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Date:      Wed, 27 May 1998 23:41:40 GMT
From:      mike@sentex.net (Mike Tancsa)
To:        cschuber@uumail.gov.bc.ca
Cc:        freebsd-security@FreeBSD.ORG
Subject:   Re: SMURF in 2.2.5
Message-ID:  <356ca296.243683658@mail.sentex.net>
In-Reply-To: <199805271623.JAA05578@passer.osg.gov.bc.ca>
References:  <199805271623.JAA05578@passer.osg.gov.bc.ca>

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On Wed, 27 May 1998 09:22:50 -0700, in sentex.lists.freebsd.misc you
wrote:

>What about ipfw?  For example, where 123.123.123.0 is your network 
>address,
>
>ipfw add deny icmp from 123.123.123.0 to any
>ipfw add deny icmp from 123.123.123.255 to any

You dont really want to disable all ICMP traffic as it will break some
things...  If you want to prevent pings from flowing through your
FreeBSD box, you can specify something like
ipfw add 4000 deny log icmp from any to any icmptype 0,8 

to stop echo and echo reply...

Also, this does nothing to prevent you from being SMURF attacked.. It
only would help prevent you from being used as a source.  Think about
it, if your network is something like

UPSTREAM  --------DS1 link ---------your gateway

The flood of packets will traverse your DS1 only to be stopped at
"your gateway".. bye bye DS1 bandwidth...

	---Mike

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