SSH Service Account

By default the linux “fmadio” account is the default user account and can not be removed. Additional SSH user accounts can be added to the system, below are the specific steps.

Step 1) Create the account

Create the account using the usual linux command adduser  In the below examples the account is named “service” this can be changed freely.

Run the command to create the account

sudo adduser service -G staff

Example output

fmadio@fmadio200v4-636:~$ sudo adduser service -G staff
Changing password for service
New password:
Bad password: too short
Retype password:
passwd: password for service changed by root
fmadio@fmadio200v4-636:~$

Step 2) Create .ssh directory (optional)

To create an SSH Key based login

Change to be the service user

sudo su service

Then create the .ssh directory

cd
mkdir .ssh

Typically create an authorized_key file for password / key based login

vi .ssh/authorized_keys

Then paste in the public access keys

Full command shown below

service@fmadio200v4-636:/home/fmadio$ cd
service@fmadio200v4-636:~$ mkdir .ssh
service@fmadio200v4-636:~$ pwd
/home/service

The usual Linux / Bash shell configuration can be done here

Step 3) Enable sudo

Edit the sudoers files to allow the service account run sudo

sudo vi /etc/sudoers

Then add the new user account, example shown below for service

service@fmadio200v4-636:~$ sudo cat /etc/sudoers
#
# This file MUST be edited with the 'visudo' command as root.
#
# See the man page for details on how to write a sudoers file.
#

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root    ALL=(ALL) ALL
fmadio  ALL=NOPASSWD: ALL
service ALL=NOPASSWD: ALL
service@fmadio200v4-636:~$

Step 4) Copy system files for persistence

The system files need to be persisted, otherwise the service account will not be preserved

Copy the home directory

sudo mkdir /mnt/store0/home/
sudo cp -Rp /home/service /mnt/store0/home/

Copy the system files

sudo cp /etc/passwd /opt/fmadio/etc/
sudo cp /etc/sudoers /opt/fmadio/etc/

Step 5) Update boot.lua

For firmware prior to Version XXXXX the following needs to be added to the boot.lua file. Firmware from Version XXXX does this automatically and this is not required.

Edit the file

/opt/fmadio/etc/boot.lua

Append these lines at the end of the file

-- service account
os.execute([[cp -Rp /mnt/store0/home/* /home/]])
os.execute([[cp /opt/fmadio/etc/passwd /etc/]])
os.execute([[cp /opt/fmadio/etc/sudoers /etc/]])

Step 6) Reboot

After reboot, confirm login using the service account works correctly.