Great Circle Associates Firewalls
(April 1995)
 

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Subject: Re: Feeping Creaturism in routers (was Re: Response to Satan)
From: lavondes @ tidtest . total . fr (Michel Lavondes)
Date: Tue, 4 Apr 95 11:36:55 BST
To: richardt @ remarque . berkeley . edu (Richard Threadgill)
Cc: firewalls @ greatcircle . com (fw)
In-reply-to: <9790 . 796942264 @ remarque . berkeley . edu>; from "Richard Threadgill" at Apr 3, 95 1:51 pm
Reply-to: lavondes @ tidtest . total . fr

Richard Threadgill wrote :
> 
> [snip]
>  
> This is the strongest reason to not run ntp on your firewall router.
> Why do you consider the incoming ntp stream trustworthy?  (Not to cast
> doubt upon the NTP project, but there are *lots* of interesting attacks 
> on authentication systems which depend on perverting their clock).  I would
> strongly recommend that if you are planning on using clock-based
> authentication schemes (eg, kerberos), you make sure that the clock is
> fundamentally internal. An atomic or radio clock on your premises is fairly
> unlikely to be compromised; an external ntp clock is not so blessed.
> 

What bothers me most is that (according to the docs - I didn't try it) NTP
is *enabled* by default.
-- 
Michel Lavondes          |It's is not, it isn't ain't, and it's it's, not its,
lavondes @
 tidtest .
 total .
 fr|if you mean it is. If you don't, it's its. Then too,
Phone : +33-1-4135-4198  |it's hers. It isn't her's. It isn't our's, either.
#include <disclaimer.h>  |It's ours, and likewise yours and theirs.


References:
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From: pc @ sunbim . be (Philippe Cayphas)
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From: "Steven M. Bellovin" <smb @ research . att . com>

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