OPENVPN Client : unable to resolve dns name when trying to reconnect

papou · Oct 15, 2011, 4:09 PM

Hi !
I use a 2.0-RELEASE (i386) built on Tue Sep 13 17:00:00 EDT 2011

I have an OPENVPN client connected to a VPN provider with a "redirect-gateway def1" for routing all my trafic through the VPN, it work very well, but after 7 or 8 days the connection goes done and try to restart with a loop error : unable to solve dns name of my VPN Provider.
And of course I still want that all my DNS request goes through the VPN
To try to solve that i did the following config in the System->General Setup

DNS Servers
X.X.X.X with use gateway my OpenVPNInterface
X.X.X.X with use gateway WAN

All the Two checkbox are unchecked

But how can i be sure my dns request are always going through the OpenVPNInterface and only use WAN when OpenVPNInterface goes done and try to solve DNS name to restart ? Nslookup don't give you the route used to solve the DNS name. (i use nslookup debug mode with no result)

Thx ;)

papou

papou · Oct 17, 2011, 4:48 PM

@papou:

But how can i be sure my dns request are always going through the OpenVPNInterface and only use WAN when OpenVPNInterface goes done and try to solve DNS name to restart ? Nslookup don't give you the route used to solve the DNS name. (i use nslookup debug mode with no result)

I think i have answered myself the question by using tcpdump on UDP 53 to listen DNS request

tcpdump -n -i myopenvpninterface 'udp port 53'

I also did it in // on my WAN interface
tcpdump -n -i mywaninterface 'udp port 53'

And i saw the following things with this DNS configuration :

X.X.X.X with use gateway my OpenVPNInterface
X.X.X.X with use gateway WAN

I have the two DNS request going in // on the two interface >:(

now with this DNS configuration :
X.X.X.X with use gateway my OpenVPNInterface
X.X.X.X with use gateway None

I have the DNS request going only through OpenVPNInterface :)
and if i restart the OpenVPNInterface the DNS request going through WAN and then through OpenVPNInterface when it become up ;D

So it seems to work as i want with this configuration :D

I now will see if my VPN connexion resolve the DNS when it will restart in few days….

Nachtfalke · Oct 17, 2011, 5:25 PM

Hi,

thanks for your feedback. Please post your results (in a few days).