[CentOS] Optimizing CentOS for gigabit firewall

Timo Schoeler timo.schoeler at riscworks.net
Fri Dec 18 20:22:56 UTC 2009

>> 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. ;)


[0] -- http://pcengines.ch/alix.htm

> nate

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