How to setup VPN server behind NAT?

I have a server that is running Ubuntu 16.

04 and has 2 network cards (eth0 and eth1). Eth0 has a static IP 192.168.20.

Eth1 has a DHCP address 192.5.

I can successfully ping both these addresses from the server's local IP address, but if I try to ping the server's internal IP address from another machine, the ping time out. It works fine if I change my routing settings to use eth0 for the internet traffic.

What I would like to do is setup my router such that the 192.5 address becomes a VPN server and can be accessed by other machines on the same network (including the laptop I am using). I would also like the server to still be accessible from the internet, and I would like it to be able to be accessed from any other machine on the network.

I have tried setting up a simple pptpd server, but it appears the pptp daemon only listens on interface 0 (I have eth0 set as the interface where the daemon listens on.) When I try to enable the pptpd server, it fails: root@server1:~# pppd -x -f /etc/pptpd.conf After some searching online I think I need to change the listen-interface parameter in the configuration file, but I don't know what value I should use. PPTP provides two mechanisms for configuring a remote client. The first is called "transparent mode". This doesn't involve setting up a NAT, so it will work with your existing configuration, but it won't be usable from outside your LAN. The second mechanism is called "masquerade", and this will require you to set up a NAT.

There is a third option called "bridge mode" which will provide a single address on your LAN to be used as a VPN endpoint. This doesn't need you to set up a NAT, but it requires you to configure the IP address of your VPN endpoint on each machine in order to be able to use the VPN. See here for more information.

What is the difference between use NAT and use routing in OpenVPN?

I want to understand the difference between these two.

What I know is that routing is used for internet access and NAT is used for local network access. I also read that in NAT the entire local network can be seen as one big LAN. But if I use routing to forward the traffic for my LAN, where will the routing table (subnet routing) be stored? And what will happen when the server(client) disconnects? What will happen in both the case? "NAT" does not refer to any technology, it just means "network address translation" or "Network Address Translation". So NAT is any solution for translating IP addresses of internal computers to addresses that can be communicated with the outside.

Routing is a software mechanism to forward a packet from its sender to the destination by selecting a route between its source and destination. In your example, you use "routing" to tell the OpenVPN server that it should listen on port 80 on interface eth0 (ie IP address 192.168.10), which is the port for HTTP and HTTPS connections.

You may also use a routing solution to tell the VPN server which other IP addresses it should use to send traffic to other hosts on your LAN. When the server's UDP port 80 is closed, all traffic sent to the external IP address should still be forwarded to the internal IP address that the OpenVPN server listens on. You have to make sure that all your LAN clients use the correct port number and IP address (and the correct subnet).

How to configure NAT in OpenVPN?

Hi, I have setup OpenVPN server for my internet connection.

And it's working fine. But I would like to know how to configure NAT on my computer so that it can access the internet.

Here's what I have done so far: I have opened port 443 in my router's firewall. I have configured OpenVPN to have a static IP address (192.168.2) and have added this IP to my computer's DNS resolver.

I am trying to figure out how to access the internet from my computer. It works fine with the default OpenVPN configuration but when I change my computer's DNS resolver to my router's DNS resolver (192.1), it doesn't work. Can you please help me?

Does OpenVPN use NAT?

I am planning on purchasing a few OpenVPN servers in the next few days.

It is not clear to me if openvpn uses NAT or not. It is also not clear whether my NAT router has to be part of the VPN in order for me to connect, or whether the VPN can do it's own NAT routing.

All my previous research points to no, but I'd like to get some clarification before I go and purchase those servers. Is there any documentation on this? How is it set up in the real world? Is there a way for me to find out by myself? Thanks. EDIT: @RainerB. I understand what you are saying. The main problem is that people want to make a statement such as "This is a very popular software, it can do x, y and z". But they never actually give us the documentation. We just get "We have this very great project, it's all in the code".

And that leads to a lot of people believing things that aren't true. It would be really great if we could just have some simple documentation on all things that are supposed to be so good.

I have been setting up my own OpenVPN-Server with some friends for a while. In the meantime I learned about the basic principles of it and now I am able to explain it to others. You can find some more information at the OpenVPN wiki.e. Here is a small list of all questions I asked myself when I started setting up my first OpenVPN server: Can I use my OpenVPN-server as a VPN Server for my network? How do I know if my VPN-Server is working? Does the traffic leave my home-networks via my VPN-Server? How to I see the traffic leaving my network via the OpenVPN-Server? How do I install the server? How do I set up my client on my phone? How do I configure my OpenVPN-server? What do I need for my router? How do I use the OpenVPN-Server as a VPN Server for my network? How to I access my home-network using the VPN?