 | | | Problem with /dev/random? - new question. | Problem with /dev/random? - new question. 2004-05-17 - By akonstam@(protected)
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On Thu, May 13, 2004 at 05:55:03PM -0400, Kent Borg wrote:
> On Thu, May 13, 2004 at 02:26:08PM -0700, Vladimir G. Ivanovic wrote:
> > I am not logged in remotely but locally. I've had a "cat /dev/random"
> > running in a GNOME Terminal tab (window) now for several hours while I
> > read mail & surfed.
>
> Eeek!
>
> One of the problems with /dev/random (as opposed to /dev/urandom) is
> that any user can read it, drain all the entropy, and prevent others
> from getting any. As a test it can be interesting, but don't do that
> otherwise. (Don't forget an extra cat left running on a different
> console.)
>
> Kill the cat. cd to /proc/sys/kernel/random and look around.
> Specifically, cat entropy_avail. I am guessing you will see nothing.
> Now cat a few bytes into /dev/random and cat entropy_avail again. Did
> any show up? If so, then things are as I expect, you need to tell
> your mouse and keyboard and other devices to contribute entropy. I
> would have to start searching through kernel sources and googling to
> find out how.
>
> -kb, the Kent who has run off the end of his immediate knowledge.
>
>
> P.S. Did you do a standard install? What strange things have you
> done? (Compile your own kernel? Mess with boot initializations?)
I have only just had a chance to try the above and found the
following:
1. cat entropy_avail returned 4096
2. I cat-ed a small file into /dev/random. The cat just went on with
random characters on screen until I hit crtl-C.
3. cat entropy_avail returned 177
This is not what you said would happen and I am at a loss what this
all means. Any clarification?
--
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Aaron Konstam
Computer Science
Trinity University
One Trinity Place.
San Antonio, TX 78212-7200
telephone: (210)-999-7484
email:akonstam@(protected)
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