NATing Traffic Through VPN Tunnel

TotallyConfused5599

12/6/23, 4:02 PM

I have a Fedora 36 server setup running as a gateway. It forwards packets to a further gateway down the line, which works well. I have taken out a subscription to NordVPN, and have used OpenVPN on the server to connect. The connection works, and tun0 is created.

When I start the VPN tunnel on the server, clients lost connectivity to the outside world. When I stop the VPN tunnel, connectivity is restored. Routing tables on the server (route -n) seem to look okay.

How can I set up the server to route traffic bound for the outside world through the VPN tunnel when it starts? I'm very confused as every tutorial that suggests NAT-ing traffic through the tunnel fails.

When I ping from one of the clients on my local network, this is what I see.

92 bytes from server 192.168.1.3: Communication prohibited by filter
Vr HL TOS  Len   ID Flg  off TTL Pro  cks      Src      Dst
 4  5  00 5400 df62   0 0000  3f  01 ca7a 192.168.1.20  8.8.8.8

Where the server is at 192.168.1.3, and the client is set up at 192.168.1.20.

For additional information:

The VPN is using TCP on port 443
The ethernet adapter on the server is ens34
The VPN is connected through tun0 on the server
The local network is 192.168.1.0/24

I can also verify that traffic originating from the server is directed through the VPN. When I do a "what is my IP" check to the outside world, the IP is different from the ISP assigned to me to my ISP. When I stop the VPN, the IP switches back to the ISP assigned address as expected.

Any help is appreciated.

0 + 1

networking

vpn

gateway

ip-routing

Tero Kilkanen

12/6/23, 4:46 PM

What are the server's firewall rules when VPN is running and when it is switched off?

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: NATing Traffic Through VPN Tunnel

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