Chroot is the operation of changing the root directory on Unix-like operating systems. A program launched with a modified root directory will only have access to the files contained in this directory.

Dependency Installation

The first thing to do is run the following installation commands, which will be explained later

apt-get install binutils debootstrap

Then you should choose a place to configure chroot. We recommend using will use /var/chroot directory

Create the necessary directories

You need a create chroot folder

mkdir -p /var/chroot

This completes the setup of the preliminary steps. Next, you need to copy all the commands and their dependencies. This requires a command interpreter, so let’s copy bash.

mkdir -p /var/chroot/bin
cp /bin/bash /var/chroot/bin

Having looked at all the dependencies, you can run the following program

ldd /bin/bash

If you are using (for example) a 32-bit version, it will look just like this:

linux-gate.so.1 =>  (0xb773e000)
libtinfo.so.5 => /lib/i386-linux-gnu/libtinfo.so.5 (0xb7718000)
libdl.so.2 => /lib/i386-linux-gnu/libdl.so.2 (0xb7714000)
libc.so.6 => /lib/i386-linux-gnu/libc.so.6 (0xb75c3000)
/lib/ld-linux.so.2 (0xb773f000)

The following is the copying of files:

mkdir -p /var/chroot/lib 
mkdir -p /var/chroot/lib/i386-linux-gnu
cp /lib/i386-linux-gnu/libtinfo.so.5 /var/chroot/lib/i386-linux-gnu
cp /lib/i386-linux-gnu/libdl.so.2 /var/chroot/lib/i386-linux-gnu
cp /lib/i386-linux-gnu/libc.so.6 /var/chroot/lib/i386-linux-gnu

Testing the environment

Checking the bash setting

chroot /var/chroot

If you need to connect to the network in chroot, you will need to run the following commands:

mkdir -p /var/chroot/etc
cp /etc/resolv.conf /var/chroot/etc
cp /etc/gai.conf /var/chroot/etc