why my firewall script work only for some sites?
I have a firewall script
It provides NAT and allow clients to visit only 3 sites plus DNS servers
On client machine the 1st site (www.debian.org) can be viewed.
but other two sites have problems
the browser display only title bar
in other words it is displayed partially
Note the other two sites are in Chinese
After I uncomment two commands(which reduce security),
the two sites can be viewed.
It seems to me that the problem is specific to etch (kernel 2.6)
The script works fine for the two sites in sarge (kernel 2.4)
below is my firewall script:
#!/bin/sh
#
# rc.firewall-iptables
FWVER=0.76
echo -e "\n\nLoading simple rc.firewall-iptables version $FWVER..\n"
IPTABLES=/sbin/iptables
DEPMOD=/sbin/depmod
MODPROBE=/sbin/modprobe
DNS1="219.233.241.166"
DNS2="211.167.97.67"
SITE1="www.debian.org"
SITE2="trade.gtja.com"
SITE50="ebank.spdb.com.cn"
EXTIF="eth1"
INTIF="eth0"
echo " External Interface: $EXTIF"
echo " Internal Interface: $INTIF"
echo -en " loading modules: "
echo " - Verifying that all kernel modules are ok"
$DEPMOD -a
echo "----------------------------------------------------------------------"
echo -en "ip_tables, "
$MODPROBE ip_tables
echo -en "ip_conntrack, "
$MODPROBE ip_conntrack
echo -en "iptable_nat, "
$MODPROBE iptable_nat
echo "----------------------------------------------------------------------"
echo -e " Done loading modules.\n"
echo " Enabling forwarding.."
echo "1" > /proc/sys/net/ipv4/ip_forward
echo " Clearing any existing rules and setting default policy.."
$IPTABLES -P INPUT DROP
$IPTABLES -F INPUT
$IPTABLES -P OUTPUT DROP
$IPTABLES -F OUTPUT
$IPTABLES -P FORWARD DROP
$IPTABLES -F FORWARD
$IPTABLES -t nat -F
#$IPTABLES -A INPUT -j ACCEPT
#$IPTABLES -A OUTPUT -j ACCEPT
$IPTABLES -A FORWARD -s $DNS1 -j ACCEPT
$IPTABLES -A FORWARD -d $DNS1 -j ACCEPT
$IPTABLES -A FORWARD -s $DNS2 -j ACCEPT
$IPTABLES -A FORWARD -d $DNS2 -j ACCEPT
$IPTABLES -A INPUT -s $DNS1 -j ACCEPT
$IPTABLES -A INPUT -s $DNS2 -j ACCEPT
$IPTABLES -A OUTPUT -d $DNS1 -j ACCEPT
$IPTABLES -A OUTPUT -d $DNS2 -j ACCEPT
$IPTABLES -A FORWARD -s $SITE1 -j ACCEPT
$IPTABLES -A FORWARD -d $SITE1 -j ACCEPT
$IPTABLES -A FORWARD -s $SITE2 -j ACCEPT
$IPTABLES -A FORWARD -d $SITE2 -j ACCEPT
$IPTABLES -A FORWARD -s $SITE50 -j ACCEPT
$IPTABLES -A FORWARD -d $SITE50 -j ACCEPT
echo " Enabling SNAT (MASQUERADE) functionality on $EXTIF"
$IPTABLES -t nat -A POSTROUTING -o $EXTIF -j MASQUERADE
echo -e "\nrc.firewall-iptables v$FWVER done.\n"
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