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Re: [nsp] known networks for broadcast ping attacks
From: root () gannett com
Date: Wed, 30 Jul 1997 17:35:23 -0400 (EDT)

On Wed, 30 Jul 1997, Systems Engineer wrote:

Well ever since this but was introduced to the outside world,  I have
since modified my present Firewall (ipfwadm v2.3.0) to accomodate.

type  prot source               destination          ports
deny  icmp 0.0.0.0              0.0.0.255            any
deny  icmp 0.0.0.255            0.0.0.0              any


My rule is:

deny icmp   0.0.0.0 0.0.0.0 any

With perhaps specific permits above that for devices that I find have
a legitimate need for ICMP (be it unreachables, or echo/echo reply).

I was wondering more if there were a good reason, other than for dial-up 
users who may need connectivity checks, to allow any ICMP in, or ICMP to 
say anything more than a terminal server's address range and certain hosts.

Hence my prior discussion on ping-mapping netblocks, and its lack of
applicability to the number of hosts on my network.

Paul
-------------------------------------------------------------------------
Paul D. Robertson
gatekeeper () gannett com



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