Openvpn - enabled redirect gateway but can't access any websites

do few things

1 ensure you have pkt forwarding enabled on vpn server:

cat /proc/sys/net/ipv4/ip_forward 

it should be 1, if it's not run:

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

2 for a good measure add [ not really needed since you allow traffic from/to tun0.. ]

iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

3 and finally - nat the traffic coming from vpn - that is: replace the source ip address of your connection with address of the server

iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

i think the last point is the missing one...