Setting up a new user: Difference between revisions

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The ''root'' account should only be used for administrative purposes that require its elevated access permissions.
The <code>root</code> account should be used only for local administrative purposes that require elevated access permissions.


This page shows the creation of separate user accounts, e.g. for remote connections or desktop usage.
This page shows how to create non-privileged user accounts. i.e. those used for daily work, including desktop use and remote logins.


= Overview =
= Overview =


Creating user accounts provides the users their own $HOME directory and allows you (the root administrator) to limit the access that these user accounts have to the operating system's configuration.
Creating user accounts provides users with their own {{path|$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 the security, because they limit possible actions and thus the possible damage (even from accidental errors).
Using them increases security, because they limit possible actions and thus possible damage (even from accidental errors).


== Creating a new user ==
= Creating a new user =


A new user is created with:


{{Cmd|adduser <username>}}
{{Warning|If using a '''"diskless" or "data" disk mode''' installation, it's important to make the <code>/home</code> directory persistent.
<br>
* Either the <code>/home</code> 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:
{{Cmd| # lbu include /home
# lbu commit
}} (Not recommended, as reverting to an older .apkovl will also revert the files in /home).
}}


By default, it will:
Regular user accounts can be created with:
* prompt to set a password for the new user.
{{Cmd|# adduser [-g "<Full Name>"] <username>}}
 
By default, <code>adduser</code> will:
* prompt you to set a password for the new user
* create a home directory in {{Path|/home/<username>}}
* create a home directory in {{Path|/home/<username>}}
* set the shell set to the one used by the ''root'' account (ash by default)
* set the shell to the one used by the <code>root</code> account (ash by default)
* assign user ID and group ID at 1000+
* assign user ID and group ID starting at 1000
* set GECOS field to ''Linux User,,,''.
* set the GECOS (full name) field to "Linux User,,,"


For example, if we create a new user with name "test":
{{Tip|The optional <code>-g "<Full Name>"</code> 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.
}}


  # adduser test
'''If a user ''really must'' be allowed to have access to the root account''', the <username> can be added to the '''wheel''' group and <code>{{Pkg|doas}}</code> ("do as") may be installed:
  Changing password for test
  # adduser -g "<username>" <username>
  New password:
  # adduser <username> wheel
Retype password:
  # apk add doas
passwd: password for test changed by root


The new user can be seen in  
You will want to allow members of the '''wheel''' group to use root privileges with <code>doas</code>. To do this, open the <code>doas</code> config file:
 
{{Cmd|# <editor> /etc/doas.d/doas.conf}}
 
Add the following line and save the file:
{{Cmd|permit persist :wheel}}
 
{{Warning|It's recommended to '''not''' run complete applications, like editors, as root just to modify administrative files.
<br>
* [https://github.com/AN3223/scripts/blob/master/doasedit <code>doasedit</code>] or <code>sudoedit</code>([https://wiki.alpinelinux.org/wiki/Release_Notes_for_Alpine_3.15.0#Move_from_sudo_to_doas being deprecated in favour of <code>doas</code>]) 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, <code>sudoedit /etc/apk/lbu.conf</code>
* Many desktop environments and file browsers support using <code>admin:///</code> in their address bars, to access files through a local gvfs-admin mount.
}}
The <code>sudo</code> package is an alternative to using the BSD-like <code>doas</code>, 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
 
<br>
 
If no seat manager like [[elogind]] or [[seatd]] is being used and running, then users that want a graphical environment need the '''video''' and '''input''' groups:
# adduser '<username>' video
# adduser '<username>' input
 
The above is highly discouraged. See {{Issue|15409}}.
 
The new user gets listed in  


{{Cat|/etc/passwd|root:x:0:0:root:/root:/bin/ash
{{Cat|/etc/passwd|root:x:0:0:root:/root:/bin/ash
Line 37: Line 74:
.
.
.
.
test:x:1000:1000:Linux User,,,:/home/test:/bin/ash}}
<username>:x:1000:1000:<username>:/home/<username>:/bin/ash}}
 
So, now it's possible to ''exit'' and login to the new account.


Now you should be able to issue the command <code>exit</code> and login to the new account.


