How to make the machine available for several remote users?
Other users may either have separate accounts on the VM or share one account. The new account must be created using appropriate system command, e.g.
$ sudo useradd -m new_user_name
The new user must also have his ssh key defined:
$ sudo su new_user name $ cd $ mkdir .ssh $ cat - >.ssh/authorized_keys
(paste user’s public key to the terminal) <Ctrl-D>
$ chmod 600 .ssh/authorized_keys
If you want to allow two remote users to access a single account (or you are using several keys, e.g. from home and from office), just append the additional key at the end of .ssh/authorized_keys file, e.g.
$ cat - >>.ssh/authorized_keys
(paste additional key to the terminal) <Ctrl-D>
Caution: it is easily possible to cut the branch you are sitting on: spoil the authorized_keys file so that you cannot log in anymore. It's better not to play with the only system account!