Use 2 network adapters on Windows 10 at once

[RileyTheFox]

Hey. So I have setup OpenVPN on my server to use for a specific application (to allow people to play games with me without giving away my real IP) but the only problem is, is that all traffic on my PC is routed through the VPN. This VPN has a lot lower internet speed than my ISP internet speed, so I want to know whether or not I can tell Windows to send traffic through my regular Ethernet network and the VPN network at the same time.

 

In Control Panel, I have 2 adapters:

(OpenVPN is disabled right now)

 

The way I want it to work is that the OpenVPN connection is set as "Public" and my Ethernet adapter is set as "Private". In my firewall I've set everything to private other than the application that will be ran through the VPN (which is on the public network).

 

How can I tell Windows to use both private and public at the same time, and only the application on public will use the VPN? Thanks.

[Jarno.]

 

The only way I can come up with is by modifying your routing table. But this would be tricky as you need to know exactly what the source IP or subnet's are. See example below of my system. They network 10.0.3.0/24 is a virtual network for example which is bridged to wireless interface wlp3s0. In your situation this would go to your secondary NIC and it won't be bridged. Easiest way might be to setup your VPN within a VM so you have more control over the network traffic going from it. But I don't know if this might work for what you want to achieve.

 

Do you use Windows server? Then installing the router role on your server might be part of the solution. See picture in spoiler bar.

 

default via 192.168.1.1 dev wlp3s0 proto dhcp metric 600 
10.0.3.0/24 dev lxcbr0 proto kernel scope link src 10.0.3.1 linkdown 
192.168.1.0/24 dev wlp3s0 proto kernel scope link src 192.168.1.107 metric 600 
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown 

Spoiler

 

 

[RileyTheFox]

2 minutes ago, Jarno. said:

 

The only way I can come up with is by modifying your routing table. But this would be tricky as you need to know exactly what the source IP or subnet's are. See example below of my system. They network 10.0.3.0/24 is a virtual network for example which is bridged to wireless interface wlp3s0. In your situation this would go to your secondary NIC and it won't be bridged.

 

Do you use Windows server? Then installing the router role on your server might be part of the solution. See picture in spoiler bar.

 

default via 192.168.1.1 dev wlp3s0 proto dhcp metric 600 
10.0.3.0/24 dev lxcbr0 proto kernel scope link src 10.0.3.1 linkdown 
192.168.1.0/24 dev wlp3s0 proto kernel scope link src 192.168.1.107 metric 600 
192.168.122.0/24 dev virbr0 proto kernel scope link src 192.168.122.1 linkdown 

  Reveal hidden contents

 

 

I use regular Windows 10 Pro.

[Jarno.]

4 minutes ago, EvilCat70 said:

I use regular Windows 10 Pro.

Then you need to set the correct routes within the routing table manually. Command below might help you getting started.

route ADD destination_network MASK subnet_mask  gateway_ip metric_cost

 

[RileyTheFox]

2 minutes ago, Jarno. said:

Then you need set the correct routes within the routing table manually. Command below might help you getting started.

route ADD destination_network MASK subnet_mask  gateway_ip metric_cost

 

What values should I put into the placeholders (e.g destination, subnet etc)

 

Is the destination the OpenVPN adapter? How does this set it so that a specific application uses that adapter and the rest of the system uses my normal adapter?

[Jarno.]

14 minutes ago, EvilCat70 said:

What values should I put into the placeholders (e.g destination, subnet etc)

 

Is the destination the OpenVPN adapter? How does this set it so that a specific application uses that adapter and the rest of the system uses my normal adapter?

Actually I don't really know you might want to read up on this. Got experience creating routes within Cisco routers but not within Windows. But normally you route a network trough a given interface or to the next hop address you won't do this with only one application which makes this more difficult.

 

That is why you want it to be in a VM so you can just route the virtual network trough a given interface making it way easier to get it working. All the traffic that is not within this static route should just route the normal way to the internet like it always did.

 

 

 

 

[Olaf6541]

I dont know how relevant this is, but in my pfsense openvpn server config theres this option:

Maybe this is the option youre looking for? I dont know where you can find this on windows 10 pro...

[jake9000]

The thing with route tables (and split tunneling, which is what you want with OpenVPN) id you need to know in advance the address range to isolate. With peer2peer games this is a pretty difficult task!

[Jarno.]

On 9/28/2019 at 7:18 PM, jake9000 said:

The thing with route tables (and split tunneling, which is what you want with OpenVPN) id you need to know in advance the address range to isolate. With peer2peer games this is a pretty difficult task!

Very true that why you want it at  a different PC or in a VM.

[Nick7]

OP: Yes, you can do that. When you set up VPN, you can set up routes, or what is sent via VPN. Check OpenVPN examples, and you'll see how to set it up. You can do it either on server, so it pushes routing config, or on client itself.

 

So, you can have traffic go for only one IP via VPN, or multiple subnets... and rest via regular public network.