Pptp doesn't work on router through IPFire


I setup a pptp connection on router, it works fine in this setup:

Internet>CableModem>Router is OK.

But in this setup doesn’t work:
Internet>CableModem>IPFire Firewall>Router doesn’t work.

Is there any step to do in the IPFire Firewall so the pptp connection works?

pptp use a GRE connection wich not use ports so it cannot pass nat without a rule that forward all gre packets to the specific ip of the router. Also keep in mind that only one gre tunnel can used.

Another important thing is that the encryption of pptp is brocken since 2012 (mschap2) so it is insecure and should replaced by a secure vpn like IPSec asap.

Good to know!