On 08/27/2017 04:08 PM, Peter Robinson wrote:
On Sun, Aug 27, 2017 at 8:59 PM, Robert Moskowitz
<rgm(a)htt-consult.com> wrote:
>
> On 08/27/2017 03:31 PM, Peter Robinson wrote:
>> On Sun, Aug 27, 2017 at 6:57 PM, Robert Moskowitz <rgm(a)htt-consult.com>
>> wrote:
>>> I use:
>>>
>>> cat /proc/sys/kernel/random/entropy_avail
>>>
>>> To check on the amount of entropy for creating random stuff like keypairs
>>> with openssl or random nonces and keys for TLS..
>>>
>>> I am using a Cubieboad2.
>>>
>>> With Fedora-Xfce-armhfp-26-1.5-sda.raw.xz I was seeing numbers in the
>>> 3,000.
>>> I don't have that image running right now to get an actual number.
>>>
>>> I just built a system with: Fedora-Server-armhfp-26-1.5-sda.raw.xz
>>>
>>> I am seeing numbers only in the mid 800s:
>>>
>>> [root@C2 ~]# cat /proc/sys/kernel/random/entropy_avail
>>> 866
>>> [root@C2 ~]# cat /proc/sys/kernel/random/entropy_avail
>>> 803
>>> [root@C2 ~]# cat /proc/sys/kernel/random/entropy_avail
>>> 828
>>>
>>>
>>> What is different between these two images? It is the same Cubieboard.
>> Different images have different services enabled by default, is
>> rng-tools intsalled by default on server image?
>
> Just checked and
>
> Package rng-tools-5-9.fc26.armv7hl is already installed
>
> And after running dnf, entropy dropped to 324....
>
>
>
>>> I have also installed rng-tools with some success, but not as much as
>>> haveged.
>> There's a quality difference between HW rng vs haveged which provides
>> entropy but might not be as random as a proper HW rng
>>
> I could boot up the workstation Xfce image I have, but I was kind of hoping
> there was some knowledge here on differences.
>
> Other than workstation running something like haveged, what else could be
> the source of the entropy difference?
Different services consuming the available entropy
OK. that is the basic answer. This is the minimal server. There are
no connections to it. I am using the serial console. It does have
cockpit running by default, but I would hope that is idling and not
eating up things like resources. I should probably disable it, as it is
not something I would use.
Any idea on how I can figure out what is consuming the entropy?
My minimal Centos7-arm images have ~2500 for the entropy value.
thanks