Messages in this thread | | | Date | Fri, 1 Feb 2002 12:57:03 -0700 | From | Andreas Dilger <> | Subject | Re: Continuing /dev/random problems with 2.4 |
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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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