Types of Firewall and DMZ Architectures

In the world of expensive commercial firewalls (the world in which I earn my living), the term "firewall" nearly always denotes a single computer or dedicated hardware device with multiple network interfaces. This definition can apply not only to expensive rack-mounted behemoths, but also to much lower-end solutions: network interface cards are cheap, as are PCs in general.
This is different from the old days, when a single computer typically couldn't keep up with the processor overhead required to inspect all ingoing and outgoing packets for a large network. In other words, routers, not computers, used to be one's first line of defense against network attacks.read more.

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Fixing Unix/Linux/POSIX Filenames

Traditionally, Unix/Linux/POSIX filenames can be almost any sequence of bytes, and their meaning is unassigned. The only real rules are that "/" is always the directory separator, and that filenames can't contain byte 0 (because this is the terminator). Although this is flexible, this creates many unnecessary problems. In particular, this lack of limitations makes it unnecessarily difficult to write correct programs (enabling many security flaws), makes it impossible to consistently and accurately display filenames, causes portability problems, and confuses users. more ....

Noisy Neighbor Detection with eBPF.

T he Compute and Performance Engineering teams at Netflix regularly investigate performance issues in our multi-tenant environment. The first step is determining whether the problem originates from the application or the underlying infrastructure. One issue that often complicates this process is the "noisy neighbor" problem. On Titus, our multi-tenant compute platform, a "noisy neighbor" refers to a container or system service that heavily utilizes the server's resources, causing performance degradation in adjacent containers. We usually focus on CPU utilization because it is our workloads’ most frequent source of noisy neighbor issues, read more

Backing up MySQL data.

Backing up files and directories is relatively easy; databases, however, have some special quirks that you need to address. Our examples use MySQL, but the same principles apply to PostgreSQL and other relational databases. This article is excerpted from O'Reilly's recently published book Linux System Administration .

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