The Arch Linux based distro that runs upon any Linux distros without root access.

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Table of Contents

• Description
• Quickstart
• Installation
• Dependencies
• Advanced usage
• Internals
• Troubleshooting
• [More documentation](#more documentation)
• License
• Author
• WWW

JuNest (Jailed User NEST) is a lightweight Arch Linux based distribution that allows to have an isolated GNU/Linux environment inside any generic host GNU/Linux OS and without the need to have root privileges for installing packages.

JuNest contains mainly the package managers (called pacman and yaourt) that allows to access to a wide range of packages from the Arch Linux repositories.

The main advantages on using JuNest are:

• Install packages without root privileges.
• Isolated environment in which you can install packages without affecting a production system.
• Access to a wide range of packages in particular on GNU/Linux distros that may contain limited repositories (such as CentOS and RedHat).
• Available for x86_64, x86 and ARM architectures but you can build your own image from scratch too!
• Run on a different architecture from the host OS via QEMU
• All Arch Linux lovers can have their favourite distro everywhere!

JuNest follows the Arch Linux philosophy.

There are three different ways you can run JuNest:

• As normal user - Allow to make basic operations: junest

• As fakeroot - Allow to install/remove packages: junest -f

• As root - Allow to have fully root privileges inside JuNest environment (you need to be root for executing this): junest -r

If the JuNest image has not been downloaded yet, the script will download the image and will place it to the default directory ~/.junest. You can change the default directory by changing the environment variable JUNEST_HOME.

If you are new on Archlinux and you are not familiar with pacman package manager visit the pacman rosetta page.

JuNest can works on GNU/Linux OS with kernel version greater or equal 2.6.0 (JuNest was not tested on kernel versions older than this) on 64 bit, 32 bit and ARM architectures.

Just clone the JuNest repo somewhere (for example in ~/junest):

git clone git://github.com/fsquillace/junest ~/junest
export PATH=~/junest/bin:$PATH

If you are using an Arch Linux system you can, alternatively, install JuNest from the AUR repository:

yaourt -S junest-git
export PATH=/opt/junest/bin:$PATH

Alternatively, another installation method would be to directly download the JuNest image and place it to the default directory ~/.junest:

ARCH=<one of "x86_64", "x86", "arm">
mkdir ~/.junest
curl https://dl.dropboxusercontent.com/u/42449030/junest/junest-${ARCH}.tar.gz | tar -xz -C ~/.junest
export PATH=~/.junest/opt/junest/bin:$PATH

JuNest comes with a very short list of dependencies in order to be installed in most of GNU/Linux distributions. The needed executables in the host OS are:

• bash
• chown (for root access only)
• ln
• mkdir
• rm
• tar
• uname
• wget or curl

The minimum recommended linux kernel is 2.6.0+

You can build a new JuNest image from scratch by running the following command:

junest -b [-n]

The script will create a directory containing all the essentials files in order to make JuNest working properly (such as pacman, yaourt and proot). The option -n will skip the final validation tests if they are not needed. Remember that the script to build the image must run in an Arch Linux OS with arch-install-scripts, package-query, git and the base-devel packages installed. To change the build directory just use the JUNEST_TEMPDIR (by default /tmp).

After creating the image junest-x86_64.tar.gz you can install it by running:

junest -i junest-x86_64.tar.gz

For more details, you can also take a look at junest-builder that contains the script and systemd service used for the automatic building of the JuNest image.

Related wiki page:

• How to build a JuNest image using QEMU

The following command will download the ARM JuNest image and will run QEMU in case the host OS runs on either x86_64 or x86 architectures:

$> JUNEST_HOME=~/.junest-arm junest -a arm -- uname -m
armv7l

To bind a host directory to a guest location, you can use proot arguments:

junest -p "-b /mnt/mydata:/home/user/mydata"

Check out the proot options with:

junest -p "--help"

Although JuNest has not been designed to be a complete container, it is even possible to virtualize the process tree thanks to the systemd container. The JuNest containter allows to run services inside the container that can be visible from the host OS through the network. The drawbacks of this are that the host OS must use systemd as a service manager, and the container can only be executed using root privileges.

