Have you ever installed packages from third party repositories to later realize that it was not the best idea? No? Well – I have.

But from now on, I wont do it. And instead utilize chroot!

In this section, we'll cover how you do it on your Debian-based system aswell as on Fedora.

Install the package debootstrap

apt update; apt install debootstrap

Or if you are on Fedora:

dnf install debootstrap

Now, create a catalogue anywhere of your choosing, for example in /srv

mkdir /srv/chroot

Great. Now depending on what you want. Perform any of the following:

debootstrap bullseye /srv/chroot http://ftp.us.debian.org/debian

debootstrap  jammy /srv/chroot http://archive.ubuntu.com/ubuntu

You should see it pull down all the packages needed for the distro to start, and when it is complete – you can enter the chroot:

chroot /srv/chroot

That's it! Now you can install, test or compile your packages as usual.

And when you are done, you can simply remove the catalogue and start fresh – if you want.

Here is a quick demo of the actual process:

#linux #chroot #sysadmin #debian #ubuntu #fedora

This short writeup will guide you on how to do it on Debian-based and Fedora systems.

We begin with installing posfix and the required packages for authentication.

First – doublecheck that your machine has a Fully Qualified Domain Name set in the hostfile, this will remove alot of headaches from you in the future.

My machine is named “T15.domain.tld” – so emails will be arriving from “user@T15.domain.tld”.

Debian:

apt-get install postfix mailutils libsasl2-2 libsasl2-modules

Fedora:

dnf install postfix mailx mailx cyrus-sasl cyrus-sasl-plain

Next, we will create the sasl-password file and hash it:

echo "[relay.domain.tld]:587 username:password" > /etc/postfix/sasl
postmap /etc/postfix/sasl

Great, now we have to tell postfix that all emails sent via it should be relayed throu the smtp-relay:

relayhost = [relay.domain.tld]:587
smtp_use_tls = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

Restart postfix and check the log, so everything looks good.

Test your setup:

echo "This is a test" | mail -s "Just a test" destination_email@domain.tld

You can check the status of the mailqueue with the command mailq.

And that's about it!

#linux #postfix #smtp #sysadmin #email