RaspPi Check

Volumio Community Forums Vox Populi
1

Hi to all!
I don’t know if this is the right subforum for my question but anyway…

Can I make RasPi Check (Android app) to work with Volumio?
I know that SSH is disabled. I don’t know how to enable it.
The volumio/volumio or root/volumio options for user name and password do not work with RasPi Check.

I just want to have the information of the app about my RPI. CPU load, temperature etc…

I would appreciate any help!
Thank you

2

You can enable ssh by going to the http://volumio.local/dev page
UID/PWD are as you already mentioned

3

Thank you!
I am enabling SSH but still can not have root access to volumio.
Still both usr/password options do not work with RasPi Check

After enabling SSH on the dev page should I do something more?
How do I save?

Thank you

4

May be in this case I need a sudo password?
If yes what is it?
Thnx

5

volumio

6

No luck… unfortunately!
It should be volumio/volumio/volumio?

After enabling SSH should I save it somehow?

7

If anybody has some idea how to make raspi check work I would appreciate it!!

Thank you.

8

You might have to re-boot after.

Cheers.

9

I think Raspi Check might look for a particular utility that’s present on Raspbian, but not on Volumio.
It’s also likely that it might need root ssh access, which on volumio is not enabled, nor can be enabled (for security reasons).
If you can ask Raspi Check developer what this app looks for, then we might guide you better

10

I did have a quick look at this earlier in the week. The app uses ‘vcgencmd’, which does actually get installed with Volumio, but I could only get it to work under ‘sudo’. Raspicheck needs the user to access it as non root. I did read somewhere that this should work if the user is a member of the ‘video’ group. User volumio already is a member of ‘video’, so not sure what the problem is.

11

Thank you both for your answers!!!
I stoped trying after some unsuccessful attempts…

As chisms1 says there is a message from raspi check after the failure of getting access … I will post a screenshot here later!!

Thnx again!!

12

If you run vcgencmd from Volumio’s command line without sudo, you’ll receive an error message

VCHI initialization failed

The culprit ist /dev/vchiq. In standard Raspbian (Stretch), it looks like this:

$ ls -l /dev/vchiq crw-rw---- 1 root video 246, 0 Jun 16 23:28 /dev/vchiq
however in Volumio it is instead

crw------- 1 root root 246, 0 Jun 17 22:13 /dev/vchiq

I order to enable vcgencmd for the volumio user you therefore have to modify the group and the access mode of /dev/vchiq:

sudo chmod g+rw /dev/vchiq sudo chgrp video /dev/vchiq
After that, vcgencmd works without sudo. Check if this makes RasPi Check work for you.

Two things to note, though:

  • I don’t know if this modification will survive a Volumio version update.
  • You have to decide for yourself whether being able to use RasPi Check is worth the risk of having ssh enabled all the time. As you cannot change the volumio user’s password without breaking at least some of Volumio’s functionality (e.g. plugin installation), you’ll have a door permanently open if you do so. Otherwise, just turn on ssh if you need it, and turn it off afterwards.

Regards,
Victor

13

Thank you very much for your reply!!!
I will consider the risk and may be I’ll try it!
I did not know that enabling ssh will create problems potentially!!

Thanx again!
All the best
Michael

14

SSH by itself does not necessarily create a security risk, but having a well-known standard user (volumio) with a non-changeable, well-known default password does.

It would actually be much better to

  • disable ssh access for the volumio user
  • create a dedicated user for ssh access using your own password

However I’m not sure if taking SSH access away from the volumio user will cause problems, so I haven’t tried yet. If I do, I’ll report here…

Cheers,
Victor

15

Create a dedicated user for SSH access

If have gone about creating a dedicated user account for ssh access so we can get rid of the barn door opened by the volumio user and his unchangeable default password. As ssh is disabled by default, we should not risk any problems when taking it away from the volumio user. So the process is pretty straightforward. We’ re going to create a user with the same privileges as the volumio user, and then disable ssh login for user volumio:

1: Create an new user (e.g. myuser)

sudo adduser myuser

You will be asked to enter a new password. This is where you can set a strong, secure password of your own! You can ignore the rest of the questions asking for finger data (but you can of course supply meaningful answers if you wish!).

  1. Assign all groups the volumio user belongs to. In addition, add your user to the group sudo so he/she can perform privileged operations:

sudo usermod -a -G volumio,adm,dialout,cdrom,floppy,audio,dip,video,plugdev,netdev,input,i2c,spi,gpio myuser sudo usermod -a -G sudo myuser

  1. At this point, it is time to test if everything works. Open a second connection to your Volumio system, but this time, log in with the new user. When logged in, type
sudo ls

to test if sudo works, too. If all is fine and you don’t get any error messages, you’re good to go for the last step:

  1. Restrict ssh access to your newly created user. This takes ssh access away from all users except those explicitly listed:
sudo vi /etc/ssh/sshd_config

Go to the bottom of the file and add the line

AllowUsers myuser

Attention: make sure not to mistype your user name here, or you will effectively have locked you out of your system, at least ssh-wise (aka as shooting oneself in the foot)! Save, exit and reboot - done! If now you try to log in as user volumio, you will receive an error message ‘Permission denied’. So now you can leave ssh enabled all the time without fear of unauthorized intruders.

Notes:

  • Resetting Volumio to factory defaults will restore the default password for the volumio user and disable ssh. I don’t know if it also restores the sshd_config file, so I wouldn’t rely on it.
  • These instructions have been tested and found to work with Volumio 2.411. For other versions, at least check what groups the volumio user belongs to (type groups volumio) and adjust the usermod command in step 2 if necessary.
  • You can always revert the changes by removing the line containing AllowUsers from /etc/ssh/sshd_config if you so desire.
  • Do not be tempted to enable root ssh access in /etc/ssh/sshd_config. It is disabled by default for a good reason: security.

Cheers,
Victor

16

I have found a problem with the modification I suggested for enabling vcgencmd: The permissions for /dev/vchiq are reset by a reboot!

In order to make the changes permanent, we have to reapply them at boot time by adding the necessary commands in /etc/rc.local. Type

sudo nano /etc/rc.local
Navigate to the line above exit 0 and insert these lines:

# make /dev/vchiq accessible for the video group chgrp video /dev/vchiq chmod g+rw /dev/vchiq Save and exit. From now on, /dev/vchiq will be accessible even after rebooting.

Cheers,
Victor