If you have ever jumped between Linux distributions, you have probably noticed something confusing: Ubuntu talks about ufw, Red Hat tells you to use firewall-cmd, Debian ships with nothing enabled at all, and old tutorials keep mentioning iptables. Are these…
What Is nf_tables? nf_tables is the modern Linux packet filtering framework. It is the successor to iptables and is built into the Linux kernel. Its job is simple: decide what to do with every network packet that passes through your…
These are two of the original ICMP message types defined in RFC 792 (1981), alongside echo (ping) and destination-unreachable. They were designed for clock synchronization across a network, back before NTP existed. What they do The reply carries three 32-bit…
CVE-1999-0524 is an information-disclosure finding: the host responds to ICMP timestamp requests (type 13) with timestamp replies (type 14), which can leak the system clock and (historically) help an attacker with time-based attacks. The fix is simply to drop both…
Most Linux engineers learn SSH local port forwarding early in their careers. You have a database running on a remote server, and you want to access it from your laptop. Easy: A few seconds later, the remote PostgreSQL database magically…
In a standard Linux environment, directory permissions can sometimes be counterintuitive. By default, any user with write access to a directory has the power to delete or rename any file within that directory, regardless of who owns the file or…
If you are managing a Red Hat Enterprise Linux (RHEL) server, you likely face the challenge of ensuring only trusted software runs on your system. You might find yourself in a scenario where a user accidentally downloads an untrusted script…
Setting up a server often involves getting the network identity right. You might find yourself in a scenario where you have manually set a temporary IP using a legacy command, only to realize the configuration vanished after a simple reboot.…
Python development relies heavily on external libraries to handle complex tasks like data analysis or web scraping. You might encounter a scenario where you try to run a script only to receive an “ImportError,” or you may need to deploy…
Setting up a new environment often requires installing specific tools to meet your project goals. You might find yourself needing to install a web server like Apache to host a website, or a network scanner like Nmap to audit your…
