A piggy bank of commands, fixes, succinct reviews, some mini articles and technical opinions from a (mostly) Perl developer.
For username "foo":
$ adduser foo
$ passwd foo
$ sudo usermod -aG sudo foo
$ mkdir -p /home/foo/.ssh
$ cat the_public_key.pem >> /home/foo/.ssh/authorized_keys
$ chown -R foo:foo /home/foo/.ssh
$ chmod 700 /home/foo/.ssh
$ chmod 600 /home/foo/.ssh/authorized_keysDisable default account:$ usermod -s /usr/sbin/nologin default_username
Notes:- Not useradd.
- Even when logging in with just SSH key, user must have a password. It will only be used for sudo commands.
Define text editor
$ sudo update-alternatives --config editor
Edit /etc/sudoers file
$ sudo visudo /etc/sudoers
Add a user to sudo group
$ sudo usermod -aG sudo username
or
$ sudo gpasswd -a username sudo
(but CentOS uses "wheel" group instead)
Default config for Ubuntu 22:
# User privilege specification
root ALL=(ALL:ALL) ALL
# Members of the admin group may gain root privileges
%admin ALL=(ALL) ALL
# Allow members of group sudo to execute any command
%sudo ALL=(ALL:ALL) ALL
Remove login for default users:
$ usermod -s /usr/sbin/nologin username
Sources:
Posts
