Visual Representations Of Linux File Systems

Posted on in Categories File system, Howto, kernel, Linux last updated June 16, 2009

This is an interesting visualization techniques for software analysis. From the article:

Despite being a very important part of any operating system, file systems tend to get little attention. Linux has three editions for Linux Device Drivers, another three for Understanding the Linux Kernel and two for Linux Kernel Development. The first is a detail analysis of one particular Linux Kernel tree and the second is a shorter one done over a large number of file systems from Linux Kernel 2.6.0 to 2.6.29. After that there is a small section that shows some aspects of the BSD family. After conclusions there is an appendix consisting of three things: the first one explains how the file systems for Linux were compiled, the second one shows timelines for the releases of Linux Kernel, FreeBSD, NetBSD and OpenBSD; the last is a detailed map of the external symbols of the kernel modules analyzed in the second section.

A Visual Expedition Inside the Linux File Systems

Howto monitor OpenBSD PF firewall for performance

Posted on in Categories Monitoring, OpenBSD, Security, UNIX last updated July 3, 2007

Packet Filter aka PF is OpenBSD’s system for filtering TCP/IP traffic / NAT software. I always like the simplicity offered by PF firewall. There is a new article that explains the PF performance monitoring:

The PF (packet filter) firewall package was introduced in OpenBSD 3.0, and has since been ported to the FreeBSD and NetBSD Operating Systems. PF contains a stateful packet inspection engine, the ability to replicate state information to a backup firewall, a flexible self optimizing rule engine, QOS support, and the ability to collect performance metrics. These metrics can be useful for gauging the performance of a firewall platform, and provide a way to trend firewall performance over time. This article will describe several utilities that can be used to monitor the health and performance of a PF firewall.

On a related note you may find our FreeBSD firewall startup guide quite useful.

Monitoring PF firewalls for health and performance []