Outline

This is a step-by-step guide to allowing a non-admin user to have SSH access to a Synology NAS. Synology - and many others - think this is a security risk and you should not do it. Fair enough. You can make that decision yourself.

But if you do want to do it, here are the steps that worked for me. They were a hack between [this] blog post and the output from ChatGPT, both of which had partial errors or missing bits.

This was done on a Synology DS423+ on DSM 7.2.2-72806 Update 3.

Steps

This example has a user - called test_user - that you want to give SSH access to. And that you have enabled SSH access on the Synology NAS so you - as an admin user, can SSH into it.

To Enable SSH, you can do Control Panel -> Terminal and SNMP -> tick Enable SSH service.

First SSH into the NAS. You can then enter root access by using sudo -i and re-entering your password.


# firstly login to the server using the command
ssh user@ipaddress -p XX

# get root access
sudo -i

Next, we need to edit /etc/passwd. To do this we used vi. I hate vi. Key things for using vi are:

i to enter insert mode where you edit things.
Esc to exit insert mode.
:wq to save the changes and quit.
:q! to quit without saving changes. I used this as save changes for about twenty minutes.

When you go into insert mode, find the user you want to give SSH access to, and change /sbin/nologin to /bin/sh.


# edit the file
vi /etc/passwd
# i to enter insert mode
# :wq to save and exit

Once you have done this copy the file $HOME/.profile to /var/services/homes/test_user and edit it again. This time,change the value of $HOME to /var/services/homes/test_user.


# copy the file
cp $HOME/.profile /var/services/homes/test_user

# edit the file
vi /var/services/homes/test_user/.profile
# i to enter insert mode
# :wq to save and exit

You can now exit root access by typing exit. And exit the SSH session by typing exit again.

Voila, that user should now have SSH access to the Synology NAS.