HOWTO+-+Linux+Masquerade

How To Masquerade On Linux (Internet Connection Sharing)
It's very simple to masquerade (internet connection sharing in Windows language ) on Linux with a few lines of iptables and ip_forward commands. First of all you have to flush and delete existing firewall rules. So flush rules by typing in terminal: iptables -F iptables -t nat -F iptables -t mangle -F Now delete these chains: iptables -X iptables -t nat -X iptables -t mangle -X Now it's time to save the iptables rules so type: service iptables save service iptables restart Now all rules and chains have been cleared! Check it in /etc/sysconfig/iptables which has all default rules set to accept. Now open /etc/rc.d/rc.local and insert the line: code echo "1" > /proc/sys/net/ipv4/ip_forward code And then save and close the file. Now asuming that your internet interface is eth0, type: iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE service iptables save service iptables restart Note: check if iptables is set to start during boot up. Or check the status of your iptables service: chkconfig –list iptables If level 5 is on then it's ok othewise start the service at level 5 or level 2345.