The $400 World Wide Mobile Me . . . Part 4: Frequently Asked Questions (FAQ)

∏This is Part 4 of a 4 Part Article.
Part 1 covers assembling the hardware

Part 2 covers provisioning the Raspberry Pi with Software

Part 3 covers Final Configuration of the hotspot

Part4 is Frequently Asked Questions

While I can’t be there to troubleshoot all your questions and problems as a community we can learn from each other.

Note: I am not going to be the general help desk for the Raspberry Pi, Raspian, or anything not directly connected to this article.  Try a Google or other search engine  to find your problem or error message, or go to stack exchange and ask them.   I reserve the right to ignore any questions that in my Opinion do not apply directly to this series how to!  Do not expect an email or call.   

If you have a problem, or a question in assembling this particular HOTSPOT send an email to:

K0BSB@arrl.net

 

 Frequently Asked Questions:

Q: I try using Pi Finder “Terminal” button, the screen opens up, and tells me that it can’t connect.  (Example: you get a message like, “Error: All configured authentication methods failed “)  What am I doing wrong?

A: You are having an SSH Access problem.  Check the following points:

  • Check your Pi Finder screen and make sure the SSH User ID is pi-star and the SSH Password is Raspberry  Note you should change it to something else, as someone can easily get in and use your system for nefarious purposes.
    • The easiest way to change the pi-star password is to wait until everything is done, and at the bottom of the configuration page you can change the password simply.
    •  If you want to change the password from the Raspberry Pi console enter the following commands:
      • sudo passwd pi-star
      • if this is the first time you have entered sudo you may be asked to enter the original password most likely raspberry
      • it will ask you to enter in the new password
      • it will ask you to re-enter the new password
      • if everything checks out it will inform you the password has been changed
      • do not forget to update the Pi-Finder screen with the new password!
  • The IP Address was used before with a different MAC Address or ID.  This can happen if you write new software onto the µSD Card.  On your computer (Not the Raspberry Pi) edit the file .ssh/known_hosts, find the previous IP address of the pi-star system and delete the line and save the file.  
    • On a MacOS or Linux System Open a terminal session and enter:
      • sudo nano ~/.ssh/known_hosts
      • scroll down to the pi-star previous IP address and delete the line
      • save the file
    • try accessing the Raspberry Pi with the Pi Finder Terminal button to see if it works now.
  • You skipped a step in the SD Card preparation.  SSH is disabled.  Starting in October 2016 the Raspberry Pi Foundation with the release of the new Pixel desktop shut off SSH.   They explain what they have done, and how to fix it here. Its a good lesson in Raspberry Pi Security.  To Summarize:
    • Power off the Raspberry Pi
    • Remove the µSD Card, and put it back in a card reader on your Laptop/Desktop
    • Open the drive volume:  boot
    • create a blank file called ssh in the /boot directory (i.e. /boot/ssh)
    • Note: there is no extension, if your editor created a file extension rename the file without one.
    • eject the drive
    • place the µSD Card back in the Raspberry Pi and boot it up.
    • SSH should now work

Q: I keep forgetting to type sudo before all the commands.  Isn’t there a simpler way?

A:  Yes, but it is a bit dangerous.  You could put the terminal session into administrator mode.  Understand that in UNIX like systems Administrative or root mode has very little protections and you can seriously damage you system.  For example, if you tell the system to delete a file(s) it will do so without question, including its own operating system essential files.  In other words, if you don’t watch what you are doing in this mode very carefully, you can brick the system.   If you want to easily enter root mode on the pi, simply type:

  • sudo bash

To exit root mode enter:

  • exit

another way is to enter:

  • su –

but that will require the root password.

Note: It’s probably a good thing to set the root password on the Raspberry Pi.  It is not set initially and most people never set it.  There are security considerations for this. If, however, you need to recover the disk drive during the boot sequence a program called fsck (the Linux version of ScanDisk) will ask for it.  If you have not set a root password, you will not be able to proceed further and the only alternative is to re-write the µSD card with the last backup.  Essentially you have a brick on your hands.  For this reason I always set the root password and to something very secure.  Please note that the error I have just described would not be visible as we have configured the DHAP as a headless system.  To detect this error, you would need a monitor with HDMI input and a USB keyboard connected to the DHAP.  I have such a setup at home, I just don’t take it traveling with me.  The Raspberry Pi being so  small and simple tends to make people thing it is not complex.  Hook a HDMI monitor to the Raspberry Pi and watch the boot sequence, it is pretty complex, all the programs running in the background.  But I digress…

To set the root password enter:

  • sudo bash
  • passwd root
  • set the password
  • exit
  • you should return to a pi-star prompt

 

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

This concludes the 4 Part Series The $400 World Wide Mobile Me….

73,

Happy communicationg, and having fun with your new Hotspot!

de

Barry, K0BSB

Leave a Reply

Your email address will not be published. Required fields are marked *

fifteen − nine =