Add Guest user to Persistent flash drive

Question

Persistent flash drives made using the leading boot drive creators such as mkusb, Unetbootin, Rufus, YUMI, etc do not come with a Guest user, as does a normal desktop install or Full install to pendrive.

It is possible to log into a flash drive using Try Ubuntu, which will also permit a temporary session, however there is too much privilege with a try Ubuntu session, such as being able to format the internal drives.

I would like to add a Guest user that is exactly the same as the Guest user in a Full install, No power to do anything destructive and a full cleansing of the Guest account after every use.

@Gunnar Hjalmarsson: Ubuntu 16.04.3, Persistent install per mkusb. — C.S.Cameron, Aug 16 '17 at 23:55
Maybe you can configure LightDM to autologin to the guest session. — Gunnar Hjalmarsson, Aug 17 '17 at 00:01
@Gunnar Hjalmarsson: I think lightdm is part of a read only file system on a persistent drive, iso9660 with mkusb and filesystem.squashfs with syslinux installers. maybe there is a way to add lightdm to casper-rw ? There is a usr/share there. — C.S.Cameron, Aug 17 '17 at 01:11
@Gunnar Hjalmarsson: I opened casper-rw/upper/etc/lightdm/lightdm.conf and changed allow-guest=true and now there is a guest, please submit as an answer. — C.S.Cameron, Aug 17 '17 at 01:46
Great! While I just gave a hint, you are the one who solved the problem, so I think you should submit your solution as an answer. It's perfectly fine at Ask Ubuntu to answer your own question. — Gunnar Hjalmarsson, Aug 17 '17 at 04:29

C.S.Cameron · Accepted Answer · 2017-08-18T17:09:35.963

Guest User accounts are controlled by lightdm.conf.

For a grub2 booters with persistent casper-rw partitions, such as mkusb:

Open casper-rw/upper/etc/lightdm/lightdm.conf and change "allow-guest=true". Now there will be a Guest account.

For Syslinux booters with persistent casper-rw files such as UNetbootin: First mount the casper-rw file:

sudo mkdir /media/casper

sudo mount -o loop casper-rw /media/casper/

Then edit casper/upper/etc/lightdm/lightdm.conf and change "allow-guest=true". A guest account will be added to boot options.

CAUTION A bug has been issued for Guest session 16.10 and newer: Bug. It concerns not confined processes.

For 17.04 Gnome, LightDM has been replaced by GDM and GDM does not include a Guest session.

The user can install LightDM in 17.04 Gnome using sudo apt install lightdm The install process will ask to remove GDM.

17.04 Gnome reports as being unconfined when in a guest session, caution applies.

Thanks to Gunnar Hjalmarsson for the hint and mc4man for the bug warning.

Add Guest user to Persistent flash drive

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