Re: ICMP (was: daily internet traffic report)

[Ron DuFresne <dufresne () winternet com>]

Frank,

Question back at you sir;  Does OS fingerprinting rely soley upon ICMP
leakage?  I'd thought I saw a number of papers that related to OS
detection from the incentricities of TCP/IP stacks of the various OS',
like papers by Fydor, documented in phrack, etc.


Thanks,

Ron DuFresne


On Sun, 17 Oct 2004, Frank de Wit wrote:

> I thought I asked a question ; the answer 'yes' should have been
> sufficient ;-)
> Just joking, let's ask two other questions:
> -when you read about ICMP fingerprinting (see Ofir Arkin's great articles)
> -and you see tools like Xprobe and a lot of other OS-fingerprinting tools
> I might be wrong, but:
> a) do you still think ICMP is a good thing in relation to security (by
> obscurity)?
> b) why would you need ICMP from the internet to your perimeter/DMZ-devices?
>
> Hojje, Frank
>
> Willem Koenings wrote:
>
> > > are they?
> > > do you remember 'firewalking'?
> >
> > sorry, but firewalking is not icmp-only technique and don't
> > use full range of icmp types/codes.
> > by firewalking you use tcp or udp packets (depends, which
> > protocol acl you want to study) with one bigger TTL than
> > target and monitor results via icmp type 11.
> >
> > if you really afraid firewalking, then instead of closing
> > down all icmp you can close down only type 11. and nat
> > firewall protects you from firewalking anyway.
> >
> > what i want to say? blindly closing down things is easiest
> > thing to do. but doing so you are not on the top of the problem
> > and you don't control things. get down to the problem and fix
> > things. there's one too many black hole routers in the world
> > and availability is also an security attribute.
> >
> > al the best,
> >
> > W.
>
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