Ubuntu 17.04: manually generate guest account

Somehow, my 'guest' account disappeared from my machine. I found this account very useful, so I tried to setup a 'guest' on my own. However, I cannot find any option in the Users and Groups dialogue that support the concept of delete all generated files upon exit.

What is the best way to achieve this? There is no setting in the lightdm configuration files that says 'no-guest'.

Solution 1:

According to this article on OMG Ubuntu and this bug report on Launchpad, Ubuntu has disabled the guest sessions on 16.10 and 17.04 because of a security issue. The guest session is not properly confined and someone with physical access could gain elevated privileges.

If you are aware of the security issue and want to enable the guest account anyway, accepting the possible threat, there is an official procedure to do so:

How? By editing /etc/lightdm/lightdm.conf and entering the following:

# Manually enable guest sessions despite them not being confined
# IMPORTANT: Makes the system vulnerable to CVE-2017-8900
# https://bugs.launchpad.net/bugs/1663157
[Seat:*]
allow-guest=true