Mandriva 2009.1: Network Applet

There are a lot of reasons for choosing a Distro, one of them may be features that are available for setting up and administering your network configuration.  Mandriva 2009.1 offers a number of administrative tools that work well and are easy to use.  One of those features is the network Applet.  Go to system/Administration and NetApplet to start the applet and place it on your panel.  Here you can see the Applet with a check mark indicating that networking is up and functioning.

If you right click the Applet you will get several options:

Disconnect
Monitor Network
Interactive Firewall
Configure Network
VPN
Settings
Help

What is nice about this is you have everything at your fingertips.  If you select Monitor Network you will get this screen.  This will allow you to Monitor or Configure.

If you choose Monitor you will be able to see the activity on the network that is current and also an average.  This gives you a good idea about what is actually happening on your network for troubleshooting.

If you choose to configure you can set up DHCP or you can set up Manual IP Address.

Advanced settings allow you to turn off IPV6 for instance that can give you some issues.

Summary:

It is refreshing to use a network tool that works and provides so many options in one place.  This is an excellent reason for considering Mandriva.

Using the Shell

The Shell is the Linux equivalent of the CMD screen in Windows. Where it differs is that in Linux it is the heart of the system. It is rare that you use the CMD windows during normal operation in Windows, but once you are up to speed with Linux it will become second nature.

The Shell is also referred to as Bash (Bourne Again Shell) in Debian, but there are other versions of it around. The Shell is a command line interpreter, meaning it takes your command, turns it into Linux speak, processes the command, then produce the result.
To start the shell you can use the Terminal menu option from the GUI menu in Debian. You should then see a window much like the one above although it may be a different color.

You will see one of two prompts. A $ which is the general user prompt, or a # for the root user. I would hope that especially during your first weeks with Linux you will be logging in as a general user and only using root when you need to.
The following are some basic commands to get you used to navigating the system. None of them will hurt anything, especially if you are in user mode. Note you don’t have to type the $.

$ pwd                  Will tell you what directory you are in.
$ cd                      Takes you to your home directory.
$ ls                        Lists the contents of your current directory
$ ls –l                   Displays the contents of the current directory in long format
$ ls –al                  Will show the long version of the directory including any hidden files
$ mkdir ‘name’     Will create a directory where ‘name’ is what you call it
$ rm ‘filename’     Deletes the file
$ rm –r ‘dirname’      Deletes the directory
$ cp file1 file2       Makes a copy of file1 and calls it file2
$ cp –r dir1 dir2     Makes a copy of directory1 and calls it dir2
$ mv file1 file2       This will move file one to file2
$ touch ‘filename’      Updates the file
$ more ‘filename’     Displays the contents of the file
$ head ‘filename’      Displays the first ten lines of the file
$ tail ‘filename’    Displays the last ten lines
Those are some of the basic file commands you can use to navigate and manipulate your files. How about a few command that give you information about your current machine and configuration?
$ date        Shows the current date
$ cal       Brings up the system calendar
$ uptime     Shows how long your system has been up. Useful for servers
$ df    Displays your disk usage
$ du   Displays your directory space usage
$ free   Displays your memory and swap file usage, again useful for servers
The shell is a massive subject, and one you should become familiar with over time. It is an extremely useful and powerful tool once you get the hang of it. Despite not being as pretty and as interactive as using the GUI, it seems to get things done quicker and in a no-nonsense kind of way.

Dual Booting Debian Lenny

If, like me you were a little dubious about your first forays into Linux, then dual booting is an option I would suggest. I wanted to try Debian, but wasn’t confident enough to leave my precious XP behind completely. I decided to go down the dual booting route, and although it may sound complicated it actually isn’t.
You will need to back up all your important stuff before doing anything, as we need to set up a partition in your hard disk to install into. Then download a freeware program called Easeus.
First thing you need to do is boot into XP and start Easeus. What you will see here is a graphical representation of your system drives. Choose the hard drive you want to install Linux on and resize it. You can either click on the relevant disk and choose the resize option at the top, or drag the slider on the disk pane. Ensure it is set as a Primary disk and you don’t have to worry about formatting it, just give it a drive letter and a name if you so desire. I called mine Debian so I would recognize it when I came to install it.

Once you have what you want, click Apply. Your system will reboot a couple of times while the changes are made, then it will boot into XP.
Now when you open up Easeus again you should see the changes that you made. The disk may appear as blank or empty if you decided not to format it, don’t worry about that as it will be formatted very soon!
Insert the Debian CD and set your machine up to boot from it. This is generally done from the Bios when the PC first starts. Depending on your PC it may be called something like Boot Options.
Boot into the Debian setup and follow the installation instructions. Make sure you choose the correct partition otherwise you might write over important files!
The install process is fairly straightforward, and the default settings should be sufficient for a new user. The install takes around thirty minutes, depending on your hardware and you are asked for input during the process, so don’t go anywhere!
The first time you reboot you should see the Grub boot loader screen with your options on it. At least one of them should be Debian and another Windows XP. You will get this option each time you boot your machine.
This can become a pain if you tend to turn on your PC and let it boot while you do something else like I used to.  GRUB, quite rightly, automatically selects Debian as the operating system to load, so if you want to boot into your old Windows install, you need to hang around for a few seconds to tell it to.

