How to change the hostname in Ubuntu
How to change hostname in Ubuntu. There are three options: temporary until the first restart and permanent by changing the hostname file or using command hostnamectl
How to open port for a specific IP address on CentOS 7
How to open port for a specific IP address on CentOS 7. Using the firewall-cmd command with add-rich-rule parameter.
How to build a LAMP stack (Linux, Apache, MySQL, PHP) on CentOS 7
How to build a LAMP stack (Linux, Apache, MySQL, PHP) on CentOS 7. The article includes the install + the firewall settings for public access.
Change ssh default port in Linux
By default, ssh listens for incoming connections on port 22. So if a hacker wants to attack your machine he will most likely scan port 22 first. Just to make an idea how important is this (from my point of view of course), before changing the default ssh port for my server I got every day 1000+ login tries for my root user. An effective (but minimal) method to protect your machine is to run ssh on non-standard port. Any unused port will work but one above 1024 is preferable.