Routing all traffic via Raspberry Pi with OpenVPN on a OpenWRT Briged AP

Question

I want to route all traffic on my OpenWRT router via my Raspberry Pi that has a OpenVPN client connection.

I have a simple setup:

+-------------------+            +---------------+
|                   |  Connected |               |
|     ISP MODEM     +------------+OpenWRT Router |
|    192.168.1.1    | to lan port| 192.168.1.2   |
+-------------------+            +--+-----------++
                                    |           |
                                    |           |
                                    |           |
                             +------+-------+   |  +-------------------+
                             | Raspberry Pi |   |  | All other devices |
                             | with OpenVPN |   +--+ connected via WiFi|
                             | 192.168.1.3  |      |    192.168.1.*    |
                             +--------------+      +-------------------+

I literally followed this guide to setup a bridged AP on OpenWRT and this tutorial to setup OpenVPN on my Raspberry Pi. I believe that the settings on the Raspberry Pi are correct.

I tried to change the default gateway as following on my OpenWRT router:

root@OpenWrt:~# ip route del default
root@OpenWrt:~# ip route add default via 192.168.1.3
root@OpenWrt:~# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
default         192.168.1.3     0.0.0.0         UG    0      0        0 br-lan
192.168.1.0     *               255.255.255.0   U     0      0        0 br-lan

On my router I see that this worked because it now has an IP of the VPN provider

root@OpenWrt:~# wget -qO- http://canihazip.com/s
46.166.186.213

However on all my devices that are connected to the OpenWRT router's WiFi or cable, I still get my old ISP's IP.

I realize that there are many similar questions here, however non off the solutions worked for me. I know little about networks and start to think that what I want is not possible with a bridged AP.

Answer 1

It is not possible to do this with a bridged access point set-up.

And to do this you don't need the Raspberry Pi at all.

Make the following setup:

+-------------------+            +---------------+
|                   |  Connected |               |
|     ISP MODEM     +------------+OpenWRT Router |
|    192.168.1.1    | to wan port| 192.168.2.1   |
+-------------------+            +-------+-------+
                                         |
                                         |
                                         |
                              +----------+--------+
                              | All other devices |
                              | connected via WiFi|
                              |    192.168.2.*    |
                              +-------------------+

On a router with default settings:

1. Open /etc/config/network and find config interface 'lan'.
2. There you change option ipaddr '192.168.1.1' to option ipaddr '192.168.2.1'.
3. Then follow a guide to set-up OpenVPN on the OpenWRT router. I used this guide on GitHub which is for the Private Internet Access provider, but it should apply to all providers that support OpenVPN. Note that in the tutorial I link, they use 192.168.1.1, instead you should now use 192.168.2.1.