init

NFS: Setting up a basic NFS file system share

While there are many distributed file systems out there; especially with the rise of cloud & virtual computing. The Network File System or NFS protocol has by far held its title as an easy to use, fast to implement and very efficient distributed file system. In today's article I will be covering how to set up a basic NFS share. This article will assume that you have already created a file system, if not hop over to this article and then come back for the NFS steps.

iptables: Linux firewall rules for a basic Web Server

For today's article I am going to explain how to create a basic firewall allow and deny filter list using the iptables package. We will be focused on creating a filtering rule-set for a basic everyday Linux web server running Web, FTP, SSH, MySQL, and DNS services. Before we begin lets get an understanding of iptables and firewall filtering in general. What is iptables? iptables is a package and kernel module for Linux that uses the netfilter hooks within the Linux kernel to provide filtering, network address translation, and packet mangling.

When Zombies Invade Linux: What are Zombie Processes and What to do about them

Zombies don't just appear in scary movies anymore, sometimes they also appear on your Linux systems; but don't fret they are mostly harmless. What is a Zombie Process? Before we get started I wanted to first cover what exactly a Zombie process is. Linux and Unix both have the ability for a process to create a sub process otherwise known as a “Child Process”. Once a process creates a new sub process the first process then becomes a “Parent Process” as it has spawned a child process during its execution.

When it's Ok and Not Ok to use rc.local

On System V based OS's the /etc/rc.local file is executed by the init process at the end of the systems boot process. The fact that the rc.local file is executed during the boot process makes it an easy target for misuse by lazy Sysadmins. Since I started my Unix experience on FreeBSD which relies primarily on the /etc/rc.* configuration files, I've seen and shamefully contributed to my fair share of misuse in the rc.

runlevel: Check your current runlevel. Then change it

Today's commands are how you can check what runlevel your system is in and then change it. Check the current runlevel: [[email protected] tmp]# runlevel N 5 Change the current runlevel: [[email protected] tmp]# init <new_level> The run levels in Unix/Linux are used to define what state init (the parent of all processes) is in. Each distribution of Unix/Linux has different definitions of what run levels starts what processes. Usually you can find the different definitions in /etc/inittab below is the one from a fedora box.