Linux Shell Scripting Cookbook - Third Edition

How to do it...

1. Connect to the Internet. In this recipe, we are assuming that the primary wired network connection, eth0, is connected to the Internet. Change it according to your setup.
2. Using your distro's network management tool, create a new ad hoc wireless connection with the following settings:
   • IP address: 10.99.66.55

• Subnet mask: 255.255.0.0 (16)

3. Use the following shell script to share the Internet connection:

        #!/bin/bash 
        #filename: netsharing.sh

        echo 1 > /proc/sys/net/ipv4/ip_forward 

        iptables -A FORWARD -i $1 -o $2 \
            -s 10.99.0.0/16 -m conntrack --ctstate NEW -j ACCEPT 

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

        iptables -A POSTROUTING -t nat -j MASQUERADE

4.  Run the script:

 ./netsharing.sh ...