Here's a script I'm using to create some tables which will only allow in on ports I'm running services. One of the problems I'm havng is that I can't ping the Internet with a DNS address from this machine. I've allowed everything in the OUTPUT table and can ping the Internet when using a straight IP, but when I type in "ping google.com" the machine hangs for a few seconds and gives me a server request error. I know it's something with my rules because when I flush them all I can ping google.com just fine. Any ideas would be greatly appreciated. I'm guessing it's something trivial but can't put my finger on it yet.

thanks

#!/bin/bash
########## Beginning ###########################################################

# Define Interfaces/Networks

# Inside/Intranet Interface
INSIDEIP="192.168.7.55"
INSIDEINT="eth0"

# External/Internet Interface # OUTSIDEIP=
# OUTSIDEINT=

# LAN Network
LAN="192.168.7.0/24"

# Admin Host
ADMIN="192.168.7.51"

# Define other Variables

RULE="/usr/sbin/iptables"

# Flushing All rules/chains
$RULE -A INPUT LOG
$RULE -A OUTPUT LOG
$RULE -A FORWARD LOG
$RULE -P INPUT DROP
$RULE -P OUTPUT DROP
$RULE -P FORWARD DROP
$RULE -F INPUT
$RULE -F OUTPUT
$RULE -F FORWARD

# Adding Permittable Network/Hosts/Ports to Input Table on Internal Interface

# Allowing DNS,FTP,SSH,Webmin,HTTP,SWAT,and Samba to Server

$RULE -A INPUT -i $INSIDEINT --proto icmp --icmp-type any -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 21 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp -s $ADMIN --dport 22 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 53 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 80 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 137 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 138 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 139 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp --dport 445 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp -s $ADMIN --dport 901 -d $INSIDEIP -j ACCEPT
$RULE -A INPUT -i $INSIDEINT --proto tcp -s $ADMIN --dport 10000 -d $INSIDEIP -j ACCEPT

# Denying Everything on Local Network

# Adding entry to allow everything originating from Internal Interface out
$RULE -A OUTPUT -j ACCEPT

########## END ################################################################

Hello,

Please add the following in rule in your existing script.

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

yep that did it, thanks a lot

If your still having problems you may want to allow
UDP 53.

iptables -A INPUT -p udp --sport 53 -j ACCEPT

would do the trick. This should allow DNS traffic
over UDP protocol. I read somewhere that udp 53
is more for queries, and tcp 53 is more for zone transfers,
but I may be mistaken