To boot a JuNest container:

sudo systemd-nspawn -bD ~/.junest

Related wiki page:

• How to run junest as a container
• How to run services using Systemd

There are two main chroot jail used in JuNest. The main one is proot which allows unprivileged users to execute programs inside a sandbox and jchroot, a small and portable version of arch-chroot which is an enhanced chroot for privileged users that mounts the primary directories (i.e. /proc, /sys, /dev and /run) before executing any programs inside the sandbox.

##Automatic fallback to classic chroot## If jchroot fails for some reasons in the host system (i.e. it is not able to mount one of the directories), JuNest automatically tries to fallback to the classic chroot.

##Automatic fallback for all the dependent host OS executables## JuNest attempt first to run the executables in the host OS located in different positions (/usr/bin, /bin, /usr/sbin and /sbin). As a fallback it tries to run the same executable if it is available in the JuNest image.

##Automatic building of the JuNest images## The JuNest images are built every week so that you can always get the most updated package versions.

##Static QEMU binaries## There are static QEMU binaries included in JuNest image that allows to run JuNest in a different architecture from the host system. They are located in /opt/qemu directory.

##Cannot use AUR repository##

Q: Why do I get the following error when I try to install a package with yaourt?

Cannot find the gzip binary required for compressing man and info pages.

A: JuNest comes with a very basic number of packages. In order to install packages using yaourt you may need to install the package group base-devel that contains all the essential packages for compiling source code (such as gcc, make, patch, etc):

pacman -S base-devel

##Kernel too old##

Q: Why do I get the error: "FATAL: kernel too old"?

A: This is because the executable from the precompiled package cannot properly run if the kernel is old. You may need to specify the PRoot -k option if the guest rootfs requires a newer kernel version:

junest -p "-k 3.10"

In order to check if an executable inside JuNest environment can be compatible with the kernel of the host OS just use the file command, for instance:

file ~/.junest/usr/bin/bash
ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked
(uses shared libs), for GNU/Linux 2.6.32,
BuildID[sha1]=ec37e49e7188ff4030052783e61b859113e18ca6, stripped

From the output you can see what is the minimum recommended Linux kernel version.

##SUID permissions##

Q: Why I do not have permissions for ping?

ping www.google.com
ping: icmp open socket: Operation not permitted

A: The ping command uses suid permissions that allow to execute the command using root privileges. The fakeroot mode is not able to execute a command set with suid, and you may need to use root privileges. There are other few commands that have suid permission, you can list the commands from your JuNest environment with the following command:

find /usr/bin -perm +4000

##No characters are visible on a graphic application##

Q: Why I do not see any characters in the application I have installed?

A: This is probably because there are no fonts installed in the system.

To quick fix this, you can just install a fonts package:

pacman -S gnu-free-fonts

##Differences between filesystem and package ownership##

Q: Why do I get warning when I install a package using root privileges?

pacman -S systat
...
warning: directory ownership differs on /usr/
filesystem: 1000:100  package: 0:0
...

A: In these cases the package installation went smoothly anyway. This should happen every time you install package with root privileges since JuNest will try to preserve the JuNest environment by assigning ownership of the files to the real user.

##No servers configured for repository##

Q: Why I cannot install packages?

pacman -S lsof
Packages (1): lsof-4.88-2

Total Download Size:    0.09 MiB
Total Installed Size:   0.21 MiB

error: no servers configured for repository: core
error: no servers configured for repository: community
error: failed to commit transaction (no servers configured for repository)
Errors occurred, no packages were upgraded.

A: You need simply to update the mirrorlist file according to your location:

# Uncomment the repository line according to your location
nano /etc/pacman.d/mirrorlist
pacman -Syy

There are additional tutorials in the JuNest wiki page.

Copyright (c) 2012-2015

This program is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Filippo Squillace [email protected]

https://github.com/fsquillace/junest