Server and device ip address mapping

pmatil

I'm trying to use the OpenVPN server on my Asus RT-N18U wireless router. The home network is configured as follows:

- There is a firewall / dhcp server at address 192.168.0.1 / 255.255.255.0
- The Asus does not give ip-addresses at all (dhcp disabled), and it's LAN address is 192.168.0.100 / 255.255.255.0
- Asus' WAN port gets a public IP-address via dhcp
- The OpenVPN server's VPN address range is 10.10.0.0 / 255.255.255.0. Push LAN to clients is enabled.

Now, I can connect to the server OK, but I cannot access any other device except the router itself, which is at address 10.10.0.1. So .100 becomes .1. Can this even work? I cannot figure out how the other devices map into the VPN address range. Maybe I need a custom config or different subnet declaration. I can change the Asus' LAN address but the existing router in the network is fixed to 192.168.0.1. So could OpenVPN server work even though LAN address is not the first address in the network?

The router is running linux with OpenVPN server version 2.3.2. I can input custom configuration directives if needed. The system log says:

OpenVPN[]: /sbin/ifconfig tun21 10.10.0.1 pointopoint 10.10.0.2 mtu 1500
OpenVPN[]: /sbin/route add -net 10.10.0.0 netmask 255.255.255.0 gw 10.10.0.2
OpenVPN[]: IFCONFIG POOL: base=10.10.0.4 size=62 ipv6=0

The connecting client gets ip address 10.10.0.6.

Server configuration:
- TUN
- UDP
- Auth mode TLS
- Extra HMAC bidir
- VPN subnet 10.10.0.0 / 255.255.255.0
- Push LAN to clients: YES
- Direct clients to redirect internet traffic: NO
- Respond to DNS: NO
- Cipher: AES-256-CBC
- Compression: adaptive
- TLS renegotiation time: -1

Traffic

Technically, we do not support router devices .. however ..

pmatil wroteThere is a firewall / dhcp server at address 192.168.0.1 / 255.255.255.0

This is the number one worse subnet you can choose ..
You are strongly recommended to find a way to change it to a more unique subnet.
Unique example: 192.168.159.0/24

pmatil wrotebut I cannot access any other device except the router itself, which is at address 10.10.0.1

Well, it is a good start .. but you are going to need to read some docs on this.

pmatil wroteSo .100 becomes .1. Can this even work?

does not "become" but has two ip addresses.

pmatil wroteI cannot figure out how the other devices map into the VPN address range

You need to read our documentation and that of your router and probably openWRT.

pmatil wroteThe connecting client gets ip address 10.10.0.6.

That is good ..

Please read our entire howto:
https://openvpn.net/index.php/open-source/documentation/howto.html