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Re: [Openvpn-users] setting up TAP


  • Subject: Re: [Openvpn-users] setting up TAP
  • From: "Tom Cook" <tom.k.cook@xxxxxxxxx>
  • Date: Fri, 26 Oct 2007 09:59:41 +0930

On 10/26/07, Jeff - <unix_core@xxxxxxxxxxxxx> wrote:
I'm having many unsolvable problems using tun so I thought I'd try tap.

After I run the bridge_start I see br0, eth0, and tap0

The br0 now has an IP address but the other 2 do not.  Is this normal?

Yep, that's right.  br0 is a virtual ethernet interface that combines the eth0 and tap0 physical interfaces.  Only br0 gets an IP address.

When I run OpenVPN on the server and try to connect to it I get an error writing to UPDv4.  Network is unreachable (code 101)

I am no expert here, but it sounds as though you are trying to route the VPN transport traffic over the VPN itself.  Try connecting and then look at the output of 'route -n'.  Check that there is not a default route that puts traffic over the VPN.  If there is, figure out where it is coming from and disable it.

What am I missing?

Also on reboot I don't have the br0 or tap0 anymore.  Do I have to manually get bridge_start to run on bootup?  I'm using debian 4.0

I do this on a debian 4 system.  In /etc/network/interfaces I have this stanza:

auto br0
iface br0 inet static
        address 192.168.2.1
        network 192.168.2.0
        netmask 255.255.255.0
        broadcast 192.168.2.255
        bridge_ports eth1

This means:  Set up a bridge interface br0 with the static address 192.168.2.1 and make it incorporate the eth1 physical interface.  The 'auto br0' line means to bring it up when the system boots.  I then use a script run with the --up option to openvpn to execute 'brctl addif br0 tap0' so that the tap0 interface is added to the bridge when it becomes present (ie. when the VPN is up).

Cheers,
Tom