Too many dynamic rules

Dan Nelson dnelson at
Tue Nov 13 02:27:10 UTC 2012

In the last episode (Nov 12), Darrel said:
> Hello,
> Today I booted r242670 from the console and noticed an error.  This
> is one line from the end of dmesg:
> ipfw: ipfw_install_state: Too many dynamic rules
> The ruleset has always been dynamic and has no additional rules.
> Search engines produced similar error messages, but no information
> that seems to be the correct solution.
> I have a basically identical ruleset on fbsd91 and no error message.

That means that the dynamic rules generated by the keep-state keyword hit
the currently-confgured limit.  If you get hit with a lot of random traffic
that matches a keep-state rule, you'll get that message.  It's not the rules
themselves that cause this, it's the traffic.

Run "sysctl net.inet.ip.fw.dyn_max net.inet.ip.fw.dyn_count" and compare the
two values.  If count is near to dyn_max, you can simply raise dyn_max. 
It's a writeable sysctl.  I set it to 65535 on my systems in
/etc/sysctl.conf with no apparent ill effects.
	Dan Nelson
	dnelson at

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