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Configure internet connection sharing in Ubuntu

Before we continue the following tutorial, you have to make sure that you have configured network interfaces and that you are having a working internet connection. In our example we are going to use eth0 as local area network (ip and eth1 as wide are network.

sudo iptables -A FORWARD -i eth1 -o eth0 -s -m conntrack --ctstate NEW -j ACCEPT

sudo iptables -A FORWARD -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT

Finally we made NAT:

sudo iptables -A POSTROUTING -t nat -j MASQUERADE

Configure the gateway for routing between two interfaces by enabling IP forwarding:

sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"

Edit /etc/sysctl.conf and add these lines or uncomment by removing # or ; in front of them if they are commented:


To be able to have this configuration at every start-up, you should do something like this example. Please note that this is just an example. There are many ways to configure ics to run at boot. I found this easier.

Resources: Ubuntu.com


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