- Lab
-
Libraries: If you want this lab, consider one of these libraries.
- Cloud
- Security

Email Services: TLS Configuration with Postfix
Securing `postfix` is an important part of managing an email server that is addressable on the Internet these days. One step in doing so is making sure that all connections use TLS. This hands-on lab will allow you to build a certificate chain and configure `postfix` to use that chain to encrypt data.

Lab Info
Table of Contents
-
Challenge
Generate the SSL Certificate
- We need to create the key and CSR (Certificate Signing Request). We'll also need to work as the root user, so elevating now will save time.
sudo -i openssl req -nodes -newkey rsa:2048 -keyout privatekey.key -out mail.csr
This will ask for a bunch of information. Since we’re doing a self-signed certificate, we don’t need to fill all of it out — accept the defaults.
- Now we need to sign that request using the key we just generated.
openssl x509 -req -days 365 -in mail.csr -signkey privatekey.key -out secure.crt
- Now we copy the key and certificate over to where postfix can use them.
cp {privatekey.key,secure.crt} /etc/postfix
-
Challenge
Configure Postfix to use TLS
- Run:
vim /etc/postfix/main.cf
- Insert these lines at the end:
smtpd_use_tls = yes smtpd_tls_cert_file = /etc/postfix/secure.crt smtpd_tls_key_file = /etc/postfix/privatekey.key smtp_tls_security_level = may
- Restart postfix:
systemctl restart postfix
- Test the configuration:
openssl s_client -connect localhost:25 -starttls smtp
- Scroll back and look at the certificate information. If it matches what you put in, everything worked correctly!
About the author
Real skill practice before real-world application
Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.
Learn by doing
Engage hands-on with the tools and technologies you’re learning. You pick the skill, we provide the credentials and environment.
Follow your guide
All labs have detailed instructions and objectives, guiding you through the learning process and ensuring you understand every step.
Turn time into mastery
On average, you retain 75% more of your learning if you take time to practice. Hands-on labs set you up for success to make those skills stick.