Setting up a new user

This page shows how to create non-privileged user accounts. i.e. those used for daily work, including desktop use and remote logins, and how to grant admin access to such accounts if needed.

Overview

Creating user accounts provides users with their own $HOME directory and allows you (the root user) to limit the access those user accounts have to the operating system configuration files.

Using them increases security, because they limit possible actions and thus possible damage (even from accidental errors).

Warning: If you are using a "diskless" or "data" disk mode installation, refer to the section Persistent Home directory before proceeding further.

Creating a new user

The root account should be used only for local administrative purposes that require elevated access permissions. Regular or non-privileged user accounts can be created in two ways:

setup-user

The setup-user script allows quick and simple setup of user accounts. To Create a regular user account using the above script:

# setup-user

User will be prompted for options. This script uses adduser in the backend.

adduser

# adduser [-g "<Full Name>"] <username>

By default, adduser will:

• prompt you to set a password for the new user
• create a home directory in /home/<username>
• set the shell to the one used by the root account (ash by default)
• assign user ID and group ID starting at 1000
• set the GECOS (full name) field to "Linux User,,,"

Tip: The optional -g "<Full Name>" above sets the GECOS field.

This can be very useful to specify. Setting this string - at least equal to the username - makes the user distinguishable, e.g. when they are listed at the login screen of a display manager.

Usage (from "man busybox"):

adduser [OPTIONS] USER [GROUP]

Create new user, or add USER to GROUP

     -h --home DIR           Home directory
     -g --gecos GECOS        GECOS field
     -s --shell SHELL        Login shell named SHELL by example /bin/bash
     -G --ingroup GRP        Group (by name)
     -S --system             Create a system user
     -D --disabled-password  Don't assign a password, so cannot login
     -H --no-create-home     Don't create home directory
     -u --uid UID            User id
     -k SKEL                 Skeleton directory (/etc/skel)

The new user gets listed in

Contents of /etc/passwd

root:x:0:0:root:/root:/bin/ash . <username>:x:1000:1000:<username>:/home/<username>:/bin/ash

Now you should be able to issue the command exit and login to the newly created account. Refer #adduser for detailed detailed syntax.

Group management

Note: If you used setup-desktop to install your desktop environment, you will be able to use your desktop without issues, as elogind is up and running automatically for you.

If you installed your desktop manually by adding individual packges, and if seatd is used, then users that want a graphical environment need to be added to the video and seat groups:

# adduser '<username>' video
# adduser '<username>' seat

Refer #15409 regarding the security concerns.

To add your user to a group you can also use the following command:

Usage (from "man busybox"):

addgroup [-g GID] [-S] [USER] GROUP

Create a group or add a user to a group

    -g --gid GID    Group id
    -S --system     Create a system group

To see what group(s) a <username> is in, use the following command:

# id <username>

Note: You need to log out for the group change(s) to take effect.

Admin user Management

If a user really must be allowed to have access to the root account, the <username> must be added to the wheel group. Also ensure that either doas or sudo is available.

wheel group

The setup-user script also allows quick and simple setup of admin user accounts. To Create a new user as admin user, using the above script:

# setup-user -a <username>

The above command will create an admin user, by adding the user to wheel group and installs doas, if not already installed.

To add an existing user as admin user:

# adduser <username> wheel

Remember to install doas, if not already installed.

doas

The doas command provides a way to perform commands as another user. It aims to be a simplified and lightweight replacement for sudo.

# apk add doas

You will want to allow members of the wheel group to use root privileges with doas. To do this, open the doas config file:

# <editor> /etc/doas.d/doas.conf

Add the following line and save the file:

permit persist :wheel

Warning: It's recommended to not run complete applications, like editors, as root just to modify administrative files.

• doasedit or sudoedit(being deprecated in favour of doas) enables starting an editor with a temporary copy of a file, which overwrites the original file after the user modifies and saves it. For example, sudoedit /etc/apk/lbu.conf
• Many desktop environments and file browsers support using admin:/// in their address bars, to access files through a local gvfs-admin mount.

sudo

Sudo (su “do”) allows a system administrator to delegate authority to give certain users (or groups of users) the ability to run some (or all) commands as root or another user while providing an audit trail of the commands and their arguments.

