OpenVPN Failing to Make TUN the Default Interface

martingoose

I have been experimenting with using OpenVPN to create a secure VPN connection back home when I use hotel and other public wi-fi. The OpenVPN server is running on a RaspberryPi set up according to the instructions at:
https://tryapi.wordpress.com/2014/10/13/install-latest-openvpn-and-easyrsa3/

I have successfully accessed the VPN server from my Samsung tablet using the android client from:
https://play.google.com/store/apps/details?id=net.openvpn.openvpn

Initially I was able to access the server using PCLinuxOS on my Acer Laptop but this now fails. Now back home I have carried out some tests and it seems that when my initial network connection is wired I can access the server but when it is wireless I cannot. The output displayed as the connection is made is identical except that eth0 is replaced by wlan0.

It seems that the tun0 interface is being created but does not become the default interface when the initial interface is wireless.

Does anyone have experience of this? Is there a shell command to make tun0 the default interface (or is it not that simple)?

Traffic

You probably mean "default route" not interface .. but ..

It will be best if you post your configs please.

martingoose

Traffic wroteYou probably mean "default route" not interface .. but ..

Please excuse my lack of understanding. This is all new to me.

It will be best if you post your configs please.

Client config (with some deletions) is as follows:

client
dev tun
proto udp
remote <my IP> <my port>
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
cipher AES-256-CBC
comp-lzo
verb 4

key-direction 1
<ca>
-----BEGIN CERTIFICATE-----

<Certificate Removed>

-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----

<Certificate Removed>

-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN PRIVATE KEY-----

<Certificate Removed>

-----END PRIVATE KEY-----
</key>
<tls-auth>
-----BEGIN OpenVPN Static key V1-----

<Certificate Removed>

-----END OpenVPN Static key V1-----
</tls-auth>

martingoose

Further to the previous post I have looked at the routing as it exists when connected wired and wireless.

Wired (It works)

unicast 0.0.0.0/1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast default via 192.168.0.1 dev eth0  proto boot  scope global 
unicast 10.8.0.1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast 10.8.0.5 dev tun0  proto kernel  scope link  src 10.8.0.6 
unicast 127.0.0.0/8 dev lo  proto boot  scope link 
unicast 128.0.0.0/1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast 169.254.0.0/16 dev eth0  proto boot  scope link  metric 1002 
unicast 192.168.0.0/24 dev eth0  proto kernel  scope link  src 192.168.0.137 
unicast <WAN IP> via 192.168.0.1 dev eth0  proto boot  scope global

Wireless (Doesn't work)

unicast 0.0.0.0/1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast default via 192.168.0.1 dev wlan0  proto boot  scope global 
unicast 10.8.0.1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast 10.8.0.5 dev tun0  proto kernel  scope link  src 10.8.0.6 
unicast 127.0.0.0/8 dev lo  proto boot  scope link 
unicast 128.0.0.0/1 via 10.8.0.5 dev tun0  proto boot  scope global 
unicast 169.254.0.0/16 dev wlan0  proto boot  scope link  metric 1003 
unicast 192.168.0.0/24 dev wlan0  proto kernel  scope link  src 192.168.0.132 
unicast <WAN IP> via 192.168.0.1 dev wlan0  proto boot  scope global

Looks very similar except for the 'metric'.

Any clues here for those who understand what it all means?

First couple of lines of the client log show the versions of the software in use:

Sat Aug 22 15:30:33 2015 OpenVPN 2.3.5 x86_64-mandriva-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [MH] [IPv6] built on Nov 5 2014
Sat Aug 22 15:30:33 2015 library versions: OpenSSL 1.0.2d 9 Jul 2015, LZO 2.04