How to configure UFW to allow IP Forwarding?

Question

I have UFW, OpenVPN and Virtualbox installed on my home server. I have a host-only network for my virtual machine guests (vboxnet0) set up with the IP range 10.0.1.0, and another IP range of 10.0.0.0 configured on the other end of the OpenVPN connection.

IP Forwarding is configured on the host, so when UFW is disabled they can talk to each other without any issues. However, I'd like to run UFW as this host will be web-accessible and I'd like some access control.

How can I configure UFW to allow this sort of traffic?

I've tried various combinations of: ufw allow allow in|out on vboxnet0|tun0 with no success.

My UFW rules are:

root@gimli:~# ufw status
Status: active

To                         Action      From
--                         ------      ----
22                         ALLOW       Anywhere
Anywhere                   ALLOW       10.0.0.0/16
Anywhere on vboxnet0       ALLOW       Anywhere
Anywhere on tun0           ALLOW       Anywhere

Anywhere                   ALLOW OUT   Anywhere on vboxnet0
Anywhere                   ALLOW OUT   Anywhere on tun0

Any help would be greatly appreciated.

Answer 1

I figured it out.

Edit /etc/default/ufw and set DEFAULT_FORWARD_POLICY to ACCEPT:

DEFAULT_FORWARD_POLICY="ACCEPT"