[gentoo-user] Help with script for iptables

[Mick]

Hi All,

I have been using Daniel Robbins' basic script for years but now on a laptop I 
have more than one ways of connecting to the Internet.  The script uses the 
variable UPLINK to define the incoming interface like so:
==============================================
#change this to the name of the interface that provides your "uplink"
#(connection to the Internet)

UPLINK="eth0"

if [ "$1" = "start" ]
then
        echo "Starting firewall..."
        iptables -P INPUT DROP
        iptables -A INPUT -i ! ${UPLINK} -j ACCEPT
        iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
[snip...]
==============================================

I would like to define more than one iface in UPLINK, e.g. eth0, wlan0, ppp0.  
How am I supposed to do this?  I've tried space, comma and colon as 
delimiters, but all fail.  I've also tried entering UPLINK="iface_name" one 
on each line, but the last line seems to be the one that is always used.

I'd very much appreciate your script savvy guidance here, because I couldn't 
fight my way out of a paper bag when it comes to scripting . . .  :)
-- 
Regards,
Mick