Monthly Archives: October 2018

Android smartphone "Cubot Echo"

+ Very good overall quality compared to cheap price
+ Good display, camera quality and performance compared to cheap price
+ Large 5.0 inch display
+ HDR photography
+ Up to 128 GB micro sdcard, 16 GB preinstalled ROM
+ Plain Android user experience, no annoying modifications or add-ons
+ Cheap price

- Latest firmware only from June 2017 (does not include security update for WPA2 KRACK attack)
- Android 6 - though Android Version 6 still has the second largest user base as of October 2018
(s. https://developer.android.com/about/dashboards/)
- No 4G / LTE support
- A bit heavy

https://www.cubot.net/smartphones/echo/spec.html

Verdict

You can get this Android smartphone for as cheap as 60 EUR. If you can live with the security issues and the missing LTE support, you cannot get more value for your money elsewhere. Especially considering that the upcoming Google Pixel 3 flagship for 850 EUR guarantees Android security updates for only 3 years. You could buy 14 Cubot Echos for that price ...

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Add entropy to KVM virtual guests (Why is key creation so slow?)

Problem

Cryptographic key creation (GnuPG, SSH, etc.) in virtual guests may be very slow because there is not enough entropy.

$ cat /proc/sys/kernel/random/entropy_avail 
7

Solution

Add /dev/urandom from virtual host in virt-manager. Click on "Add Hardware".

Add "RNG" device.

This is what will be added to the qemu xml file in /etc/libvirt/qemu:

<domain type='kvm'>
  ---
  <devices>
    ...
   <rng model='virtio'> 
     <backend model='random'>/dev/urandom</backend> 
     <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> 
   </rng> 
 </devices> 
</domain>

In the virtual guest, install "rng-tools" (Ubuntu 18.04).

$ sudo apt-get install rng-tools

If something goes wrong, the rngd daemon will complain in /var/log/syslog.

Oct 13 22:48:07 guest rngd: read error 
Oct 13 22:48:07 guest rngd: message repeated 99 times: [ read error] 
Oct 13 22:48:07 guest rngd: No entropy sources working, exiting rngd

If rngd is working correctly, check entropy level again.

$ cat /proc/sys/kernel/random/entropy_avail
3162
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