Stop OpenVPN from connecting when on LAN?

calcprogrammer1

I have set up OpenVPN on my home network as well as my parents' home network using two DDWRT-enabled Linksys WRT160N routers. I use it to bridge the two LAN's together and it works great. I decided that I wanted to be able to access the LAN from anywhere else, so I set up another OpenVPN server on my router to log in from anywhere:

[Laptop] <---Internet---> [Router OpenVPN Server] [Router OpenVPN Client] <---Internet---> [Parents' Router OpenVPN Server]

Both routers run DHCP (mine is 192.168.3.1, theirs 192.168.2.1, and netmask 255.255.0.0 so they can see each other). This part works fine, and when I'm away I can see both my home LAN and their LAN (I have a machine back at their house that I wanted to remote into and when I'm visiting I still have access to my LAN server at my house).

However, when I took my laptop back to my house and connected it to my router's WiFi, the laptop took two IP addresses (one on the router's DHCP, one on the OpenVPN server) and could not connect to the Internet. Disabling the OpenVPN connection fixes the problem.

Is there any way to configure OpenVPN so that it does not connect the tap device if it is already on the LAN? My laptop runs both Windows 7 and Ubuntu 12.04, though as of now I haven't set up OpenVPN on Windows.

remote <no-ip redirect to home network> 1194

client 
dev tap0 
proto udp 
resolv-retry infinite 
nobind 
persist-key 
persist-tun 
float 

ca ca.crt 
cert client3.crt 
key client3.key 

ns-cert-type server

wininstaller

Hi,

first of all, I'm a really new to OpenVPN. I am actually still trying to get mine to work, so... :? :roll:

However, I think a possible way to solve the problem would be to modify the OpenVPN server config of the second instance you are running on the router (the one you use from your laptop when connected from outside). Did you specify in that server config file that the OpenVPN server should listen only on the external router address? In this way, the router will only listen for connections from outside and will not assign you an internal IP.

Just a thought. Enjoy the we!! 😃

Mimiko

Did you specify in that server config file that the OpenVPN server should listen only on the external router address?

Yes this is a must, like using in OpenVPN server:

local a.b.c.d

but this will be still a problem if router will forward and masquerade packets comming from inside and destined for a.b.c.d. This must be blocked also.