[PLUG] rngd

Eric Wilhelm enobacon at gmail.com
Mon Sep 28 19:09:35 UTC 2009


# from Carlos Konstanski
# on Sunday 27 September 2009 19:00:

>rngd is helping, but even it seems to require some hardware signals to
>produce entropy.

What is currently feeding your /dev/hwrng?  Is the hw_random module 
loaded?  From my reading, rngd is only for bridging hw_random into 
the /dev/random, so you need to already have rng hardware on the 
machine.

>This machine does not get any keyboard or mouse action

The network card, disks, and other drivers also contribute entropy.

> and it uses urandom to generate each new sessionid.  Without some
> source of entropy, urandom would run dry.

/dev/urandom won't ever run dry, though it will become somewhat weaker 
if it has used up all of the entropy.

"The read-only file entropy_avail gives the available entropy. Normally, 
this will be 4096 (bits), a full entropy pool."

  cat /proc/sys/kernel/random/entropy_avail

"Normally" apparently occurs only inside a concrete box.  I think all of 
those ssh sessions are using my entropy... I've only got ~3600 bits.

--Eric
-- 
Anyone who has the power to make you believe absurdities has the power
to make you commit injustices.
--Voltaire
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