[CentOS] Optimizing CentOS for gigabit firewall

Timo Schoeler timo.schoeler at riscworks.net
Fri Dec 18 20:55:14 UTC 2009

> What about NetBSD? I heard that NetBSD has the best network stack out
> there. Maybe NetBSD with pf is the best choice?

NetBSD is a very nice OS, I personally like it most (out of all BSDs out
there); however, as can be read on


there's the 'usual lag': OpenBSD implements feature X in 4.6, wait some
time to see it implemented elsewhere.

One of the biggest strengths of OpenBSD is that it's really a completely
rounded piece of work. Keep it that way. pf will perform best on
OpenBSD, with all the nice features it has.



>>>> 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?
>>> Hundreds?
>>> http://www.openbsd.org/faq/pf/tables.html
>>> "A table is used to hold a group of IPv4 and/or IPv6 addresses.
>>> Lookups against a table are very fast and consume less memory and
>>> processor time than lists. For this reason, a table is ideal for
>>> holding a large group of addresses as the lookup time on a table
>>> holding 50,000 addresses is only slightly more than for one
>>> holding 50 addresses. Tables can be used in the following ways:
>>> * source and/or destination address in filter, NAT, and
>>> redirection rules. * translation address in NAT rules. *
>>> redirection address in redirection rules. * destination address
>>> in route-to, reply-to, and dup-to filter rule options."
>>> nuff said ?
>>> I love linux, I've been using it for almost 15 years now, I
>>> absolutely hate iptables(and ipchains, and ipfwadm). By contrast
>>> I absolutely hate everything about OpenBSD except for pf(which I
>>> love, ipfw and ipf aren't too bad either, at least for the era),
>>> so I use OpenBSD for firewalls, and linux for everything else.
>> I can back this; during 2009, I deployed a bunch of load balancers 
>> running OpenBSD (using pf, carpd, and relayd). I used to be a super
>> die hard BSD guy, but through the years and having
>> used/deployed/propagated NetBSD, then FreeBSD, then OpenBSD, then
>> NetBSD again, I took one of my usual once-a-year looks at GNU/Linux
>> (this time, it was CentOS, after having worked with RHEL for some
>> years), I got settled here.
>> Long story short: I'd really recommend OpenBSD for your task.
>> iptables really sucks. I recently deployed some machines running
>> several virtual instances (however still the cheapest *proven* way
>> to get several IP stacks in Linux) doing L2 routing, I threw
>> iptables off of that machines because it just can't handle stuff at
>> that rate. OpenBSD rocks, I even have a setup running
>> (active-active, load balanced) at about 40Mbps using Alix boards
>> [0] -- they rock, and they are no way busy.
>> OpenBSDs documentation is the best out there, it's documentational 
>> quality is what I really really badly miss in the Linux world.
>> However, the community is a bunch of (sorry in advance) assholes.
>> But this is well known throughout the internet, so: You have been
>> warned. Great product, totally lame vendor. ;)
>> Timo
>> [0] -- http://pcengines.ch/alix.htm
>>> nate

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