Setting up TAP interface at boot?

[Jesse Sheidlower]

Where's the right place to set up a TAP interface at boot
time? When my system's up, I usually run "tunctl -t tap0" as
root, but I'd like this to be created automatically. I do
have an entry in /etc/network/interfaces to configure this:

auto tap0
iface tap0 inet static
address 192.168.5.1
netmask 255.255.255.0

but this won't work if the interface doesn't exist, so I end
up having to do everything by hand.

Thanks.

Jesse Sheidlower

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[Boyd Stephen Smith Jr.]

On Sunday 18 January 2009, Jesse Sheidlower <jes...@panix.com> wrote
about 'Setting up TAP interface at boot?':

>Where's the right place to set up a TAP interface at boot
>time? When my system's up, I usually run "tunctl -t tap0" as
>root, but I'd like this to be created automatically. I do
>have an entry in /etc/network/interfaces to configure this:
>
>auto tap0
>iface tap0 inet static
> address 192.168.5.1
> netmask 255.255.255.0
>
>but this won't work if the interface doesn't exist, so I end
>up having to do everything by hand.

Create and statically configure the device during the post-up of the
interface it depends upon. For example, I have a OpenVPN that I want to
come up on eth0. I added the line "openvpn $vpn_name" to the
configuration for the eth0 device.

If you are not doing openvpn, you may have to write your own script and use
the normal /etc/network/if-up.d interface.

If this is something to do with virtualization, so may want the device
create (and configure) script attached to the "lo" device.

If you are happy with having to run a command as root to create the device,
you could also run "ifup tap0" immediately after that command to save a
little manual work.
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[Andrew Malcolmson]

Jesse Sheidlower wrote:
> Where's the right place to set up a TAP interface at boot
> time? When my system's up, I usually run "tunctl -t tap0" as
> root, but I'd like this to be created automatically. I do
> have an entry in /etc/network/interfaces to configure this:
>
> auto tap0
> iface tap0 inet static
> address 192.168.5.1
> netmask 255.255.255.0
>
> but this won't work if the interface doesn't exist, so I end
> up having to do everything by hand.
>
> Thanks.
>
> Jesse Sheidlower
>

To bring up a TAP interface, optionally readable by a non-root user, do:

iface mytap inet static
address 10.0.3.1
netmask 255.255.255.0
pre-up /usr/sbin/tunctl -u username -t mytap