vpnc and tun0 and iptables

I recently installed vpnc on a laptop running Debian Sid. After fiddling
around I realized I need to change my custome iptables script to make
vpnc work. I allowed access to the tun0 interface and was able to work
by connecting to my university.

Since then I have modified my firewall script. Now, I basically
implement all interfaced rules to all interfaces (eth0, wlan0 and tun0).
So I do:

default stuff here (clearing chains, creating new ones, default policy ,
etc)
for NIF in "eth0 wlan0 tun0"; do
block ping
block invalid address
allow ssh to NIF
allow stuff for realplayer at NIF
allow dhcp stuff at NIF
etc.
done

Is this the correct way to do it? I am basically considering tun0 just
at eth0 or wlan0 on which I want to allow SSH and other stuff.

Forgive me if the above it not accurate. If you wish, I can post my
iptables rules here.

regards,
->HS


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