Desired behaviour of "ifconfig -alias"

JoaoBR joao at
Tue Feb 13 08:52:39 UTC 2007

On Tuesday 13 February 2007 04:57, Oliver Fromme wrote:
> Kevin Way wrote:
>  > Oliver Fromme wrote:
>  > > But you called it "confusing".  That's just your personal
>  > > perception.  It doesn't mean it is confusing to everybody.
>  > >  
>  > If asked what -alias does, would you really reply "it removes the
>  > primary IP,
>  > while leaving the alias?"  Be honest here.
> No, I wouldn't answer that, because there is no such thing
> as a primary IP.  All IPs on an interface are equal.  The
> term alias exists only for historical reasons, and it's
> clearly becoming obsolete.

my dear friend I really do not know why you insist on writing this again and 
again. Firstable it is wrong what you say. IP Aliasing is a correct and 
perfect term, used since it is possible to set more then one IP and people 
use it all over the world, in simple networks and specially in hosting 
environments. So it probably never will become obsolete because firstable it 
is THE word in use everywhere, it is grammatically correct and it is easy to 

It does not exist for historical reasons. It is part of IP history and an 
important one, exist because it is in use and so it will stay with us - in 
all OSs ... and almost all languages it is understood as it is - perfectly by 

The only correct thing you say here is that all IPs are equal - and - nobody 
EVER said something different.

Aliasing does not say anything about priority of the Ip it is simply related 
to the time the interface was set with the IP so the first IP is the one 
which was set first and the first alias is the one which was set after.

So by common sense alias describes an additional IP address which was add to 
an already existent address. Otherwise it would not be an alias. 

This understanding, which is completely correct, makes it wrong that "ifconfig 
nic -alias" removes an IP address which is unique on this interface. At least 
when done without warning. 

And also makes it wrong to remove the IP which was set first on this interface 
since it is not an alias by common understanding even if it is equal in 
technical functions.

Then, at the end it is perfectly ok when people say primary address because it 
might be for them THE address of THEIR machine. This is manner of speaking 
and they are probably fully aware of that the other IPs are equal. 

And so this must be bethought, you can not run against common sense even if 
there might be something not exactly expressed. By all respect, you are 
running against the wall here.



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