cant ping from behind proxy box

[Zoltan Szecsei]

Hi,
Sorry - newbie to fedora, and google is driving me mad !

I've just setup up a F17alpha box, and am trying to ping the internet 
from behind my Ubuntu proxy server, which also runs bind.

I have set GATEWAY in /etc/sysconfig/network
I have put nameserver 192.168.0.1 into /etc/resolv.conf
I have done a export http_proxy=http://192.168.0.1:3128

I have done a /etc/init.d/network restart

and I still cannot ping by IP nor by dnsalias name

but this all works from other ubuntu boxes, and of course from the 
server machine itself.
I can also ping all the PCs on my internal network.

Please can someone tell me my deliberate mistake in this regard.

TIA,
Zoltan