Solution: Re: Huge smurf attack

Dean Anderson dean at
Tue Jan 12 19:31:07 UTC 1999

Actually, I think all major providers use automatic provisioning systems
which generate router configs. They don't need to rely on router vendors to
set particular defaults.  If all major providers made sure their
provisioning systems turned off directed broadcast, a lot of the problem
would go away.

So "Router defaults" is a lame excuse for ISP's.  Even little ISP's have a
list of things they have to setup, (eg ip classless, subnet zero, etc)
which have "legacy" or otherwise inappropriate defaults.

And yes, some customers may in fact want or need directed broadcasts on.
For example, if they are subnetting. In that case, you change it for them.
I tell our customers certain things are turned off by default, and if they
really want it on, they will need to ask.

Of course, the problem remains that some smurfers are undoubtedly on this
list, possibly working for major providers. (This is my guess as to source
of the 10.x smurf amps.) 


At 02:05 AM 1/12/1999 -0500, Brandon Ross wrote:
>On Mon, 11 Jan 1999, Daniel Senie wrote:
>> The proper answer to this is to disable directed broadcasts on the
>> routers themselves. It'd be helpful if routers came out of the box with
>> this feature disabled by default. Perhaps folks should talk with their
>> router vendors of choice and ask for this change. I have submitted a
>> draft into the IETF process to require this change, updating RFC 1812
>> (router requirements).
>I'm happy to say that progress is being made in this area.  When a vendor
>comes to us for the first time, one of things I tell them is that we will
>not buy their hardware until they ship with directed broadcast disabled by
>default.  We've had a lot of success in this area, we'd have even more if
>others would do the same.
>Brandon Ross            Network Engineering     404-815-0770 800-719-4664
>Director, Network Engineering, MindSpring Ent., Inc.  info at
>                                                            ICQ:  2269442
>Stop Smurf attacks!  Configure your router interfaces to block directed
>broadcasts. See for details.
           Plain Aviation, Inc                  dean at

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