connect to internet from openvpn tunnel

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http://serverfault.com – I have a windows7 that uses openvpn.I want to connect my win7 to internet through openvpn tunnel.my openvpn server is on ubuntu and i can connect to internet from ubuntu's eth0 with bridging it to host NIC.I googled but no success is achieved. when win7 connected to vpn, an ip address such is assigned to it. i want to do this work such that i can test traffic shaping settings for win7 client. i try with push redirect gateway and some iptables rules but as i mentioned before i did not succeed. please guide me. (HowTos)