North American Network Operators Group

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Re: Firewall stateful handling of ICMP packets

  • From: Owen DeLong
  • Date: Wed Dec 03 19:00:56 2003

Actually, any halfway decent firewall allows you to permit certain ICMP
type codes while rejecting others. Not a perfect solution, but, for the
most part, there aren't a lot of fragmentation-needed exploits running
around. (In fact, I'm hard pressed to imagine how a Frag needed packet
for an invalid session could do much of anything).


--On Wednesday, December 3, 2003 5:12 PM -0500 Sean Donelan <[email protected]> wrote:

You could drop ICMP packets at your firewall if the firewalls properly
implemented stateful inspection of ICMP packets.  The problem is few
firewalls include ICMP responses in their statefull analysis.  So you are
left with two bad choices, permit "all" ICMP packets or deny "all" ICMP

If it wasn't crypto-signed, it probably didn't come from me.

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