North American Network Operators Group

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Re: Smurfing

  • From: Kevin Houle
  • Date: Mon Feb 16 00:41:32 1998

On Fri, 13 Feb 1998 11:51:29 -0800 (PST)
"Craig A. Huegen" <[email protected]> wrote:

> With Bay Networks, you must set a false static ARP for the broadcast
> address and then it will not send directed broadcasts.  A Bay SE tells me
> that an option to disable directed broadcasts is being implemented and
> will be in a major release expected around April.

The take the false static ARP concept a little further, I've
been advised to use a fake adjacent host entry to accomplish
this. A Bay SE sent this to me today :

"In order to protect a directly connected network from being a 
smurf launch point, you can configure an Adjacent Host for the 
broadcast address (if the network is a /24 than the broadcast 
addresses would be x.x.x.0 and x.x.x.255) with a bogus MAC address. 
This will cause the smurf traffic to be sent to that bogus MAC 
address which result in NO ONE replying to the smurf."

We originally were advised to use a blackhole static route,
but that does not take precedence over a directly connected
route in the route table.