The hostname command is a basic tool in Linux systems that allows you to query or set the computer name. In Linux systems, every machine has a unique name, which we call "hostname". This name allows devices to be identified and accessed within the network. The hostname command can be used to view or change the settings of the current hostname. This command is particularly useful when diagnosing network problems and configuring servers and other network devices.

In the world of modern information technology, the use of accurate time is a critical aspect. In today's Linux operating systems, there are many solutions to ensure that our system's clock is always synchronized with world time. In this short description, we will see how to set the date, the exact time and our time zone manually, and how to activate time synchronization with the Internet.

In this description, we will install the PHP 8.2 version on a Debian system, set the default PHP versions, set it as an optional PHP version in the ISPConfig control panel, set it in the required storage locations and finally check the PHP operation on a Drupal and a WordPress site.

Our websites are constantly under attack from the outside world. The vast majority of these are done by robots, which try to discover the weak points of the websites running on the server. Some of the robots with this purpose try to do this by making various seemingly random HTTP requests to our websites, most of which are directed to non-existent URL addresses. As a result, our server responds with a 404 HTTP response code. In this description, we will look at how to ban the large number of attempts resulting in 404 and other 4xx HTTP response codes using Fail2Ban.

After updating ISPConfig, not all services restarted. In this case, the Dovecot POP3/IMAP mail server and even Postfix threw warnings. Although we fixed these errors earlier, our settings were overwritten again during the ISPConfig update. In this troubleshooter, on the one hand, we fix "Address family not supported by protocol" type errors that cause the service to be inoperable, and we also make their permanent settings so that they remain even after further ISPConfig updates.

By using the HSTS header, we can make our websites more secure against man-in-the-middle attacks. In this short description, we will see how we can set this HTTP header in our Apache-based LAMP or ISPConfig server environment.

The HTTP/2 or HTTP2.0 protocol enables faster web services with less data traffic. Although the protocol created in 2015 has been widespread for quite a few years, it is not turned on by default in the majority of web servers due to compatibility reasons. Among other things, it does not support the outdated mod_php Apache module, which in turn still operates many old websites, so enabling and enabling it is left to system administrators. In this short description, we will see how we can enable the use of the HTTP/2 protocol on Apache web servers that still use the old HTTP/1.1 protocol.

There are several ways to manage web servers and other servers remotely, of which SSH is the most common command line solution. The SSH protocol communicates over an encrypted channel between the server and the client. Like all similar communications, SSH transmits data through a specific port, which by default is the well-known tcp port 22. Since the function of this port is known to many people, it exposes the servers to regular attacks. This is usually avoided - or at least to reduce the number of attempts - by switching this well-known port to another, unknown port number, which can only be detected externally by port scanning, which is a more time-consuming task.
In this write-up, we will look at how to change SSH's well-known TCP port 22 to a unique port number to minimize the number of attack attempts via SSH.

UCW (Uncomplicated Firewall) is an easy-to-use netfilter firewall management program. It uses a command line interface that consists of a few simple commands and uses iptables for configuration, so it is the frontend of iptables. In this description we will look at the installation and basic use and configuration of the UFW firewall, the steps of which I will perform on a minimal Debian 11 server.