m4gu5

GNU/Linux, BOINC, Programming, Infosec, FOSS, Nerd Stuff

[m4gu5]

HowTo Configure a static ethernet connection in ArchLinux

Assigning a static ip address to your ArchLinux box can be quite a struggle if you’ve never done it before.

This step-by-step tutorial shows you how to set up your ethernet adapter using the following settings:

IP address: 192.168.2.123 Gateway: 192.168.2.1 Name of Ethernet Adapter: eth0

Configure

Obtain a root shell on the ArchLinux machine # su root

Find out your adapter name Execute the following command and write down the name of the ethernet adapter. # ip link show Usually the name is “eth0″ or something like “enp2s0f1″. In this How-To we will use “eth0″ as adapter name. Change it to your needs in the next steps!

Change to the netctl directory and copy the example file for static ethernet configuration # cd /etc/netctl # cp examples/ethernet-static ./eth0

Change the example file to your needs # vim eth0 The following lines are needed for our example configuration. The “ForceConnect” option is used to circumvent any problems on startup. “SkipNoCarrier” automatically applies the settings as soon as the ethernet cable is plugged in. Description='Static ethernet connection' Interface=eth0 Connection=ethernet IP=static Address='192.168.2.123/24' Gateway='192.168.2.1' DNS='192.168.2.1' ForceConnect=yes SkipNoCarrier=yes

Enable the eth0 profile so it will be loaded on system startup # netctl enable eth0

Install ifplugd and enable the service for your interface # pacman -S ifplugd # systemctl enable [email protected]

Check

Start the service or restart the machine to check if everything works.

# systemctl start [email protected] # reboot

[m4gu5]

ODROID-C2 Dedicated Linux BOINC Cruncher How-To

This is a step-by-step Tutorial on how you can use your ODROID-C2 as a dedicated BOINC cruncher.

Check the BOINC project list to find BOINC projects that support Linux on the ARM platform.

In this How-To we use a GNU/Linux host system to write the disk image to the storage media of the ODROID. If you are using another operating system, you have to use alternative methods.

Download & extract Armbian for ODROID-C2

I recommend the lightweight Armbian GNU/Linux distribution for use as BOINC crunching device. The server version does not contain any desktop environment, so no resources are going to be wasted for things we do not need anyway.

Download the server image for the C2 from the following URL: https://www.armbian.com/odroid-c2/

Extract the image

$ 7z e Armbian_5.35_Odroidc2_Debian_jessie_default_3.14.79.7z

Write to MicroSD card

Write the image to your memory card (Device name must be adjusted, of course! You can get the device name of your card by executing lsblk).

$ sudo dd if=Armbian_5.35_Odroidc2_Debian_jessie_default_3.14.79.img of=/dev/YourDevice bs=1M

Flush

$ sync

Set up

Plug the MicroSD card into the ODROID-C2

Boot up the ODROID, blue LED should flash up periodically

Connect to network via Ethernet or Wi-Fi using a static IP address (How-To Wi-Fi)

SSH is active per default with username root, password 1234

Connect to the ODROID via SSH (Change to your IP!) and follow the instructions

$ ssh [email protected]

Add the armhf architecture as it is required by most projects

$ sudo dpkg --add-architecture armhf

Upgrade the system

$ sudo apt update && sudo apt dist-upgrade

Install BOINC & required libraries

$ sudo apt-get install boinc-client libstdc++6:armhf

Start the BOINC client so the config files get created

sudo systemctl start boinc

Set an alternative platform

In order to receive work units from some specific projects (e.g. WUProp), you have to set an alternative platform in the cc_config.xml configuration file as a child of the options element.

$ sudo vim /etc/boinc-client/cc_config.xml

<alt_platform>arm-unknown-linux-gnueabihf</alt_platform>

Enable remote access

You can choose between two options to enable remote access. Either you add every host you want to allow access to remote_hosts.cfg or you enable access for everyone by modifiying cc_config.xml, again adding a child to the options element.

