Hi
My system is running kernel 2.4.20 with iptables compiled into the
kernel. The system has 2 interfaces. ETH0 is connected to the Internet
(via cablemodem) and ETH1 is connected to my home LAN which has only one
W2K laptop.
My W2K is configured with the Linux system as the gateway. Both systems
can ping each other.
However my laptop is not able to go out to the Internet.
I am desperately trying to make my W2K laptop connect to the Internet.
Please let me know how to make this work.
Thank you in advance.
Subba Rao
subba3@cablespeed.com
#!/bin/sh
echo "Starting Firewall....."
INTERNAL_NET="10.0.0.0/24"
INTERNET=`ifconfig eth0 | grep inet | cut -d : -f 2 | cut -d \ -f 1`
# Flush the tables
/usr/sbin/iptables -F INPUT
/usr/sbin/iptables -F OUTPUT
/usr/sbin/iptables -F FORWARD
/usr/sbin/iptables -t nat -F
# Set default policies for packet entering this box
iptables -P INPUT DROP
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
# Allow some packets in but accept all those on the internal interface
/usr/sbin/iptables -A INPUT -i lo -j ACCEPT
/usr/sbin/iptables -A INPUT -i eth0 -j ACCEPT
/usr/sbin/iptables -A INPUT -i eth1 -j ACCEPT
# Masquerade internal system with the public IP address
iptables -t nat -A POSTROUTING -d $INTERNAL_NET -o $INTERNET -j ACCEPT
iptables -t nat -A POSTROUTING -o $INTERNET -s $INTERNAL_NET -j MASQUERADE
# Block inbound connections
/usr/sbin/iptables -A INPUT -i eth0 -p tcp --syn -j DROP
echo 1 > /proc/sys/net/ipv4/ip_forward
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
