eth1 eth0 and pptpd (vpn)?

Question

VPN

The bottom line is that the Internet is connected to the external network (eth1), the network has static provider addresses configured, everything works as it should. Next, DHCP is configured on eth0.
I wrote iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE in /etc/rc.local, I don’t know how correctly, but the Internet appeared on eth0. Further, in the LAN port of the router, distribution by device + wi-fi.
(the router hangs, I decided to start everything through the server, and leave the router as a switch + wi-fi)
Everything turned out, it worked, I have apache and a lot of things there, it works both on the local ip of the provider and on a personal external one. Everything works except pptp vpn server. At the same time, if you specify the local IP of the provider, everything connects, but the external IP is deaf, Error 619.
Forwarding iptables -A INPUT -p tcp --dport 1723 -j ACCEPT did not help.

Answer 1

In general, I figured it out myself, as always, did
it and it all worked. In fact, this is the name of the ip_nat_pptp module.