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Thread: Entropy pool never grows...

  1. #1
    Junior Member Newbie
    Join Date
    Jan 2006
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    2

    Default Entropy pool never grows...

    This is causing major issues when running programs that need entropy. Programs just 'hang' and wait for more to be created.

    A good example is, if i load the apache mod auth_digest and start apache , only the parent process is created and child processes are never spawned, the startup process just hangs on "[Tue Jan 03 16:31:04 2006] [notice] Digest: generating secret for digest authentication ...".
    Digest needs entropy.

    I have never encountered a system when entropy was never gathered so, im guessing this is a side effect of the vps envirement.

    Anyone knows of a workaround or a patch or any fix for this?

  2. #2
    StephenAtSpry
    Guest

    Default

    The entropy pool is most commonly filled with random data coming in from Keyboard input, or Mouse input. Many servers suffer this problem since they usually sit in nice air-conditioned rooms for months at a time without anyone ever needing to plug a keyboard or mouse in.

    One workaround is to use /dev/urandom instead. Even though it's not a true random number generator like /dev/random, it's got enough randomness for most applications.

    You could also submit a trouble ticket through our support section (https://www.spry.com/support/myaccount/login.php) with your account details so we can identify the system affected and start generating some entropy.

    --
    Stephen Koenig
    Spry Hosting Support

  3. #3
    Junior Member Newbie
    Join Date
    Jan 2006
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    2

    Default

    Thx for the quick reply.

    I read somewhere that there is a way to use disks and network connection to generate entropy, i just never found a document explaining how...

    I will try to see how to use urandom instead (gotta read a bit :P ).

    If i can't work it, ill open a ticket like you suggested.

    Thank you.

  4. #4
    Junior Member Newbie
    Join Date
    Jan 2006
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    3

    Default

    Stephen was kind enough to shine the light on how to fix this problem for SVN 1.1.4 on the Debian 3.1 Webmin VPS (well, really it's a workaround for the stable branch of Debian 3.1 Sarge). As root you can relink /dev/random to point to /dev/urandom, which is good enough for SVN purposes. For other purposes, consider the lag of using /dev/random while waiting for entropy if you need lots of random numbers ... /dev/urandom is much faster in general.

    Of course, if you really need /dev/random, this isn't good enough, but I don't really need it so far. Stephen has indicated that this issue will be addressed at the VPS level, so meanwhile this is a transparent solution for my Debian VPS.

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