ifconfig alias: File Exists

JohnsoBS at vicksburg.navy.mil JohnsoBS at vicksburg.navy.mil
Mon Oct 25 08:20:43 PDT 2004


-----Original Message-----
From: TM4525 at aol.com [mailto:TM4525 at aol.com]
Sent: Monday, October 25, 2004 4:59 PM
To: JohnsoBS at vicksburg.navy.mil
Cc: questions at freebsd.org
Subject: Re: ifconfig alias: File Exists

In a message dated 10/24/04 11:18:14 AM Eastern Daylight Time,
JohnsoBS at vicksburg.navy.mil writes:

> >Is that new?  You are right, that fixed it, but didn't think 
> I had to do 
> >that before :(
> You get it because the guy who maintains ifconfig didn't have 
> the foresight
> to realize the "alias" should imply a host mask, and also 
> that the guy who
> coded the kernel code didn't think that assuming a host mask was 
> reasonable.
> Welcome to open source. Love it and live with it.
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>To assume makes an ass out of u and me. Ok, that out of the way, the config
>you assume should be coded into ifconfig and kernel is not 100% going to be
>used all the time. In fact I have multiple nets and have multiple netmask
>assigned on the one machine. If you actually READ "man ifconfig" it states
>that this should be set to what you assume it should be. It helps when
>people don't attack things they don't fully understand cause for many it
>might be a person's first view at what you are bashing. Unfortunately also,
>many people aren't smart enough to get a second opinion or to try beyond
>there first try or someone person's like yourselfs comments.

As for the "assume" thing, speak for yourself. Your implication that there
be no defaults is quite asinine. 
If it doesn't work with no netmask specified, then its broken. Its not
to assume that if no netmask is provided, then a host mask (for an alias) is
In the absence of a netmask, the only "assumption" thats reasonable is a 
host mask. 
There are lots of "assumptions" made by ifconfig. It "assumes" that you only
want the interface to have one address (as if you submit an address to 
an interface that already has one it explicitly deletes the other). Its not 
unreasonable to assume that, nor would it be unreasonable to assume that
the intention was to add an alias. It would certainly be safer.
And I "understand" it a lot better than you do. In today's world, "assuming"

the natural mask (which is what ifconfig has done since the beginning of
is wrong most of the time. Just because someone back in the 1970s decided 
to do it that way doesn't make it correct. One of the basic properties of a
default setting is that it should work 

 I find it very wrong to assume anything on a network interface. Assumptions
anything that could open up a security hole are very dangerous. ifconfig has
a far
greater ability than many things to open up security wholes that may get
an improperly setup firewall.  I agree that some assumptions can easily be
and should be but not here.

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