30 Best Sources For Linux / *BSD / Unix Documentation On the Web

Posted on in Categories Debian Linux, FreeBSD, HP-UX, Linux, Linux distribution, OpenBSD, RedHat/Fedora Linux, Ubuntu Linux, UNIX last updated December 21, 2011

Man pages are written by sys-admin and developers for IT techs, and are intended more as a reference than as a how to. Man pages are very useful for people who are already familiar with Linux, Unix, and BSD operating systems. Use man pages when you just need to know the syntax for particular commands or configuration file, but they are not helpful for new Linux users. Man pages are not good for learning something new for the first time. Here are thirty best documentation sites on the web for learning Linux and Unix like operating systems.

HowTo: Use OpenBSD In the Corporate Environment

Posted on in Categories OpenBSD last updated April 20, 2011

OpenBSD has a reputation for high security and difficult operating systems for new user. But, some orginsations are using OpenBSD for everything including firewall, servers and desktop computers. This is quite impressive, from the article:

So our paid job is hacking on and deploying, maintaining, supporting… OpenBSD installations. We are also required to hack on things that can be merged back into OpenBSD itself and when it’s not possible, then we change what we did so that it can be. Of course some developments are very specific to what we do and have no place in the project’s CVS tree.

So, amongst other services, we set up and maintain several 100% OpenBSD-based infrastructures (going from the entry site firewall to the secretary’s workstation) and this is what I’m going to talk about here.

As a side note, it is important to know that we are working exclusively for Fortune 500 companies (each operating in totally different and unrelated sectors).

Read more: A Puffy in the corporate aquarium.

Download of the day: OpenBSD 4.6 CD ISO Images

Posted on in Categories Download of the day, OpenBSD last updated October 19, 2009

OpenBSD 4.6 has been released and available for download from the official website. OpenBSD is well known for record of more than ten years with only two remote holes in the default install. The OpenBSD is widely known for the quality open source code and documentation, uncompromising position on software licensing, and focus on security and code correctness.

Firewall Builder: Generate The Web Server Firewall Cluster Running Linux or OpenBSD

Posted on in Categories Iptables, Linux, OpenBSD, Security last updated March 25, 2009
Firewall Builder Logo

This article continues mini-series started with the post Introduction to Firewall Builder 4.0. This article is also available as a section in the “Firewall Builder Cookbook” chapter of Firewall Builder Users Guide 4.0.

Firewall Builder 4.0 is currently in beta testing phase. If you find it interesting after reading this post, please download and try it out. Source code archives, binary deb and rpm packages for popular Linux distributions and commercially distributed Windows and Mac OS X packages are available for download here.

In this post I demonstrate how Firewall Builder can be used to generate firewall configuration for a clustered web server with multiple virtual IP addresses. The firewall is running on each web server in the cluster. This example assumes the cluster is built with heartbeat using “old” style configuration files, but which high availability software is used to build the cluster is not really essential. I start with the setup that consists of two identical servers running Linux but in the end of the article I am going to demonstrate how this configuration can be converted to OpenBSD with CARP.

This entry is part 1 of 4 in the series Linux Firewall Cluster Configuration with Firewall Builder v4.:

Firewall Builder: Convert Linux Iptables Configuration to OpenBSD and PF

Posted on in Categories Iptables, Linux, OpenBSD, Security last updated March 25, 2009

Lets see how much effort it is going to take to convert this configuration to entirely different firewall platform – PF on OpenBSD. There are different ways to do this. I could make a copy of each member firewall (linux-test-1 and linux-test-2), set platform and host OS in the copy to PF and OpenBSD and then create new cluster object. This would be a sensible way because it preserves old objects which helps to roll back in case something does not work out. However, to make the explanation shorter, I am going to make the changes in place by modifying existing objects.

Linux: Should You Use Twice the Amount of Ram as Swap Space?

Posted on in Categories data center, Debian Linux, fedora linux, File system, FreeBSD, Gentoo Linux, kernel, Linux, Linux desktop, Linux laptop, OpenBSD, RedHat/Fedora Linux, Solaris, Storage, Suse Linux, Tuning, Ubuntu Linux, UNIX last updated November 19, 2008

Linux and other Unix-like operating systems use the term “swap” to describe both the act of moving memory pages between RAM and disk, and the region of a disk the pages are stored on. It is common to use a whole partition of a hard disk for swapping. However, with the 2.6 Linux kernel, swap files are just as fast as swap partitions. Now, many admins (both Windows and Linux/UNIX) follow an old rule of thumb that your swap partition should be twice the size of your main system RAM. Let us say I’ve 32GB RAM, should I set swap space to 64 GB? Is 64 GB of swap space really required? How big should your Linux / UNIX swap space be?