The sudo package is an alternative to using the BSD-like doas, but is a much larger package.

It may be used as follows: adding a custom user configuration file to avoid having to deal with manually changing configuration files later during package upgrades.

apk add sudo
NEWUSER='yourUserName'
adduser -g "${NEWUSER}" $NEWUSER
echo "$NEWUSER ALL=(ALL) ALL" > /etc/sudoers.d/$NEWUSER && chmod 0440 /etc/sudoers.d/$NEWUSER

Home directory permissions

`adduser` creates home directories with permissions `rwxr-sr-x`. This makes the directory readable by all other users on the system. If you prefer to not allow other users to read your home directory, the permissions can be changed:

chmod o-rx <path-to-directory>

Tip: Multi-user collaboration

If --ingroup isn't set, (default) the new user is assigned a new GID that matches the UID. If the GID corresponding to a provided UID already exists, adduser will fail.

This ensures new users default to having a "user's private group" (UPG) as primary group. These allow the system to use a permission umask (002), which creates new files automatically as group-writable, but only by the user's private group. In special set-group-id (collaboration) directories, new files can be automatically created writable by the directory's group.

Persistent Home directory

If using a "diskless" or "data" disk mode installation, it's important to make the /home directory persistent

• Either the /home filesystem needs to be mounted from a writable partition, or
• the /home directories have to be added to the lbu backup, and a new local backup needs to be committed after creating the user:

# lbu include /home # lbu commit

(Not recommended, as reverting to an older .apkovl will also revert the files in /home).

Common permission groups

This material is work-in-progress ... Need to note a few security implications outlined on debian/wiki SystemGroups (Last edited by Prabuanand on 13 Aug 2024.)

Groups are needed for certain operations on your system.

(Names taken from https://git.alpinelinux.org/alpine-baselayout/tree/group)

adm Used for system monitoring tasks. disk Raw access to disks. Mostly equivalent to root access. lp Members of this group can enable and use printers. wheel Administrator group, members can use doas to run commands as root if enabled in the doas configuration. floppy Access to floppy drives and other removable (non-optical) drives (like USB flash drives). audio Direct access to sound hardware (the soundcard or a microphone). cdrom For access to disk writers and mounting DVD, BR or CD-ROM disk as normal user. dialout Full and direct access to serial ports. input Access to input devices. tape Needed to give a set of users access to a tape drive. video Access to video capture devices (like a webcam). netdev For network connections management as normal user. kvm Needed to use the KVM acceleration of virtual machines. games Access to some game software. cdrw Needed to write RW-DVD, RW-BR or RW-CD disk on a disk writing device. usb Needed to access special USB devices, deprecated group. users Needed if you plan to used common files for all users, mandatory as desktop usage.

Old newbie notes

User creation and defaults

The following commands will set up root environment login, then assign a new password:

cat > /root/.cshrc << EOF
unsetenv DISPLAY || true
HISTCONTROL=ignoreboth
EOF

cp /root/.cshrc /root/.profile

echo "secret_new_root_password" | chpasswd

By default, remote management cannot be done directly with the root account. Because of SSH security we need to set up a remote connection account that will be used to switch to the root user via the su command, once connected.

Here's an example: create user named "remote" and a user named "general". We will set up a hardened, limited, user environment and create those two users:

mkdir -p /etc/skel/

cat > /etc/skel/.logout << EOF
history -c
/bin/rm -f /opt/remote/.mysql_history
/bin/rm -f /opt/remote/.history
/bin/rm -f /opt/remote/.bash_history
EOF

cat > /etc/skel/.cshrc << EOF
set autologout = 30
set prompt = "$ "
set history = 0
set ignoreeof
EOF

cp /etc/skel/.cshrc /etc/skel/.profile

adduser -D --home /opt/remote --shell /bin/ash remote

echo "secret_new_remote_user_password" | chpasswd

adduser -D --shell /bin/bash general

echo "secret_new_general_user_password" | chpasswd

Tip: "general" is the name of the user. That name MUST contain ONLY lowercase letters, NO spaces and NO symbols

To add newly created users to groups that may come in handy for desktop usage, you run this command as root:

for u in $(ls /home); do for g in disk lp input audio cdrom dialout video netdev games users; do addgroup $u $g; done;done

See also

• Users and groups - Archwiki