Learnings.: Enable IP Forwarding in Linux

echo 1 > /proc/sys/net/ipv4/ip_forward
 #This is temporary

 #for permanent >>

 
#vim /etc/sysctl.conf

net.ipv4.ip_forward = 1

 <save it>

#sysctl -p or

#service network restart

Configure iptables :

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# /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

--optional---next-->

# /sbin/iptables -A FORWARD -i eth0 -o eth1 -m state   --state RELATED,ESTABLISHED -j ACCEPT 

# /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT

Learnings.