
> server farm because I need to do billing - I will use CentOS with iptables
> + ipset to store a list if my clients so when client doesn't pay his
> server's IP is out of the list and he can't access the web server.
> Second - I know that iptables is very heavy and it's not recommended to
> use it in gigabit firewall but I don't have a choice as far as I know only
> ipset works with iptables. I don't know can pf store 500 IPs in one list.
> Ipset is written for that purpose.
> I can't find information is there linux or BSD distribution with effective
> firewall that uses optimized algorithm to store hundreds of IPs and to
> forward huge traffic. Any idea?
I've been using Linux (CentOS5) on gigabit firewalls, for thousands of
users. No problems.
Just make sure ip_conntrack_max is big enough, so you don't run out of
There are other things to tune to optimize the performance, but it's
certainly doable with linux+iptables.
> <peter.serwe at gmail.com><centos at centos.org>I'll second damn near everything
> nate said, and hopefully add a tidbit or two.
> If you're new to BSD, you may want to consider the pfsense project in the
> aforementioned active-active configuration.
> It gives you a nice, intuitive gui to manage your failover firewalls, if
> you insist on putting a firewall in front of your web servers.
> Better to secure the box, leave only the ports you need open on the public
> interfaces, and don't firewall them.
> Also, I'd strongly consider running your firewalls with no disk at all. A
> Live CD, CF card or USB Flash to boot off of, remote syslog and
> one less subsystem (disks) to buy/fail makes for some mighty cheap 1U
> servers. A single dual-core with core speeds above 3.0Ghz
> and 4GB of RAM is to pass Gb @ line rate - ethernet overhead. Truth be
> told, it's already being done on much less
> than that. You can also load balance your traffic, albiet somewhat
> primitively with it. If you really want massive throughput, consider
> around with extremely expensive 10G gear, size RAM appropriately, and see
> how PF performs under multi-processor, high-core speed.
> but if you're handling over a Gb of traffic and you can't split the
> application into multiple farms, that's the best move.
> Akamai, for instance, runs 10G to each rack, each rack has around 20-24
> servers, and they run GB to the server.
> pfsense.org has extensive information about hardware requirements,
> features, and what you're looking to do.
> https://calomel.org/network_performance.html is an excellent BSD
> firewall performance site.
> One thing to note, you are claiming to want to deploy this as a passive
> bridge. You cannot do what you want to do
> running anything in bridge mode. The packets need to route somehow. Get
> a /29 from your colo provider and ask
> to have your existing block routed through it once you've tested it.
> Another option for a seamless failover, is to alias a different range of
> IP's to the server interfaces, put a /29 and whatever
> netblock you want to end up being your public IP block on the PFSense
> hardware. When you're convinced everything's
> working through rigorous testing, put a test domain up pointing to that
> block, modify virtualhost entries on the servers to
> respond to that domain with your production web site, and test some more.
> Once you're convinced that's working perfectly,
> make the changes in DNS to point your production domain at the IP's you
> want, and failover will happen with DNS convergence.
> On Fri, Dec 18, 2009 at 9:06 AM, nate <centos at linuxpowered.net> wrote:
> sadas sadas wrote:
> > Hi,
> > I want to configure CentOS on powerful server with gigabit
> > adapters as transparent bridge and deploy it in front of server farm.
> > Can you tell how to optimize the OS for hight packet processing? What
> > configurations I need to do to achieve very hight speeds and thousands
> > packets?
> iptables makes a TERRIBLE firewall, use pf instead
> Also consider how your going to provide redundancy, if you have a web
> server farm you want to protect them with at least two firewalls, not
> I haven't used CARP myself but did setup a pair of pf firewalls about
> 5 years ago in a large network in bridging mode, the layer 3 fault
> tolerance was provided by OSPF on the core switches, the firewalls
> were active-active(with pfsync) since they were layer 2 only.
> Maybe someday linux will fix the overly complex iptables system to
> something that is more manageable, not holding my breath though.
> If you want really high speed(say multi GbE) though you'll want/need
> to go with an appliance based solution.
> Also since your referring to a web server farm, it is perfectly
> acceptable to not use firewalls these days, if you have a good
> load balancer that serves the same role as a firewall in that it
> only passes traffic that you specifically configure it to pass. Also
> in high traffic environments the performance of load balancers
> destroys most firewalls, making investing in a high end firewall
> a very expensive proposition.
> I've worked for the better part of the last 10 years with
> companies who did not have firewalls in front of their web servers
> for this reason, it didn't make sense $ wise, because the benefit
> wasn't there, and the added complexity, and performance implications
> wasn't worth it either. Talk to most load balancing companies and
> they'll tell you this themselves.
> </centos at centos.org></peter.serwe at gmail.com>
> Visible links
> 1. http://pfsense.org/
> 2. https://calomel.org/network_performance.html
> 3. mailto:centos at linuxpowered.net
> 4. http://www.openbsd.org/faq/pf/index.html
> 5. http://www.openbsd.org/faq/pf/carp.html
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