Distro Choice: Based on Using runlevels

Understanding Runlevels

After spending years on Redhat/CentOS versions of Linux which use runlevel 3 for text mode and runlevel 5 for graphical mode, and then after spending several years with Ubuntu which is moving away from runlevels and using Upstart, I was somewhat surprised with Debian Lenny which uses runlevels 2-5 as the same runlevel.  As a result I decided to review why Debian made this choice and if there are advantages to the runlevel changes.

What runlevels are.
The term runlevel stands for the mode that the operating system will operate in  For example, in RedHat based systems, use runlevel 3 in which the mode of operation is completely text based while runlevel 5 uses the graphical interface.  Two completely different modes of operation will be experienced by moving from runlevel 3 to 5.  This system is part of the Unix System V-style initialization.  Typically there have been 7 runlevels, 0-6, but in reality there are 10 but they are not all used currently.

Runlevel Modes

0     shut down
1     single user – system rescue
2     multi-user with no network
3     multiuser in text mode
4     not used
5     multi-user GUI mode
6     reboot

If you check around with multiple Linux systems you will see there are a number of distributions that have modified the runlevels and how they function including Debian.

How runlevels work
Typically during the boot process, once the kernel turns control over to init, init the default runelevel based on /etc/inittab.  This then sets the default runlevel and  calls the script at /etc/rc.d/rc.sysinit which starts many of the necessary system tasks such as kernel parameters from /etc/sysctl.conf, system clock, keymaps, swap, hostname,  executes root file system checks and then mounts it r/w, activates RAID, starts quotas, mounts file systems in /etc/fstab and then cleans up the PIDs and state locks that were set.  This is where the runlevels begin to make some changes to the operating system.  Each runlevel determines which daemons will run in that specific runlevel.  If you look in /etc/ you will see that there are directories that coincide with the runlevel.

/etc/rc0.d        Run level 0
/etc/rc1.d        Run level 1
/etc/rc2.d        Run level 2
/etc/rc3.d        Run level 3
/etc/rc4.d        Run level 4
/etc/rc5.d        Run level 5
/etc/rc6.d        Run level 6

These directories contain symbolic links to daemons so that when you start your system in a specific runlevel it will start those daemons that are supposed to be available in that runlevel.  Notice in this example that you have links that start with “K” and some with “S”.  This will determine which daemons are turned off in that runlevel “K”, for kill and those daemons which are started, “S”.

lrwxrwxrwx   1 root root   19 Dec 17 08:34 K05saslauthd -> ../init.d/saslauthd
lrwxrwxrwx   1 root root   19 Dec 17 08:35 K10dc_server -> ../init.d/dc_server
lrwxrwxrwx   1 root root   16 Dec 17 08:35 K10psacct -> ../init.d/psacct
lrwxrwxrwx   1 root root   19 Dec 17 08:35 K12dc_client -> ../init.d/dc_client
lrwxrwxrwx   1 root root   13 Dec 17 08:35 K20nfs -> ../init.d/nfs
lrwxrwxrwx   1 root root   14 Dec 17 08:35 K24irda -> ../init.d/irda
lrwxrwxrwx   1 root root   22 Dec 17 08:38 K30spamassassin -> ../init.d/spamassa ssin
lrwxrwxrwx   1 root root   19 Dec 17 08:37 K35vncserver -> ../init.d/vncserver
lrwxrwxrwx   1 root root   17 Dec 17 10:41 K35winbind -> ../init.d/winbind
lrwxrwxrwx   1 root root   14 Dec 17 09:17 K36lisa -> ../init.d/lisa
— cut —
lrwxrwxrwx   1 root root   23 Dec 17 08:35 S00microcode_ctl -> ../init.d/microco de_ctl
lrwxrwxrwx   1 root root   15 Dec 17 08:34 S05kudzu -> ../init.d/kudzu
lrwxrwxrwx   1 root root   18 Dec 17 08:35 S06cpuspeed -> ../init.d/cpuspeed
lrwxrwxrwx   1 root root   18 Dec 17 08:35 S08iptables -> ../init.d/iptables
lrwxrwxrwx   1 root root   14 Dec 17 08:35 S09isdn -> ../init.d/isdn
lrwxrwxrwx   1 root root   16 Dec 17 08:35 S09pcmcia -> ../init.d/pcmcia
lrwxrwxrwx   1 root root   17 Dec 17 08:34 S10network -> ../init.d/network
lrwxrwxrwx   1 root root   16 Dec 17 08:34 S12syslog -> ../init.d/syslog
lrwxrwxrwx   1 root root   20 Dec 17 08:35 S13irqbalance -> ../init.d/irqbalance
lrwxrwxrwx   1 root root   17 Dec 17 08:35 S13portmap -> ../init.d/portmap
lrwxrwxrwx   1 root root   17 Dec 17 08:35 S14nfslock -> ../init.d/nfslock

The significance of runlevels is the determination of which daemons are available when the system boots.  This is important in terms of resources used and in terms of security because many of these daemons will listen on ports for connections from the network when they are activated.

