Can't su root after editing PAM confiugration on Rackspace Linux box I've just hosed a system. Working on pam-ldap on an Ubuntu box, I've run `pam-auth-update` and told it to override local modifications (which had previously allowed for `sudo su`, but I was having issues with `sudo <arbitrary command>`. After applying the settings I can no longer `su root`. Now I'm pretty much locked out of the box and since it's on the cloud the concept of 'boot access is root access' doesn't really apply. Any ideas how I can rescue the box?

Looks like Rackspace has something called Rescue Mode comparable to the 'root access is boot access' on their cloud. You can boot another instance and mount the disk from the damaged machine just as you would have in the old fashioned days with a LiveCD.