Desired behaviour of "ifconfig -alias"

[Brooks Davis]

On Fri, Feb 09, 2007 at 01:49:08PM -0800, Jeremy Chadwick wrote:
> On Fri, Feb 09, 2007 at 04:06:56PM -0500, Kevin Way wrote:
> > I recently ran into a bug in the jail startup scripts that caused this
> > command to be executed:
> > 
> >     ifconfig bce0 -alias
> > 
> > It turns out that this command eliminated the primary IP for the device.
> > 
> > man ifconfig defines the behavior of -alias to be:
> > 
> >      -alias  Remove the network address specified.  This would be used
> > if you
> >              incorrectly specified an alias, or it was no longer needed.  If
> >              you have incorrectly set an NS address having the side
> > effect of
> >              specifying the host portion, removing all NS addresses will
> > allow
> >              you to respecify the host portion.
> > 
> > 
> > I can't help but wonder if it would be better behavior to throw an error
> > when no
> > argument is supplied.
> > 
> > The only discussion I found of this in a quick search of the archives
> > was a post in
> > 2004 which noted that the fxp driver actually deletes all IP addresses,
> > but there was
> > no significant follow-up.
> > 
> > Should ifconfig throw an error if no address is supplied?
> 
> My vote is for either 1) an error, or 2) delete all of the aliases
> associated with that interface.  If I had a preference, I'd choose #1.
> 
> I'd argue that -alias doing what you described (removing the non-aliased
> IP bound to the iface) when no inet/inet6 arguments are suppied is
> indeed a bug.

It's way to late to make this change.  This is known behavior and has
been for ages.  If there's a bug it's in the documentation.

-- Brooks
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