The files in the rcX.d directories are designed for the operating system to read.  Each file is a symbolic link to a script in the /etc/init.d directory and controls the starting, or stopping of a daemon or service.  The links start with the “K” or “S” and then are followed by a two digit number which determines the order in which they start or are turned off.  The string at the end is simply to help you understand what the link is to, human readable.

Debian Lenny
Debian uses the same runlevel settings for runlevels 2-5, in other words they do not make any distinction between a runlevel three typically used as a text mode or a runlevel 5 used as a GUI, graphical interface, mode.  The default is runlevel 2.

Here is a look at the contents of /etc/rc2.d
README        S12dbus         S20acct    S20nfs-common      S20xend     S26network-manager        S89anacron    S99rc.local
S05loadcpufreq    S14avahi-daemon  S20cups    S20openbsd-inetd  S21xendomains  S26network-manager-dispatcher    S89atd          S99rmnologin
S10rsyslog    S16ssh         S20exim4    S20postfix      S24dhcdbd     S30gdm                S89cron       S99stop-bootlogd
S12acpid    S19cpufrequtils  S20kerneloops    S20rsync      S24hal     S30system-tools-backends    S99bootchart

Note yours will look different depending upon what daemons you have installed.

If you wanted to boot your Debian Lenny version into text mode instead of the graphical mode, them you can either change the “S30gdm” to “s30gdm” or run this command:

mv /etc/rc2.d/S30gdm /etc/rc2.d/K70gdm

The system will ignore any lines that start with a lower case letter, to that is why the first example is successful.  The second example moves it from a (S)tart to a (K)ill effectively turning of the graphical mode.  Also note you may be using kdm or xdm instead of gdm.

Summary:
When you are making a choice on a Linux distribution to use, you aspect you may consider is. does the operating system make it easy for me to start in either grpahical mode or text mode.  RedHat/CentOS versions certainly make that an easy option by using the command:

init 3
or
init 5

The init command will allow you to move back and forth between runlevels.

In Debian, you do not have that option.  Debian runlevels are all the same in 2-5 so the only way to boot into text mode to to make a change to the /etc/rc2.d file for gdm as explained above.

Performing Backups in Linux

Linux may well be one of the most stable and reliable operating systems out there, but you should still plan for failure. Linux still depends on PC hardware and a steady power supply to be able to function properly. If you are administering Linux servers then this would be a no brainer, but even desktop users should bear it in mind. After messing up my first couple of installs it was something I quickly learned once I was up and running again. There’s nothing more frustrating than spending a couple of hours getting things just the way you like them to lose it all when you mess up!
There are three viable backup types for the home user.
The Full Backup. This does exactly what it says. It takes a full backup of everything, ready to restore if the worst happens. Although the most thorough, it also needs the most storage space.
Incremental Backup. This only backs up files that have been changed since the last time. This still needs a lot of storage space but once the initial copy is complete, subsequent copies are much quicker to manage.
Disk Mirroring. This makes an actual copy of the disk and puts it onto another physical drive. This is a bit extreme for a home user unless you are running a webserver or something and don’t want the downtime.
What you back up to dictates what you back up. Ideally you would back up everything, but not everyone has DVD burners, RAID arrays or spare hard disks lying around. As a rule of thumb, back up everything that a full reinstall of Debian wouldn’t replace.
If you don’t want or don’t have the resources to do a full backup, then I would suggest at the very least backing up /home and /etc. Your /home directory is where the user account data is stored.  Very handy to have a copy of this if you need to reinstall. The /etc directory is where the software configuration files are stored. Having a copy of this will save you hours if the worst happens. You should also consider backing up your /var directory as it contains the data for most of your data driven programs, like any databases you may have.
The easiest method of backup for the Debian newbie is KBackup. It has a nice graphical interface and walks you along the process. It also has a schedule setting so you can leave it to do its thing when you’re not around. You can install it from Synaptic and it is a doddle to set up. Just open the program and follow the onscreen instructions. You make a few choices and everything is taken care of for you.

Tar can also be used to back up your system if you choose to. You may know Tar already from having installed packages onto your system. Backing everything up in Tar is very simple.
tar cvf /dev/device   Where /device is your backup medium of choice.
To restore your home folder for instance use:
tar xvf  /dev/device /home   Again, where /device is your medium of choice.