> Is it ok that ping does not work through the firewall, or there is
> something wrong with my firewall configuration ? The rest, I mean
> netscape, runs fine.

I have three rules like this:

map de0 10.0.0.0/255.255.255.0 -> 209.89.9.68/32 proxy port ftp ftp/tcp
map de0 10.0.0.0/255.255.255.0 -> 209.89.9.68/32 portmap tcp/udp 10000:40000
map de0 10.0.0.0/255.255.255.0 -> 209.89.9.68/32

The first rule makes active ftp work through the NAT and is totally
optional.

The second rule makes sure that tcp and udp packets get NAT'd correctly
(with port mapping because of the many to 1).

The third rule makes everything else work - like ICMP or ping.  If you are
missing the third rule most normal stuff will work but you will not be able
to ping through the NAT.

Good Luck!

Mike.