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I am trying to run tunnel all my network traffic on my LAN via an OpenVPN client running inside a docker container.

My router and default gateway is running on 10.10.10.1

I have OpenVPN running on in a docker container with its own IP and all ports open on 10.10.10.25

OpenVPN is connecting to my VPN provider - and if run traceroute from inside the running docker container, the traffic is routing correctly via my VPN - curl also works, routing traffic correctly.

However, if I set my default gateway on any LAN devices to 10.10.10.25, I cannot route to the internet.

Routes in the OpenVPN docker container are:

0.0.0.0/1 via 10.8.8.1 dev tun0
default via 10.10.10.1 dev eth0
10.8.8.0/24 dev tun0  proto kernel  scope link  src 10.8.8.46
10.10.10.0/24 dev eth0  proto kernel  scope link  src 10.10.10.25
128.0.0.0/1 via 10.8.8.1 dev tun0
172.83.40.68 via 10.10.10.1 dev eth0

Ifconfig run in the OpenVPN container gives:

eth0      Link encap:Ethernet  HWaddr 02:42:0A:0A:0A:19
          inet addr:10.10.10.25  Bcast:10.10.10.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2377 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1984 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:370083 (361.4 KiB)  TX bytes:523356 (511.0 KiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:74 errors:0 dropped:0 overruns:0 frame:0
          TX packets:74 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5769 (5.6 KiB)  TX bytes:5769 (5.6 KiB)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:10.8.8.46  P-t-P:10.8.8.46  Mask:255.255.255.0
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:27 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1606 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:2274 (2.2 KiB)  TX bytes:241166 (235.5 KiB)

ipv4 forwarding is enables, and default firewall policies are all ACCEPT

I have also tried NATing on the docker container with the command:

iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE

But I am still unable to get any connection

Some notes:

  • If OpenVPN is not running, I am able to route traffic via the docker container: LAN device -> 10.10.10.25 -> 10.10.10.1 -> WAN
  • OpenVPN is correctly setting up the routes as I am able to access internet from inside the docker container correctly
  • LAN is still accessible via 10.10.10.25 with OpenVPN running

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