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    SubjectRe: Continuing /dev/random problems with 2.4
    On Feb 01, 2002  13:38 -0600, Ken Brownfield wrote:
    > Of course, in my case deleting the /dev/random character node still
    > doesn't allow entropy to drain in (after at least a month) so I suspect
    > the kernel's entropy generation would be sufficient if it didn't
    > artificially stall or drain from within the kernel.

    Hmm, you may also need to delete /dev/urandom too. Reading from
    /dev/urandom will also deplete the entropy pool just as much as
    reading from /dev/random. The only difference is that /dev/random
    will block if there aren't enough bits as requested, while reads
    from /dev/urandom will happily continue to return data which isn't
    "backed" by any entropy.

    You could also enable debugging in drivers/char/random.c to see what
    is going on (it may be very verbose). You could even change the one
    message in extract_entropy() to include the command name, like:

    DEBUG_ENT("%s has %d bits, %s wants %d bits\n",
    r == sec_random_state ? "secondary" :
    r == random_state ? "primary" : "unknown",
    current->comm, r->entropy_bits, nbytes * 8);

    (not sure of exact usage for current->comm, but you could use ->pid
    instead).


    Note that even traffic over the network will deplete your entropy
    pool, because it is using secure_tcp_sequence_number() and secure_ip_id().
    Also, using SYN cookies appears to increase the amount of entropy used.

    Cheers, Andreas
    --
    Andreas Dilger
    http://sourceforge.net/projects/ext2resize/
    http://www-mddsp.enel.ucalgary.ca/People/adilger/

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