[Cialug] Ip forward question

[albus]

I've got a new proxy arp firewall setup with CentOS 5.4

It has only 2 nics.

I've run 
echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp
echo 1 > /proc/sys/net/ipv4/conf/eth1/proxy_arp

And it all works. However every time I service network restart or reboot it drops forwarding
until I re-issue the 2 echo lines.

Something is over writing it. From what I've Googled it's a problem others have had as well. But
I haven't run in to how to make it permanant.

I'm about to just include the 2 echo lines in /etc/rc.local 
But I'd rather know where to make it stick instead.

Any ideas?