Synology DSM - Can't log as root (but works with admin)

If your synology is in DSM6 and you're logged with a user part of administrator group, you can do :

sudo -i

enter your root/admin password

or even sudo su - (it works to)

now you're root tadaaa

Your Synology probably upgraded to DSM6, in which security has been hardened... In DSM6 you can no longer use root for SSH, but you can use any other member account of the administrators group. Mind that you now need to sudo when logged in using SSH.

See the DSM6 release notes!

In DSM Version 6 you can still login as root when using RSA keys. Therefore just copy your public key as admin to your Synolgy:

$ cat ~/.ssh/id_rsa.pub | ssh [email protected] 'umask 077; cat >>/tmp/authorized_keys'

After that login to your Synology as admin and become root:

$ ssh [email protected]
[email protected]'s password:
admin@My-Synology:/$ sudo -i
Password: 

No create the .ssh directory for root, move your key and change the owner of that file:

root@My-Synology:~# mkdir -m0700 /root/.ssh
root@My-Synology:~# mv /tmp/authorized_keys /root/.ssh/
root@My-Synology:~# chown root:root /root/.ssh/authorized_keys

After that you can login to your Synology as root without having to enter the password.