I'll bet you are hitting your max connections
check the value of net.ipv4.netfilter.ip_conntrack_max
David Lang
On Thu, 19 Jul 2007, Konstantin Svist wrote:
Date: Thu, 19 Jul 2007 15:17:00 -0700
From: Konstantin Svist <kostya@xxxxxxxxxxx>
To: netfilter@xxxxxxxxxxxxxxxxxxx
Subject: need advice for high traffic network
Hi,
I have a network (LAN) consisting of (mostly) gigabit ethernet on a few
switches. Most of the traffic is taken up by small HTTP reqests. All
computers are running Fedora (all are core 4 through 7).
I've been having some problems with servers not being accessible and just
last night noticed that the problems disappear when I turn off the firewall.
What happens is that there are lots of small HTTP requests and apparently at
some point the firewall starts dropping or disallowing new connections. This
has been verified with both ab (apache benchmark) and plain SSH - a lot of
times the connections time out or take a long time to get established.
There are ~25 rules total (as listed by 'iptables -L')
As a temporary measure, I've turned off firewalls on more of the servers
until I can figure out a better solution - I'd like to have a firewall on
each server, but performance is more important.
I'l looking at nf-HiPAC right now - will probably try it some time soon.
Beyond that, I'm out of ideas for the moment.
Is there anything else I can do?
Any other firewalls? Tricks with rearranging the rules?
etc...
Thanks!
Notes:
* Problems do not seem to be limited to any specific Fedora version or
hardware.
* external firewalls are out of the question, unless they're really small &
cheap: there are >40 servers in the internal network and the number is
growing
