[newbie]DNS on the internet... how to allow connections?

[Marco Nicoloso <marco.nicoloso@fastwebnet.it>]

Hi there,

I solved all of my routing problems which I had before... Now everything 
works fine, but the name resolution. According to the scheme (Trusted 
subnet -> Firewall -> Internet), hosts on my trusted subnet can see the 
DNS properly, they get its address from the DHCP, but they cannot get 
DNS queries satisfacted.

I tried with different rules, but none works:
$IPTABLES -A INPUT -p tcp --dport 53 -j ACCEPT
$IPTABLES -A OUTPUT -p tcp --dport 53 -j ACCEPT
$IPTABLES -A INPUT -p udp --dport 53 -j ACCEPT
$IPTABLES -A OUTPUT -p udp --dport 53 -j ACCEPT

or these:
$IPTABLES -A FORWARD -p tcp -s $DNS1_IP -j ACCEPT
$IPTABLES -A FORWARD -p tcp -s $DNS2_IP -j ACCEPT
$IPTABLES -A FORWARD -p udp -s $DNS1_IP -j ACCEPT
$IPTABLES -A FORWARD -p udp -s $DNS2_IP -j ACCEPT

Do I have to setup my own named, cache queries and requests new ones if 
I need? Or it is just my problem, that I am not able to write rules...?

Thanks in advance

Marco Nicoloso