Restricted: remote_hosts.cfg

$ sudo vim /var/lib/boinc-client/remote_hosts.cfg

Unrestricted: cc_config.xml

$ sudo vim /etc/boinc-client/cc_config.xml

<allow_remote_gui_rpc>1</allow_remote_gui_rpc>

(Optional) Set access password

$ sudo vim /var/lib/boinc-client/gui_rpc_auth.cfg

Finish

Reboot to apply the updates

Connect to the ODROID using the IP address you configured. You can connect via BOINC Manager, boinctui or another GUI and then add your projects as normal.

Complete cc_config.xml

The cc_config.xml should look like this when allowing remote access for every host.

<cc_config>  <options>    <alt_platform>arm-unknown-linux-gnueabihf</alt_platform>    <allow_remote_gui_rpc>1</allow_remote_gui_rpc>  </options>  <log_flags>    <task>1</task>    <file_xfer>1</file_xfer>    <sched_ops>1</sched_ops>  </log_flags> </cc_config>

Further configuration

Check the “Notes” section on the Armbian page for the ODROID-C2 to improve the power usage and to disable the flashing blue led if you like.

[m4gu5]

How to easily connect your headless Debian-based box to WiFi

Setting up WiFi on a headless Linux machine can be a pain in the ass. 

Most guides you’ll find online will tell you to insert your network information into wpa_supplicant.conf and execute wpa_supplicant with the proper arguments. This is annoying especially for newbies who first have to find a suitable template, figure out which driver to specify and so on. Additionally, if the adapter disconnects from the access point for whatever reason, with this method it won’t get reconnected automatically.

A much easier way of connecting your CLI only machines to WiFi is via /etc/network/interfaces. This guide will show you how to do it.

This guide is for WPA2-PSK only, because that’s what you should use for your personal wireless network.

The setup

This tutorial uses the following sample data for illustration purposes:

WiFi name: test-wlan

WiFi password: &/(§"$23823asd§$a!0dfAe

WiFi netmask: /24 (255.255.255.0)

Wireless interface: wlan0

Desired, static IP address: 192.168.2.113

Change these values to match your actual data & needs.

Obtaining the Pre-Shared-Key

First you have to create a 256-bit PSK derived from the the WiFi network name (ESSID) and the plain password. You’ll want to do this to avoid saving the plain text password into the configuration file later. Execute the program wpa_passphrase along with your ESSID as argument.

$ wpa_passphrase test-wlan

You will be asked to enter your password for the network. Do this and press enter.

Some data will be created and presented to you. However, we only need the alphanumeric part after “psk” (here: “3af...”), this is the hash. Copy this somewhere.

network={ ssid="test-wlan" #psk="&/(§"$23823asd§$a!0dfAe" psk=3af27aac304d4fbdd22853f3be966fa5942992b701c40d0c8acf34356ee2acb9 }

Do the configuration

Now open the file /etc/network/interfaces with root privileges using your favorite text editor.

$ sudo vim /etc/network/interfaces

The following snippet configures our adapter wlan0. Values required for authentication are wpa-ssid & wpa-psk. Those are your ESSID, wrapped within quotation marks and the hash you created previously, written without quotation marks. Change the values to your needs and save.

allow-hotplug wlan0 iface wlan0 inet static address 192.168.2.113 gateway 192.168.2.1 netmask 255.255.255.0 network 192.168.2.0 broadcast 192.168.2.255 wpa-ssid "test-wlan" wpa-psk 3af27aac304d4fbdd22853f3be966fa5942992b701c40d0c8acf34356ee2acb9

Apply

Either reboot the device or restart the networking service to apply the configuration changes.

Your WiFi adapter should now connect automatically to your network at system start. If the device gets disconnected, it will reconnect as soon as a connection is possible again.

