LinuxSecurity.com

We've all run into UFW on Linux systems that were already in use. When firewall problems show up, they almost never show up in new or surprising ways. We at Linux Security want to help other admins recognize the kind of UFW problem they're dealing with before they start changing rules or chasing symptoms. This page isn't about fixes yet. The goal is to help you recognize the category of issue so you know where to look next.

For a long time, Linux malware followed a familiar pattern. A compromised host. A binary written to disk. Persistence through cron, systemd, or a quiet modification that survived reboots. If you hardened the system and watched for changes, you felt reasonably in control. That model no longer matches how Linux is actually run. Modern Linux malware increasingly assumes it is landing in environments where hosts are disposable, workloads are short-lived, and the real authority sits somewhere above the operating system.

On most long-running Linux servers, UFW rules don't get removed; they get forgotten. Services change, ports shift, packages come and go, and the firewall stops matching what the box is actually doing. You only notice when you audit it, or when something breaks and nobody remembers why a port was ever opened.

Snort 3 flaws don't matter because they are unusual. They matter because they are predictable.

Tor Browser is a privacy-focused web browser that routes traffic through the Tor network to obscure a user's identity and destination''and that design has direct implications for Linux security teams. It's built to limit tracking, resist surveillance, and reduce visibility into browsing activity. On a Linux endpoint, that means user activity can intentionally bypass many of the controls and assumptions your security stack relies on.