The VPN server running is windows 2012 server default VPN, which uses GRE protocol. I am able to have VPN connection to that remote vpn server, from my intranet single IP only. But I am not able to connect for range of intranet IP 172.16.14.0/24. The problem is with linux router, which is doing NAT. My iptable for nat table looks like this for working vpn connection (for single IP), allowing gre protocol:
iptables -I PREROUTING -t nat -p 47 --src 202.xx.yy.abc -j DNAT --to-destination 172.16.14.15 iptables -I POSTROUTING -p 47 -t nat --src 172.16.14.15 -j SNAT --to-source 202.xx.yy.zz iptables -t nat -A POSTROUTING -o eth2 -j MASQUERADE iptables -A INPUT -p 47 -j ACCEPT
This rule works fine for single IP 172.16.14.15. How can I make this works for whole 172.16.14.0/24 range so that I can have VPN connection to the remote VPN server ?