Enabling default SSH access

In order to enable SSH access after downloading Raspbian Lite without desktop environment and writhing it to SD card you must add empty file called ‚ssh‚ (no extension) on boot drive while your SD card is still connected to your PC. Next place the SD card in your Raspberry Pi and boot.

Login to Raspberry Pi using SSH connection

In command line type with your Raspberry Pi IP address:

ssh pi@xxx.xxx.xxx.xxx

and provide default password raspberry

Change default password

Change password using this command:

passwd

Configure password less SSH access

First make sure that you have keys generated for your client (PC). If you using Cmder on Windows 10 check following directory for files id_rsa and id_rsa.pub

C:\Users\XXXXX\AppData\Roaming\SPB_16.6\.ssh

Next copy the public key

ssh-copy-id pi@xxx.xxx.xxx.xxx

Disable logging with password

For security reasons it is better to disable asscess with password and use only key dependent authentication, so edit the ssh configuration file:

sudo nano /etc/ssh/sshd_config

Find line

#PasswordAuthentication yes

remove comment (# character) and change value to no

PasswordAuthentication no

Now restart the service or reboot the Raspberry

sudo /etc/init.d/ssh restart
sudo reboot

Changing SSH port

This is an optional step, you can change the default port from 22 to something else by editing SSH config file:

sudo nano /etc/ssh/sshd_config

change the port 22 to something else and restart SSH service as in previos

Port 50022

Next restart the ssh service

sudo service ssh restart

Start ssh agent on local machine

eval $(ssh-agent)

Sources

https://www.raspberrypi.org/documentation/remote-access/ssh/passwordless.md

How to Set Up Keys and Disable Password Login for ssh on your Raspberry Pi

https://unix.stackexchange.com/questions/351725/why-eval-the-output-of-ssh-agent

Today it is time to use Samba for USB Drives sharing.

Mounting USB Drive

1. Create new directory where your drive will be mounted

sudo mkdir /media/usbHDD
sudo chmod 744 /media/usbHDD

2. List your storage devices and save UUID of your drive

ls -l /dev/disk/by-uuid/

(Update) more readable command:

sudo lsblk -o UUID,NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL,MODEL
or
sudo blkid

3. Mount that drive to /media/usbHDD, use proper user and group (uid, guid), adjust drive path

sudo mount -o uid=pi,gid=pi /dev/sda1 /media/usb

4. Edit fstab

sudo nano /etc/fstab

and add line with UUID of your drive

UUID=18A9-9943 /media/usbHDD vfat auto,nofail,noatime,users,rw 0 0

5. Verify if drive is mounted

ls -l /media/usbHDD

restart and verify if drive is mounted after reboot

sudo reboot now
ls -l /media/usbHDD

Update:

If you have problems with auto mount you may need to install:

sudo apt-get install exfat-fuse
or
sudo apt-get install ntfs-3g

You may also need to change partition type in command in fstab file from vfat to ntfs

Installing Samba

The process of installation is very simple

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install samba samba-common-bin

Czytaj więcej

In this post I’ll gather all useful commands that I used during my experiments with RPi

Commands:

Lists all attached bulk storage devices

lsblk

List all drives by uuid

ls -l /dev/disk/by-uuid/

Mount drive

sudo mount -o uid=pi,gid=pi /dev/sda1 /media/usb 

you have to use uid and gid in order to delete add new devices.

Automount drive at start-up

sudo nano /etc/fstab

and add

UUID=18A9-9943 /media/usb vfat auto,nofail,noatime,users,rw 0 0

The “nofail” option allows the boot process to proceed if the drive is not plugged in. The “noatime” option stops the file access time being updated every time a file is read from the USB stick. This helps improve performance.
Czytaj więcej

Basically I wanted to test how fast my RPi will heat up under stress with or without heat sinks

How to perform stress test

It is easy with stress application.

Install:

sudo apt-get install stress 

Stress test:

sudo stress --cpu 4

it will span 4 processes that will execute on each of RPi core calculating sqrt function (source).

Constantly measure CPU temperature

Command:

watch -n 1 /opt/vc/bin/vcgencmd measure_temp

This command will print cpu temperature on console each 1 second.

CPU utilisation

You can observe how 4 stress processes are utilising cpu with command:

top

Radiator tests

Cheapest small aluminium radiators under 0.24$ per lot: link

No heat sinks:

• idle: around 50 C
• under stress: up to 82 C
• response on air flow: low decreases maximum temperature by 2-3 C

With heat sinks:

• idle: around 44 C
• under stress: up to 77 C
• response on air flow: good decreases maximum temperature by 7-8 C

Conclusion

I’m a bit disappointed with those small heat sinks, expecting that they’ll lower temperatures more drastically. Using fan that will blows air on them will give better results.