Re: [Openvpn-users] tun Device Error

[John Locke <mail@xxxxxxxxxxxx>]

Hello,

On Tue, 2003-12-16 at 15:05, Ryan Nielsen wrote:
> I have set up two machines with OpenVPN 1.4.3. They are Debian running a 
> 2.4.18 kernel. I used the HowTo on OpenVPN's site to set both machines 
> up. I was able to get the tun device to work for a while, and then it 
> started giving me this error when trying to run: openvpn --config [file]:
> 
I'm new to OpenVPN, but I think I see the problem. Can't explain why it
would quit working, though.

> Tue Dec 16 15:31:40 2003 87[0]: TUN/TAP device tun0 opened
> Tue Dec 16 15:31:40 2003 88[0]: /sbin/ifconfig tun0 192.168.0.187 
> pointopoint 10.0.0.3 mtu 1259

These are going to two completely different subnets. With a tun device,
you need to set up a subnet purely for the VPN, and use two unique
addresses on it--one for each end of the tunnel. So if one of your
existing networks uses 192.168.0.0/24, and your other uses
10.0.0.0/something, choose a third subnet for the VPN.

Set the ifconfig statements to be the reverse of each other on each end
of the connection. So on one side, set:

ifconfig 192.168.43.1 192.168.43.2

and on the other side, set:

ifconfig 192.168.43.2 192.168.43.1

Then you need to figure out your routes, if you're trying to connect to
other computers networked to the other gateway. This would be something
like:

route 10.0.0.0 255.0.0.0 192.168.43.2 (routes all traffic to a 10./8
network through the tunnel to the remote VPN endpoint at 192.168.43.1)

route 192.168.0.0 255.255.255.0 192.168.43.1 (on the other end of the
connection, routes traffic to the 192.168.0.0/24 network through the
tunnel to the 192.168.43.1 endpoint)

If either of these computers is not the default gateway for the LAN,
other computers on the LAN will need to also have the route to direct
responding traffic from the VPN private subnet back to the VPN
gateway--for example, all computers on the 10/8 network will need to
route traffic bound for 192.168.43.0/24 to 10.0.0.3. It also works to
just put this route on the default gateway for that network.

Hope that helps,
-- 
John Locke
Open Source solutions for small business problems
http://freelock.com


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