iptables rules for vpn config

rc.local

# for ISAKMP (handling of security associations)
iptables -A INPUT -p udp --dport 500 --j ACCEPT
# for NAT-T (handling of IPsec between natted devices)
iptables -A INPUT -p udp --dport 4500 --j ACCEPT
# for ESP payload (the encrypted data packets)
iptables -A INPUT -p esp -j ACCEPT
# for the routing of packets on the server
iptables -t nat -A POSTROUTING -j SNAT --to-source %IP% -o eth0
# internet access
iptables -t nat -A POSTROUTING -s 10.0.42.0/24 -o eth0 -m policy --dir out --pol ipsec -j ACCEPT
iptables -t nat -A POSTROUTING -s 10.0.42.0/24 -o eth0 -j MASQUERADE