If you are using dovecot and postfix with a SQLite backend you can easily add a new user account with just a few steps. If you are using a different database such as MySQL, the following steps should be easily transferrable. We are assuming this is a new user account for an already configured and existing domain name on your mail server. First we’ll need to generate a new password using SHA512-CRYPT encryption using the doveadm utility.

One of the critical components of hosting a mail server and ensuring that your emails get delivered to inboxes is DKIM. DomainKeys Identified Mail is an email authentication protocol that allows receiving mail servers to verify that the email message truly came from the domain that it claims to have arrived from. DKIM uses public-key cryptography to enable senders to sign emails, and together with DNS, recipients can verify the signatures.

In case you need to quickly ban a list of IP addresses from connecting to your server, iptables is perfect for the job. iptables is a user-space firewall that can control incoming and outgoing connections with policies and filter rules. Blocking ingress from a single IP is easily done with a single iptables rule. We can use this same command to automate the creation of many rules with a bash script that will read our list of IP addresses from a file.

When running an Apache web server, you can find yourself in a situation where you need to capture and log POST data to do some analysis and perhaps to investigate a bad actor to determine a fingerprint pattern. This can be done with the mod_security module, which is a powerful web application firewall that also provides HTTP traffic monitoring, logging and analysis capabilities. Although this can also be done with mod_dumpio, I wanted to be able to create rulesets to shape the traffic after doing the analysis.

The Tuya UFO-R1 is a smart infrared universal remote control from Tuya, a company known for mass production and distribution of smart devices under various brand names. Inside the device is a TYWE3S Wi-Fi module, which is based on the ESP8266 microcontroller from Espressif Systems. This specific microchip comes with 1 MiB of built-in flash and a full TCP/IP stack. The low-cost and very few external components on the module make it attractive platform for many smart device manufacturers.