ICMP/ Firewall issue

[Stephen Carville]

On Thu, 19 Oct 2000, Peter Svensson wrote:

-
-On Thu, 19 Oct 2000, Igmar Palsenberg wrote:
-
-> Another case of an admin that thinks that blocking ICMP will make things
-> secure. Well, it won't. Blocking ICMP echo makes sense to me, the rest
-> doesn't and get's you into trouble sooner or later.
-
-There are others as well. Routed ICMP redirects are nonsensical for
-example, at least from outside your net. 

There is also a well known DOS attack that can be made against NT/9X that
uses ICMP redirects:

http://www.securityportal.com/list-archive/bugtraq/1999/Mar/0041.html

It's pretty old (and I think SP6 fixed it on NT) but probably a lot of
machines are still vulnerable.

-- 
--Stephen Carville
Network Engineer
714-952-5687
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The triumph of persuasion over force is the sign of a civilized
society.
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