Linux admins,

Firewalls are basic until they break your access or silently leave gaps in your defenses. On Ubuntu servers, UFW sits right at the edge of the kernel and your management plane, and small mistakes like assuming what’s bound where or enabling rules in the wrong order can lock you out or expose critical services without you knowing.

Today, we peel back the common setbacks admins hit when protecting SSH and other services with UFW, and explain the practical moves that separate stable firewalls from brittle ones. If you think “just enabling UFW” is enough, read on. The traps are subtle, and they matter!

Yours in Open Source,

Dv Signature Newsletter 2024 Esm W150

Dave Wreski

LinuxSecurity Founder

Ubuntu: UFW Important Firewall Rules for Secure SSH and Database Access

2.Motherboard Esm W400

UFWis a front-end foriptablesthat applies firewall policy directly on an Ubuntu server, close to the services that accept traffic.

On real systems, exposure is shaped by more than open ports. A service binds to an address, that address maps to an interface, and that interface may sit behind cloud security groups, VPNs, or container networks.UFWenforces policy inside that path, which is why rules that look correct can still fail once traffic hits the server.

The aim is to align those layers. You start by identifying what is listening and where, then applyUFWrules that match the server’s role and expected access. SSH, web services, and databases each behave differently, and the firewall only holds when those differences are made explicit.

Learn About Firewall Rules>>

“MongoBleed” MongoDB Memory Leak Under Active Exploitation — Distros Lag on Updates

32.Lock Code Circular Esm W400

MongoBleed, tracked as CVE-2025-14847, is a high-severity flaw in MongoDB that allows unauthenticated attackers to read small pieces of a server’s memory. In simple terms, a remote client can ask MongoDB to process a malformed compressed message, and the database may respond with extra bytes it never intended to send.

Those extra bytes come from memory the process was already using. No login is required, and no unusual configuration is needed. The issue sits in a pre-authentication code path that most administrators never have reason to think about.

Learn About MongoBleed>>