= Options =


=== adduser ===
=== adduser ===


Usage:
Usage (from "man busybox"):


<pre><nowiki>adduser [OPTIONS] USER [GROUP]</nowiki></pre>
<pre><nowiki>adduser [OPTIONS] USER [GROUP]


Create new user, or add USER to GROUP
Create new user, or add USER to GROUP


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


Those options only work for newer versions:
{{Tip|Multi-user collaboration
If <nowiki>--ingroup</nowiki> 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.


*  -k SKEL Skeleton directory (/etc/skel)
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.
}}


An important multi-user collaboration thing to note:
=== addgroup ===


If <nowiki>--ingroup</nowiki> isn't set (default) the new user is assigned a new GID that matches the UID. And if the GID corresponding to a provided UID already exists, adduser will fail.
Usage (from "man busybox"):


This ensures new users default to having a "user's private group" (UPG) as primary group. They allow using a permissive umask (002), with which new files are automatically created group-writable to just the user's private group. And which allows that in special set-group-id group (collaboration) directories, new files can automatically become writable to the directory's group.
<pre><nowiki>addgroup [-g GID] [-S] [USER] GROUP


=== addgroup ===
Create a group or add a user to a group
 
    -g --gid GID    Group id
    -S --system    Create a system group
</nowiki></pre>
 
= 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:
 
{{Cmd| chmod o-rx <path-to-directory>}} 
 
= Legacy =


Usage:
=== Common permission groups ===


<pre><nowiki>addgroup [-g GID] [-S] [USER] GROUP</nowiki></pre>
{{Draft|Need to note a few security implications outlined on [https://wiki.debian.org/SystemGroups debian/wiki SystemGroups]}}


Add a group or add a user to a group
Groups are needed for certain operations on your system.


* --gid GID  Group id
(Names taken from https://git.alpinelinux.org/alpine-baselayout/tree/group)
*  --system  Create a system group


Where the most common Alpine base groups permissions are:
{{Cmd|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) dirves (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.}}


* '''disk''':x:6:root,adm  Only if need usage vith virtual machines and access to other partitions over new disks for
To add your user to a group use the following command:
* '''lp''':x:7:lp  IF will need to use printing services and printers management
{{Cmd|# adduser <username> <group>}}
* '''wheel''':x:10:root  Administrators group, members can use <code>sudo</code> to run commands as root if enabled in sudo configuration.
{{Note|You need to log out for the group change(s) to take effect.}}
* '''floppy''':x:11:root  Backguard compatible group, use only if need access to external special devices
* '''audio''':x:18:  Need for audio listening and management of sound volumes as normal user
* '''cdrom''':x:19:  For access to disck writers and mounting DVD, BR or CD rom disk as normal user
* '''dialout''':x:20:root  Need for dial private connections and use of modems as normal users
* '''tape''':x:26:root  Need have into this if plan to use special devices for backup.. rarelly in no servers
* '''video''':x:27:root  For usage of cameras, mor thant one GPU special features, as normal user
* '''netdev''':x:28:  For network connections management as normal user
* '''kvm''':x:34:kvm Only if as normal user will manage graphically virtual machines.. rarelly on no servers
* '''games''':x:35:  Need if you want to play games also specially need if will share score between users
* '''cdrw''':x:80:  To write RW-DVD, RW-BR or RW-CD disk on a disk writing device
* '''apache''':x:81: Need if you will perfom development as normal user and want to publish locally on web server
* '''usb''':x:85: Need to access to special usb devices, deprecated group
* '''users''':x:100:games If you plan to used common files for all users, mandatory as desktop usage


A more complete list are in : https://git.alpinelinux.org/alpine-baselayout/tree/group more detailed user and group management are in the sections below:
To see what group(s) a <username> is in, use the following command:
{{Cmd|# id <username>}}


= Old newbie notes =


== Users creation and defaults ==
=== User creation and defaults ===


'''Only ''root'' can manage users'''. Creating an account allows it to have it's own <code><nowiki>$HOME</nowiki></code> directory and allows you to limit access to the configuration of the operating system for security reasons. So the following commands will first setup root environment login and then assing a new password:
The following commands will set up root environment login, then assign a new password:


<pre><nowiki>
<pre><nowiki>
Line 118: Line 175:
</nowiki></pre>
</nowiki></pre>


The remote management cannot be done with root directly by default, due ssh security, so we need to setup an remote connection account to made "su" once connected.  
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.


