Re: Specifying names for tap interfaces

[Roger Pau Monne <roger.pau%citrix.com@localhost>]

Christos Zoulas wrote:
> On Jul 5,  3:05pm, roger.pau%citrix.com@localhost (Roger Pau Monne) wrote:
> -- Subject: Re: Specifying names for tap interfaces
>
> |>  Yes, that's nice, but purely cosmetic.
> |
> | It allows users to have persistent interfaces, even after Dom0/DomU
> | reboot, so you can for example graph the traffic a single guest is
> | using, which is not possible now.
>
> You could do the same if you assign a numeric range for them that is
> high enough that will not be re-used. I would also like to mention,
> that the patch is not as simple as presented. Although I have not read
> it carefully, it does not seem to prevent name re-use, so one could
> potentially rename an interface to an existing name, lo0 for example
> and cause all kinds of lossage.

It is not possible to change the name of an interface to an existing 
one, because of this check, this prevents collusion:

if (ifunit(new_name) != NULL)
        return EEXIST;

But a user could do:

ifconfig bnx0 name tmp
ifconfig bnx1 name bnx0
ifconfig tmp name bnx1

Effectively swapping the name of both interfaces.