[ot] internal ip address

Glenn Steen glenn.steen at gmail.com
Sat Feb 9 09:32:44 GMT 2008

On 09/02/2008, mikea <mikea at mikea.ath.cx> wrote:
> On Thu, Feb 07, 2008 at 09:52:10PM +0100, Glenn Steen wrote:
> > On 07/02/2008, Matt Kettler <mkettler at evi-inc.com> wrote:
> > > Glenn Steen wrote:
> > > >  For the
> > > > vast majority of organizations, this is a very minor threat, not worth
> > > > breaking RFC...
> > >
> > > Like.. gmail?
> > :-)
> >
> > > Received: by wa-out-1112.google.com with SMTP id m16so1283782waf.14
> > >
> > > Actually, AFAIK, that doesn't actually violate the RFCs.. you MUST add a
> > > Received: header, but I don't see anything in 2821/2822/1123 requiring you to
> > > add a from clause.
> > Ah, but the "breakage" is in _removing_ a Received line added by
> > another SMTP server, be that internal or not... Hm, maybe I'm an
> > idiot, and the original question was just about the Received line
> > added by the MS gw... Sigh. Just goes to show one shouldn't try to do
> > more than three things simultaneously (I got my new DB servers today,
> > or rather the storage and racks... as a surprise "here we are, four
> > workdays early.... Where should we put them?" kind of thing, on a busy
> > day...). Sorry, might've be me typing without much afterthought.
> >
> > > > I'm not saying you're wrong, just that it is ... really minor...
> > > > compared to a lot of other email-related threats:-)... Yes, you can
> > > > counter with "your generalization is bigger than mine"... I know I do
> > > > it too...:-)
> > > >
> > > > On the whole, I see very little _real possibility_ of damages from this.
> > > > It is a leakage, yes.... but negligible in most cases. that's MHO ate least:-).
> If it is _Vital_ to keep the shape of the internal network hidden,
> then the leakage is a problem. Otherwise, it's just another piece of
> the puzzle to be tacked up on the wall. Intelligence organizations
> make their livings by putting together such puzzles. You have to make
> a decision about how much of the puzzle you're comfortable having on
> the wall. It almost always is more than you know is on the wall.
True, but most of us do not contend with ... organizations that have a
LOT of money to spend on things like these:-). But as the scout
says..... :-)

> > > I would agree in most cases it is very minor or negligible. I never said this
> > > applied to most, or even very many people.
> > See above, me reading too fast:-).
> > I tend to react to "security by obscurity" or "the auditor said this
> > is bad for everyone" kind of arguments, where one hasn't done any form
> > of risk assessment...  so that was probably what got me going:-).
> I lost absolutely all respect for the external auditors hired by our
> internal auditing group for an IT audit when one of them:
> o       handed me a CDROM and told me to "boot" our very large IBM
>         mainframe computer from it; and then
> o       refused to believe that I couldn't "open" the NETBEUI port on the
>         mainframe for him.
> The IBM mainframe doesn't "boot" from CDROM, but from very large disk.
> There is not an IBM-supplied listener for NETBEUI, and we don't run
> one.

Been there, done that too.

> These, unfortunately, are the sorts of things that one gets from
> the run-of-the-mill auditors, who download a checklist and run down
> it, one question at a time, one size fits all.

Yeah, but OTOH some auditors actually know what they're about. It's
just a bit frustrating that one cannot choose which auditor you
get:-):-). We do internal audits about once a year, were we choose a
trusted firm, with really good auditors. And once a year we get the
other kind foisted on us "from above". Sigh.

> > > My only point was the "if it's unroutable, you can't hack it" argument isn't a
> > > very complete view of network security.
> > Quite true.  As usual,I find we're in violent agreement (of a
> > sorts:-). I truly value your comments.
> OTOH, if you don't route it, they can't get to it directly, which may
> satisfy your needs. Preventing information leaks, whether direct or
> indirect, overt or covert, is a *much* knottier problem, and one that
> is in the general case insoluble. An air-gap firewall and TEMPEST
> shielding to NACSIM 5100A or better is -- or so the government hopes
> -- at least a good start.

Yeah, but still.... an insider with some knowledge (or equally bad,
without....:-) will defeat most things...:-(

-- Glenn
email: glenn < dot > steen < at > gmail < dot > com
work: glenn < dot > steen < at > ap1 < dot > se

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