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| Subject: | Re: Removing ping/icmp from a network |
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| Date: | Tue, 25 Mar 2008 16:04:35 -0400 |
On Tue, Mar 25, 2008 at 3:39 PM, Fabio Fagundes <fabio.fagundes@gmail.com> wrote:
Hi all, Please consider the risk of an intruder using ICMP as a Covert Channel (http://en.wikipedia.org/wiki/Covert_channel). Should one configure corporate routers to inspect and to rewrite ICMP packets to avoid / reduce this risk ? Regards, Fabio.
ICMP packets are fairly small and transparent and by adding any additional information to them would make them malformed and obvious. Given that ICMP traffic can easily stand out from other traffic, an intruder would probably be more likely to utilize TCP and a common service, such as SSL. For the security of my network, I would be more inclined to monitor for excess or malformed ICMP traffic instead of blocking it. -- Mark Owen
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