nat & firewall thru iptables

[jkmartha]

fedora core -2.

i have 2 NIC on my system. suppose,
eth0 is 60.61.62.63 (public IP ) and
eth1 is 192.168.239.20 (for internal users).
i want to configure nat as well as firewall. following are the commands which i am planning to run. will it be ok ??

FLUSH

iptables -t filter -F INPUT
iptables -t filter -F OUTPUT
iptables -t filter -F FORWARD
iptables -t nat -F PREROUTING
iptables -t nat -F POSTROUTING
iptables -t nat -F OUTPUT

DEFAULT policies
iptables -t filter -P INPUT DROP
iptables -t filter -P OUTPUT ACCEPT
iptables -t filter -P FORWARD DROP
iptables -t nat -P PREROUTING ACCEPT
iptables -t nat -P POSTROUTING ACCEPT
iptables -t nat -P OUTPUT ACCEPT

Set up the firewall rules
iptables -t filter -A INPUT -i ${LOOPBACK} -j ACCEPT
iptables -t filter -A INPUT -i eth1 -j ACCEPT
iptables -t filter -A INPUT -i eth0 state --state RELATED,ESTABLISHED -j ACCEPT
iptables -t filter -A FORWARD -i eth1 -o eth0 -j ACCEPT
iptables -t filter -A FORWARD -i eth0 -o eth1 state --state RELATED,ESTABLISHED -j ACCEPT

Set up ip masquerading
iptables -t nat -A POSTROUTING -s 192.168.239.0/255.255.255.0 -o eth0 -j MASQUERADE


i can understand this is a lengthy post . but i have been trying this since 2 days. Is this OK ?? pliz help....

[parisse]

www.tldp.org
guides...
securing and optimizing linux
Nat section..