Can't get IP forwarding to work

[ktb <x.y.f@home.com>]

I'm following the networking FAQ and can't get forwarding to work.  I'm
trying to get Open BSD set up as a firewall forwarding to my linux box.
 I can ping back and forth between the boxes.  I can ping out to the
net from my firewall.  I've used the command 
"sysctl -w net.inet.ip.forwarding=1"  

"route show" says --
destination		gateway				flags
default		 	<my isp gateway IP>		UG
<isp network IP>		link#1				U

Internal card ne4 
ip 192.168.10.1 
netmask 255.255.255.0 
broadcast 192.168.10.255

External card ne3 
ip <my ip assigned by my isp> 
netmask 225.255.255.0 
broadcast  <isp's broadcast ip number>

My linux box is set up with the gatway pointing to 192.168.10.1.   What
else am I missing?  I'm using a fresh install of 2.7. 
Thanks,
kent