[m4gu5]

BOINC on the Raspberry Pi

With BOINC you can donate your devices spare computing power to science. This blogpost explains how to install and run BOINC on a Raspberry Pi Model B running Raspbian. This guide also works for the Raspberry Pi 2 and can be adopted for any other board that uses an ARM processor along with a Debian based Linux distribution.

What do you need?

Raspberry Pi running Raspbian connected to your local network

Another computer with an active SSH connection to the Raspi

Installation

To install the boinc-client, simply apt-get the package boinc-client.

$ sudo apt-get install boinc-client

The client should be started automatically after install. Otherwise, a manual start is required:

$ sudo /etc/init.d/boinc-client start

Configuration

Set a password

For accessing the BOINC client, a password should be set. Write your password into the file /etc/boinc-client/gui_rpc_auth.cfg. You will need this password when connecting e.g. from the BOINC Manager or via boinctui.

Whitelist remote hosts

In order to be able to connect to the BOINC instance, the hosts from which you will access it must be whitelisted. To do this, insert all IP addresses needed into /etc/boinc-client/remote_hosts.cfg.

$ sudo echo <IpAddress> >> /etc/boinc-client/remote_hosts.cfg

Multiple addresses can be separated by new lines.

Connect

Now you should be all set to connect your manager with the Raspi BOINC instance. When using the BOINC Manager you have to click on File -> Select computer.... Enter the IP address of your Raspberry Pi and the password you set via /etc/boinc-client/gui_rpc_auth.cfg. Click OK. 

Voilà! You should now be connected and able to add projects as usual.

Run

Cooling

When running BOINC on any device, good cooling is mandatory. At least a passive heatsink is required, better active. A good cooling also prevents the CPU from throttling, which would decrease the overall output.

CPU Frequency

If sufficient cooling is guaranteed, the frequency of the CPU can be easily increased. To do this, the values for cpu_freq and cpu_freq_min must be adjusted in the file /boot/config.txt. The following sets the CPU frequency to 900 MHz and the throttled frequency to 700 MHz. This means if a predefined temperature is exceeded, the processor will underclock to this value.

arm_freq=900 arm_freq_min=700

You will have to find out what frequency works best for your use case without overheating the CPU (24/7 or just a few hours a day?).

Monitoring

Query the current CPU frequency

$ sudo vcgencmd measure_clock arm

Query the current CPU temperature

$ sudo vcgencmd measure_temp

Query values periodically by using the watch command:

$ sudo watch -n 1 vcgencmd measure_temp

vcgencmd can also be used to obtain a bunch of other values. To see a full list of possible commands, type

$ sudo vcgencmd commands

Troubleshooting

No tasks are being sent

First, reload the config files manually and see if it works afterwards:

$ sudo /etc/init.d/boinc-client reload

If it still doesn’t work, check the Event log. A common error is that BOINC is not allowed to use the available disk space. You can change this in the Computing Preferences under “Disk and memory”. For dedicated crunching machines I recommend the following settings:

Leave at least 0.1 GB free Use no more than 90% of total

In some cases you may need to tell projects that you are running on an ARM platform. A change in the file /etc/boinc-client/cc_config.xml must be made. Insert the following text inside the root element.

<options> <alt_platform>arm-unknown-linux-gnueabihf</alt_platform> </options>

Then restart the boinc-client and update the project.

$ sudo /etc/init.d/boinc-client restart

[m4gu5]

Don't wake up a programmer

Today I found an excellent article in which the process of programming is compared to dreaming. I rarely agree with as many things as I did while reading this post. Read the blog post here: Programming is Like a Dream

PS: You can improve your "dreaming experience" even more by listening to Trance/relaxing music while coding (My experience).

[m4gu5]

Microsoft Account to get more secure

In a blog post Microsoft recently published, they announce a major upgrade to Microsoft Account. This includes the possibility to enable Two-Factor-Verification in order to be able to log in.

That's a step in the right direction. But Microsoft still has something to do. Example: You can't choose a password longer than 16 characters (Screenshot below). I don't understand why such a limitation is given.