Tuesday, December 23, 2014

Fix slow USB mouse response on my Chromium OS

I have a cordless USB mouse Lenovo N50 connected to a MSI X340 laptop with Chromium OS installed on it. The same mouse works flawlessly on a Chromebook Acer C720 but it gets very slow response on the X340 with Chromium OS ArnoldTheBats build. The mouse cursor's movement on the screen always lags that of the actual mouse by noticeable amount of time. I've tried changing the mousing setting in Chromium browser or xset in console but neither worked. However, today I was able to fix it after updating the Chromium OS to the latest build by following the steps below:
  1. Set my own password for root user: Go to Developer Console in Chromium (push keys Ctrl- Alt-F2) and log in as user "chronos" with initial password "password". Then type the following command:
    sudo chromeos-setdevpasswd

    and enter the new password
  2. Become root user by typing the following command:
    sudo su

    and enter the password set in the previous step
  3. Check network status with the following command:
    In my case, the wireless interface wlan0 is not connected under developer console as no IP address is shown under wlan0. I had to connect an ethernet cable to the laptop to get interface eth0 up. 
  4. Update Chromium OS to the latest build with the following command: update_engine_client --update --omaha_url=http://chromebld.arnoldthebat.co.uk:8080/update
  5. (May not be necessary) After the above update is successful, type the following command:
    sudo stateful_update 
    In my case, this command actually failed.
  6. Try updating the system again as the previous command failed:
    update_engine_client --update
    sudo stateful_update 
    No need to supply the –omaha-url any more in future updates. It showed that the update succeeded and system needs reboot.
  7. Reboot the system and now the mouse is as responsive as on the other Chromebook
  8. Reinstall the Flash plugin: the update was 32-bit, so I used the first instruction below with the link http://goo.gl/FrT7Q6

Monday, December 22, 2014

Install Samba 4.1 AD DC on CentOS 7 with yum

CentOS 7's bundled Samba 4 does not provide Active Directory (AD) Domain Controller (DC) functionality due to the incompatibility between the Kerberos 5 libraries used by a Samba 4 AD DC (Heimdal) and those by RHEL/CentOS (MIT). However, Samba 4 binaries (rpms) compiled with Heimdal Kerberos library for CentOS 7 can be obtained from the Sernet Samba repository without the need of compiling Samba from its source code.

To download the rpm files with yum, a user account is necessary at the Sernet Samba repository. Signing up for a user account at Sernet is totally free and can be done in a minute. Upon successful registration, one can log into the portal and obtain a yum repo file with his username and password embedded in the repo URL. The repo file can be copied to /etc/yum.repos.d and one can then use yum to install the necessary rpms for a Samba 4 AD DC on CentOS 7.

If the bundled Samba 4 was installed in the system, remove it with yum first.
 yum remove samba*
The following Samba 4.1 rpms can then be installed from Sernet on CentOS 7 to enable a AD DC

If there is existing Samba 3 NT4-style domain, it can be upgraded to AD type domain with samba-tool, which is installed as part of the packages above. The following Samba Classic Upgrade wiki guide provides excellent instructions on the upgrade. For simplicity,  one can use Samba 4's built-in DNS server for the AD DC. After the upgrade is complete, start the AD DC by
service sernet-samba-ad start
and test it following this guide.

Thursday, December 18, 2014

Value phones and inexpensive mobile family plan with 4G LTE data

A few smart phones that support 4G LTE data on Sprint's network were on sale with reasonable prices such as LG Optimus F3, LG TributeLG VoltHTC Desire 510 or Nokia Lumia 635. Their screen resolutions may not be full HD, but they have decent performance at their price range and in my opinion, they are great phones for Ting, Sprint's MVNO that has inexpensive mobile family plan.

On Ting, minutes, messages and data are pooled and shared between devices under the same account. You can have as many devices as you want on one account and each device costs $6 per month. There’s no premium charged for a mobile family plan and there isn't any weird line items on the monthly bills besides the taxes & regulatory fees. For example, to have 4 devices share 1000 minutes, 2000 global messages and 1 GB of 4G LTE data would have a total cost of $69/month plus taxes & regulatory fees at Ting, which is below $20/month per device. The 4G LTE data can be bumped to 2 GB for $10 more. At $79/month, it is still less than what I used to pay for only one device with 2 GB data at Verizon.

Most Sprint phones including these LG ones can be activated on Ting with the built-in hands-free activation after a Carrier Reset ##72786# (##SCRTN#). No flashing is necessary at all and you may also enjoy the 4G LTE data speed instantly with this phone that is not available from Page Plus or with a flashed device. If that doesn't sound good enough, Ting has started testing service on a GSM network since February 2015, which will allow both CDMA and GSM devices coexist under a single account and share a single pool of minutes, messages and megabytes.

What makes it even better is that Ting is giving out $25 credit for trying their service. The credit may be adequate for a month's free trial with Ting on one device. Click on this link to receive the promotion for $25 credit, which will show up upon successful activation.