≡ Menu

system administration

The Free Technology Academy (FTA) has released excellent book called "The GNU/Linux operating system", the main contents are related with system administration. You will learn how to install and configure several computer services, and how to optimise and synchronise the resources using GNU/Linux.
[click to continue…]

Excellent article! It explains how programs are laid out in memory.

From the blog post:

Memory management is the heart of operating systems; it is crucial for both programming and system administration. In the next few posts I’ll cover memory with an eye towards practical aspects, but without shying away from internals. While the concepts are generic, examples are mostly from Linux and Windows on 32-bit x86. This first post describes how programs are laid out in memory. Each process in a multi-tasking OS runs in its own memory sandbox. This sandbox is the virtual address space, which in 32-bit mode is always a 4GB block of memory addresses.

=> Anatomy of a Program in Memory

Windows PowerShell vs UNIX BASH Shell

Shell scripting is fun. It is useful to create nice (perhaps ugly) things (read as solutions) in shell scripting. Now Windows got Powershell. But how does PowerShell measure up to traditional shells like Bash?

Linux Magazine's Marcus Nasarek compares Windows Vista PowerShell with Bash:

Both Bash and the Windows Vista PowerShell include commands for navigating directories, managing files, and launching other programs. System administration is an important duty for the shell, and Bash and PowerShell are equipped to help manage systems from the command prompt. Whereas Bash typically relies on a combination of newer tools and classic Unix utilities, the PowerShell has its own set of command-line programs. Windows refers to PowerShell commands as cmdlets. The PowerShell cmdlet called Get-Process is a counterpart to ps, and the cmdlet Get-Content corresponds to less. PowerShell differs significantly from previous Windows command shells.

Some time I need to work with on Windows Servers and I find this article interesting. However, I prefer to use Perl or Python for complicated stuff.

Understanding Forensics

Forensics is the art and science of applying computer science to aid the legal process. Linux journal has published a nice introduction to Forensics:

A break-in can happen to any system administrator. Find out how to use Autopsy and Sleuthkit to hit the ground running on your first forensics project.

There are certain aspects to system administration that you can learn only from experience. Computer forensics (among other things the ability to piece together clues from a system to determine how an intruder broke in) can take years or even decades to master. If you have never conducted a forensics analysis on a computer, you might not even know exactly where to start. In this guide, I cover how to use the set of forensics tools in Sleuthkit with its Web front end, Autopsy, to organize your first forensics case.

One of the most common scenarios in which you might want to use forensics tools on a system is the case of a break-in. If your system has been compromised, you must figure out how the attacker broke in so you can patch that security hole. Before you do anything, you need to make an important decision—do you plan to involve law enforcement and prosecute the attacker?

=> Introduction to Forensics

Humor: Know your System Administrator

The joke on this page was obtained from the FSF's email archives of the GNU Project:

There are four major species of Unix sysad:
1.The TECHNICAL THUG. Usually a systems programmer who has been forced into system administration; writes scripts in a polyglot of the Bourne shell, sed, C, awk, perl, and APL.

2.The ADMINISTRATIVE FASCIST. Usually a retentive drone (or rarely, a harridan ex-secretary) who has been forced into system administration.

3.The MANIAC. Usually an aging cracker who discovered that neither the Mossad nor Cuba are willing to pay a living wage for computer espionage. Fell into system administration; occasionally approaches major competitors with indesp schemes.

4.The IDIOT. Usually a cretin, morpohodite, or old COBOL programmer selected to be the system administrator by a committee of cretins, morphodites, and old COBOL programmers.
HOW TO IDENTIFY YOUR SYSTEM ADMINISTRATOR:

Generally I use Perl and Shell script for automation or to make system administration easier for me. Python is an interpreted, interactive, object-oriented programming language that combines remarkable power with very clear syntax. Python runs on Windows, Linux/Unix, Mac OS X, OS/2, Amiga, Palm Handhelds, and Nokia mobile phones.

You can easily adopt Python to manage UNIX and Linux systems while incorporating concepts of good program design. Python is an easy-to-learn, open source scripting language that lets system administrators do their job more quickly. It can also make tasks more fun:

As a system administrator, you run across numerous challenges and problems. Managing users, disk space, processes, devices, and backups can cause many system administrators to lose their hair, good humor, or sanity. Shell scripts can help, but they often have frustrating limitations. This is where a full-featured scripting language, such as Python, can turn a tedious task into an easy and, dare I say it, fun one.

The examples in this article demonstrate different Python features that you can put to practical use. If you work through them, you'll be well on your way to understanding the power of Python.

=> Python for system administrators

Q. I am using Ubuntu Linux and I would like to know how to create alias for eth0 so that I can have multiple IP address?

A. To create alias for eth0 use ifconfig command. It is use to configure a network interface and aliases.

Assuming that your eth0 IP is 192.168.1.10 and you would like to create an alias eth0:0 with IP 192.168.1.11. Type the following command:

sudo ifconfig eth0:0 192.168.1.11 up

OR

sudo /sbin/ifconfig eth0:0 192.168.1.11 up

Verify that alias is up and running using following two command(s):

/sbin/ifconfig
ping 192.168.1.11
ping your-getway-ip

Permanent configuration

Your ethernet configuration is located in a file called /etc/network/interfaces. If you reboot system you will lost your alias. To make it permanent you need to add it network configuration file:

gksudo gedit /etc/network/interfaces

OR

sudo vi /etc/network/interfaces

Append the following configuration:

auto eth0:0
iface eth0:0 inet static
name Ethernet alias LAN card
address 192.168.1.11
netmask 255.255.255.0
broadcast 192.168.1.255
network 192.168.1.0

Save the file and restart system or restart the network:

sudo /etc/init.d/networking restart

Please note that you can also use graphical tools located at System > Administration > Networking menu. Or use the following GUI tool to setup aliases, hostname, dns settings etc:

sudo network-admin

If you want more network aliases, use eth0:1, eth0:2, eth0:N (max upto 254).

See also: