Unable to SU to Root on Ubuntu Server 18.04LTS

[mhumm2]

Strange. I can sudo all day, but when I su root and enter my password, I get back: su: Authentication failure

What am I doing wrong and how can I fix it? I would like to su so I can setup OpenVPN on my server and my Kubuntu 14.04LTS computer as a client.

[jlittle]

Er... I'd expect that su or su root would ask for root's password, which is not normally set in Ubuntu.

Can you use sudo -i?

[nlsthzn]

My go to (which may be the wrong way) -

sudo su

[mhumm2]

Yep, sudo su worked. Thank you.

[kubicle]

My go to (which may be the wrong way) -

sudo su

It's not "wrong" per se, but "sudo -i" is technically better (see here for a short description: https://help.ubuntu.com/community/Ro...udo_and_shells)

Alternatively, one could use "sudo su -" or "sudo su -l" to get a login shell, but "sudo -i" avoids unnecessary chaining.

[oshunluvr]

The answer to the original question is - because Ubuntu and flavors do not install with a root password. "su" requires that the user you're attempting to switch to has a password. "sudo" uses YOUR password to elevate you to root privilege.

Ubuntu's don't have a root password because it's considered unnecessary and unsafe.

However, it's your install so you can make it as unsafe as you like. "sudo passwd root" will create a root password and then you can (unsafely) log in as root.

[mhumm2]

Excellent explaination oshunluvr. Thank you.