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Re: ip directed-broadcast

  • From: Jon Lewis
  • Date: Mon Dec 29 13:02:00 1997

On Mon, 29 Dec 1997, Ken Leland wrote:

> I was informed of the following, by the manager that indicated that he 
> handles backbone-to-customer filter policy:
> 
> 1.)   they will not continue to try to trace this. (they had made 
>         some previous unsuccessful efforts)

Strike 1.

> 2.)   they will no longer filter icmp echo reply for me, even though
>         they understand that my link is now useless without that.
> 	They do not have cpu cycles to spare for this purpose.

Somewhat understandable...but perhaps they should have designed their
network a little better and not overloaded their routers to point that one
or few line filters push the CPU over the edge....Strike 2.

> 3.)   they do not see this type of attack very often and don't 
>         consider it much of a problem.

Sure...it causes them very little trouble.  Odds are good their NOC gets
smurfed very rarely.  Strike 3.

> I find this rather perplexing to say the least. Comments?

I don't know about Sprint, but UUNET actually has provisions in their T1
customer contracts for refunds for interruption of service.  Even if you
don't have such provisions in your contract with Sprint, I'd get on the
phone to your sales rep and as high a person as you can get to in their
NOC and let them know that you consider your T1 to Sprint unusable, and do
not intend to pay the next bill...at least no in full.

> This attack is an ongoing problem so I hope it is seen as an operational
> issue. It is beginning to be a chronic problem (4 day duration).  

FDT used to have major problems with smurf attacks...I was getting to be
on a first name basis with most of UUNET's NOC graveyard shift.  They'd
usually put in a temporary filter to stop the attack, though sometimes it
took longer than other's.  What finally stopped the attacks was looking at
who/what was being attacked.  At least in our case, systems weren't being
smurfed just for the heck of it.  Generally, there was something going on
that was (justifiably or not) pissing someone somewhere off.  Make sure
your users and systems are behaving, and the smurfing is likely to stop. 

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