One effective way to protect your server from threats is by restricting access to only trusted entities. For example, if you are using a proxy service like Cloudflare, you can configure your server’s firewall to only accept requests from Cloudflare IPs for HTTP (port 80) and HTTPS (port 443) services. This article will discuss practical steps to achieve this using firewalld. Why Choose This Configuration? Cloudflare acts as a proxy between users and your server. By limiting access to only Cloudflare IPs, direct requests from other sources (that do not go through Cloudflare) will be rejected by the firewall, thus preventing potential attacks such as DDoS. ...

Increasing Disk Size on a QEMU Disk Image A disk image is a file that contains the data of a virtual disk, often used to simulate computational environments in virtualization. In the context of QEMU (Quick Emulator), the two most commonly used disk image formats are QCOW2 (QEMU Copy-On-Write version 2). One important concept in disk images is virtual size. Virtual size refers to the total disk capacity that is visible to the guest operating system (guest OS). The virtual size represents the maximum storage space that can be utilized by the guest OS, even though the disk image file itself may not use all of that space on the host. ...

When using a Linux distribution like Debian, you may have encountered issues related to the locale. One common error that often appears is the following message: apt-listchanges: Can't set locale; make sure $LC_* and $LANG are correct! perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LC_TIME = "id_ID.UTF-8", LC_MONETARY = "id_ID.UTF-8", LC_ADDRESS = "id_ID.UTF-8", LC_TELEPHONE = "id_ID.UTF-8", LC_NAME = "id_ID.UTF-8", LC_MEASUREMENT = "id_ID.UTF-8", LC_IDENTIFICATION = "id_ID.UTF-8", LC_NUMERIC = "id_ID.UTF-8", LC_PAPER = "id_ID.UTF-8", LANG = "C.UTF-8" are supported and installed on your system. perl: warning: Falling back to a fallback locale ("C.UTF-8"). This message indicates that the system is unable to set the requested locale (id_ID.UTF-8) because the locale has not been installed or configured properly. This issue generally occurs when the locale settings in environment variables (LC_*, LANG, etc.) do not match the locales available on the Debian system. ...

In the world of virtualization computing, the term CPU steal often appears as one of the important metrics that need to be monitored. Especially if you are using a VPS (Virtual Private Server) service, understanding what CPU steal is and how it impacts performance is crucial for maintaining your server’s efficiency. What is CPU Steal? CPU steal is the percentage of time allocated by the hypervisor (the software that manages virtualization) to the physical processor for handling tasks from other virtual machines (VMs) within a virtualized environment. In other words, CPU steal occurs when the physical CPU is busy handling requests from other VMs, causing your VM to “wait its turn” to gain access to the CPU. This means that even though the CPU on your VM may not appear to be working hard, there’s a possibility that the CPU is being used by another VM in the same system. The higher the CPU steal value, the greater the impact on the performance of applications or services running on your VPS. ...

iperf3 is an open-source tool used to measure network bandwidth and analyze connection performance. With iperf3, we can perform real-time network speed tests between two devices. Install iperf3 Installing iperf3 on the client and server. Debian/Ubuntu sudo apt install iperf3 CentOS/RHEL sudo dnf install iperf3 Firewall Configuration iperf3 uses port 5201. Ensure this port is open on the server so the client can connect. If using ufw as the firewall, open port 5201 with the following command: ...