Firewall configuration

UFW configuration to redirect and masquerade from vpn to internal address
Taken from a Raspberry Pi which works

# Generated by iptables-save v1.4.14 on Mon Mar 27 00:04:08 2017
*filter
:INPUT ACCEPT [3796:458494]
:FORWARD ACCEPT [891:104728]
:OUTPUT ACCEPT [3014:356934]
-A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT
COMMIT
# Completed on Mon Mar 27 00:04:08 2017
# Generated by iptables-save v1.4.14 on Mon Mar 27 00:04:08 2017
*nat
:PREROUTING ACCEPT [301:36128]
:INPUT ACCEPT [46:5786]
:OUTPUT ACCEPT [157:11272]
:POSTROUTING ACCEPT [19:1254]
-A POSTROUTING -o tun0 -j MASQUERADE
COMMIT
# Completed on Mon Mar 27 00:04:08 2017