high cpu usage on natd / dhcpd

[Eggert, Lars]

Hi,

On Feb 7, 2013, at 13:40, Ian Smith <smithi at nimnet.asn.au> wrote:
> On Thu, 7 Feb 2013 08:08:59 +0000, Eggert, Lars wrote:
>> On Jan 31, 2013, at 16:03, Matthew Luckie <mjl at luckie.org.nz> wrote:
>>> 
>>> 00510 allow ip from me to not me out via em1
>>> 00550 divert 8668 ip from any to any via em1
>>> 
>>> Rule 510 fixes it.
>> 
>> Yep, it does. Can I ask someone to commit this to rc.firewall?
> 
> The ruleset Matthew posted bears no resemblance to rc.firewall, so I 
> don't see that (or how) it solves any generic problem.

sorry for having been imprecise. What I was asking for was this change:

--- /usr/src/etc/rc.firewall	2012-11-17 12:36:10.000000000 +0100
+++ rc.firewall	2013-02-06 11:35:45.000000000 +0100
@@ -155,6 +155,7 @@
 	case ${natd_enable} in
 	[Yy][Ee][Ss])
 		if [ -n "${natd_interface}" ]; then
+			${fwcmd} add 49 allow ip from me to not me out via ${natd_interface}
 			${fwcmd} add 50 divert natd ip4 from any to any via ${natd_interface}
 		fi
 		;;

>> (And I wonder if the rules for the ipfw kernel firewall need a 
>> similar addition, because the system locks up under heavy network 
>> load if I use that instead of natd.)
> 
> Which rc.firewall ruleset are you referring to?

My rc.conf has:

	gateway_enable="YES" 
	firewall_enable="YES" 
	firewall_type="OPEN" 
	natd_enable="YES"
	natd_interface="bce0"

With the patch above, that seems to work fine.

I tried to replace the natd_* lines with:

	firewall_nat_enable="YES"
	firewall_nat_interface="bce0"

which caused the machine to lock up under load, similar to when natd started eating CPU cycles. This made me wonder if a similar patch to the above for the firewall_nat_* case in rc.firewall might be needed.

>  There certainly are 
> problems with the 'simple' ruleset relating to use of $natd_enable vs 
> $firewall_nat_enable (not to mention the denial of ALL icmp traffic) 
> that I posted patches to a couple of years ago in ipfw@ to rc.firewall 
> and /etc/rc.d/{ipfw,natd) addressing about 4 PRs .. sadly to no avail.
> 
> I suggest following up to ipfw@ (cc'd) rather than net@

Will subscribe, thanks.

Lars