The most recommended it's having a access user here named "remote" and normal general usage user here named "general" for convenience, in the next commands we will setup a very hardened limited environment for any new user and created those two users:
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:


<pre><nowiki>
<pre><nowiki>
Line 150: Line 207:
</nowiki></pre>
</nowiki></pre>


{{Tip|"'''general'''" are the name of the user, that name MUST be only lowercase letters and no spaces with no symbols}}
{{Tip|"'''general'''" is the name of the user. That name MUST contain ONLY lowercase letters, NO spaces and NO symbols}}


Note that those users are created with minimal settings.
Note that those users are created with minimal privilege settings.


== Users management and system access ==
== User management and system access ==
 
But this user will not have enough privileges for a desktop made purposes, Alpine comes with high security so administrator (the ''root'' account owner) must perform the management of that user. Take care, for a server made there's no similar procedure!
 
Now we can changes some defaults and added to proper groups to access devices or perform connections so, those are the recommended groups where the user must have in:
 
<pre><nowiki>
for u in $(ls /home); do for g in disk lp floppy audio cdrom dialout video netdev games users; do addgroup $u $g; done;done
</nowiki></pre>
 
Management of users can be made with the default '''busybox''', but for easier administration, you can add the '''libuser''' package from the testing repository:
 
<pre><nowiki>
cat > /etc/apk/repositories << EOF
http://mirror.math.princeton.edu/pub/alpinelinux/v$(cat /etc/alpine-release | cut -d'.' -f1,2)/main
http://mirror.math.princeton.edu/pub/alpinelinux/v$(cat /etc/alpine-release | cut -d'.' -f1,2)/community
http://mirror.math.princeton.edu/pub/alpinelinux/edge/testing/
EOF
 
apk update
 
apk add libuser
 
cat > /etc/apk/repositories << EOF
http://mirror.math.princeton.edu/pub/alpinelinux/v$(cat /etc/alpine-release | cut -d'.' -f1,2)/main
http://mirror.math.princeton.edu/pub/alpinelinux/v$(cat /etc/alpine-release | cut -d'.' -f1,2)/community
EOF
 
apk update
 
touch /etc/login.defs
 
touch /etc/default/useradd
</nowiki></pre>


Now we have ''libuser'' also '''can change default shell''':
By default, a newly created user will not have enough privileges for most desktop purposes.


* If you want to change the current user's shell, log in as that user and then inside their terminal session execute:: <pre>lchsh</pre>
To add newly created users to groups that may come in handy for desktop useage, you run this command as root:
* If you want to change a different user's shell, run as administration or as '''''root''''': <pre><nowiki>lchsh general</nowiki></pre>


Where "general" was the name of a created user login in previous sections.
{{cmd|for u in $(ls /home); do for g in disk lp floppy audio cdrom dialout video netdev games users; do addgroup $u $g; done;done}}


== See also: ==
== See also ==


[[Alpine_newbie_apk_packages#Users_creation_and_defaults]]
* [https://wiki.archlinux.org/title/Users_and_groups Users and groups - Archwiki]


[[Category:Newbie]]
[[Category: System_Administration]]

Latest revision as of 10:12, 3 March 2024

The root account should be used only for local administrative purposes that require elevated access permissions.

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

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).

Creating a new user

Warning: 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).


Regular user accounts can be created with:

# 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.

If a user really must be allowed to have access to the root account, the <username> can be added to the wheel group and doas ("do as") may be installed: 

# adduser -g "<username>" <username>
# adduser <username> wheel
# 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.


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


If no seat manager like elogind or seatd is being used and running, then users that want a graphical environment need the video and input groups: 

# adduser '<username>' video
# adduser '<username>' input

The above is highly discouraged. See #15409.

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 new account.

Options

adduser

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)
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.

addgroup

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

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>

Legacy

Common permission groups

This material is work-in-progress ...

Need to note a few security implications outlined on debian/wiki SystemGroups
(Last edited by WhyNotHugo on 3 Mar 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) dirves (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.

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

# adduser <username> <group>

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

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

# id <username>

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

Note that those users are created with minimal privilege settings.

User management and system access

By default, a newly created user will not have enough privileges for most desktop purposes.

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

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

See also

Retrieved from "https://wiki.alpinelinux.org/w/index.php?title=Setting_up_a_new_user&oldid=26554"