Desired behaviour of "ifconfig -alias"

sthaug at sthaug at
Tue Feb 13 19:03:09 UTC 2007

>  > In that situation, wouldn't deleting the primary IP 
>  > cause connection issues for the rest of the IPs?
> No.  I can delete _any_ of the above IP addresses, and the
> others would still work perfectly fine.  I already did
> things like that (on a different machine).
> As for outgoing connections:  It is true that the kernel
> picks a random matching IP address to be the source IP,
> which happens to be the first one, but that's just as
> coincidence as "-alias" picking the first one if none
> is given.  ;-)

If it is indeed true that the kernel picks a *random* IP address for
the source IP, I'd have to say that's not at all good enough.

I'm all for being able to use the same netmask for several addresses
in the same subnet (I have asked for this before) - but the source IP
used by traffic generated from the host itself *must* be predictable.

Steinar Haug, Nethelp consulting, sthaug at

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