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Date:      Tue, 11 Sep 2012 15:37:09 -0700
From:      Xin Li <delphij@delphij.net>
To:        obrien@freebsd.org
Cc:        Arthur Mesh <arthurmesh@gmail.com>, Doug Barton <dougb@FreeBSD.org>, freebsd-rc@freebsd.org, freebsd-security@freebsd.org, RW <rwmaillists@googlemail.com>, =?UTF-8?B?RGFnLUVybGluZyDvv70=?= <des@des.no>, d@delphij.net
Subject:   Re: svn commit: r239569 - head/etc/rc.d
Message-ID:  <504FBD15.8040907@delphij.net>
In-Reply-To: <20120911215212.GA89515@dragon.NUXI.org>
References:  <20120906224703.GD89120@x96.org> <50493480.8060307@FreeBSD.org> <20120911061530.GA77399@dragon.NUXI.org> <504EDC67.9070700@FreeBSD.org> <86sjao7q8c.fsf@ds4.des.no> <20120911205302.27484fd6@gumby.homeunix.com> <20120911200925.GA88456@dragon.NUXI.org> <504FA76A.5000209@delphij.net> <20120911211730.GB89188@dragon.NUXI.org> <504FAB87.3020701@delphij.net> <20120911215212.GA89515@dragon.NUXI.org>

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On 09/11/12 14:52, David O'Brien wrote:
> On Tue, Sep 11, 2012 at 02:22:15PM -0700, Xin Li wrote:
>> On 09/11/12 14:17, David O'Brien wrote:
>>> On Tue, Sep 11, 2012 at 02:04:42PM -0700, Xin Li wrote:
>>>> So if I was to implement the low grade part I'd remove the 
>>>> variable names from the sysctl output at minimum.
>>> 
>>> I've removed the MIB names in my latest diff (based on input
>>> from this thread):
>>> 
>>> +	( dmesg; kenv; df -ib; \ +	    ps -fauxrH -o 
>>> majflt,minflt,nivcsw,nvcsw,nwchan,re,sl,time; \ +	    sysctl
>>> -n kern.cp_times kern.geom kern.lastpid kern.timecounter \ + 
>>> kern.tty_nout kern.tty_nin vm vfs debug dev.cpu; \ +	    date )
>>> \ + | /sbin/sha256 -q | dd of=/dev/random bs=8k 2>/dev/null
>> 
>> Hmm, but this sha256 run will turn the output to 65 bytes (hex 
>> representation of 256 bits of hash output, 64 bytes, and one \n),
>> so, only 256 bits of random data, is that intentional?
> 
> At this point, yes.  If we find better ways of condensing the
> output of the better_than_nothing() commands, we should do that
> instead.  Even with the command list above, its way more than 4k of
> output.  I got about 45k on my test machine.
> 
> You suggested gzip, but I just don't know enough about compression 
> algorithms as they apply in this area to know if we should use
> gzip instead or not.

I don't think I know enough here, unfortunately...

Using gzip is better than not using it though, since 4k worth of
compressed data is better than 4k worth of plain text because of
higher entropy destiny (note that the FreeBSD gzip uses 64K of
input/output buffer for compression by the way so maybe only the first
64K is meaningful if we take only 4k of output).

Cheers,
- -- 
Xin LI <delphij@delphij.net>    https://www.delphij.net/
FreeBSD - The Power to Serve!           Live free or die
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