“Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks.”
wikipedia.org
Category Archives: computing
Free your documents
“Start using ODF today. It’s the office document format of the future.”
youtube.com
Switching office suites from Microsoft Office to OpenOffice.org
“Think of this as a virtual guide, the written version of me coming over to your house on a Sunday afternoon to help get to know OpenOffice.org and figure out all the things you’re not quite sure about.” Solveig Haugland offers a virtual hand to hold.
www.fanaticattack.com
Norway mandates open formats
“In a move to ensure equal access to public information for Norwegian citizens, the government has decided to make the freely accessible document standards HTML, PDF, and ODF obligatory.” Justin Fielding reports on Norway joining countries such as the Netherlands, Belgium, Malaysia, Finland, France, Japan and Germany in a drive to make government documents more accessible.
techrepublic.com.com
Unified home networks with the FRITZ!Box
“The FRITZ!Box offers you freedom of choice. You can use your own FRITZ!Box with any operator and fine-tune your home network to your needs.” Guylhem Aznar shares his experience.
www.linuxdevcenter.com
Installing VMware tools for a Ubuntu guest
VMware Tools is a suite of utilities that enhances the performance of a virtual machine’s guest operating system.
Begin by setting up a new virtual machine and installing Ubuntu 6.06 LTS as the guest operating system. Start the virtual machine and log in as a user belonging to the admin group. You are now ready to install VMware Tools.
Get the necessary packages with the following command:
user@ubuntu:~$ sudo apt-get install build-essential linux-headers-`uname -r`
Become root and create a symbolic link with the following commands:
user@ubuntu:~$ sudo su
root@ubuntu:/home/user# ln -s /usr/src/linux-headers-`uname -r` /usr/src/linux
On the host, select Virtual Machine > Install VMware Tools… from the VMware Workstation menu.
After the guest has mounted the VMware Tools installation virtual CD, change the active directory and copy the VMware Tools archive with the following commands:
root@ubuntu:/home/user# cd /root/
root@ubuntu:~# cp /media/cdrom/VMwareTools-7.6.3-87978.tar.gz /root/
Extract the contents of the archive and then change the active directory with the following commands:
root@ubuntu:~# tar -zxvf VMwareTools-7.6.3-87978.tar.gz
root@ubuntu:~# cd vmware-tools-distrib/
Invoke the install script with the following command, choose to install the binary files in /usr/local/bin and and set your desired screen resolution:
root@ubuntu:~/vmware-tools-distrib# ./vmware-install.pl
Restart your virtual machine.
Analysis of Microsoft’s suicide note
“If Windows XP was Microsoft’s attempt to embed a browser into the operating system then Vista is the attempt to embed Digital Rights Management.” Oliver Day worries that Windows Vista is of real benefit only to content producers, not consumers.
badvista.fsf.org
Time synchronisation with NTP
The NTP protocol allows you to synchronise the clock of your computer with that of dedicated time servers on the Internet.
Get the necessary packages with the following command:
user@ubuntu:~$ sudo apt-get install ntp-simple ntpdate
Stop the ntpd daemon and manually synchronise your computer’s clock with the following two commands:
user@ubuntu:~$ sudo /etc/init.d/ntp-server stop
user@ubuntu:~$ sudo ntpdate pool.ntp.org
Modify the file /etc/ntp.conf to read:
# You do need to talk to an NTP server or two (or three).
#server ntp.your-provider.example
#server ntp.ubuntu.com
server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
Start the ntpd daemon with the following command:
user@ubuntu:~$ sudo /etc/init.d/ntp-server start
After about one minute, query the status of the ntpq daemon with the following command:
user@ubuntu:~$ sudo ntpq -p
You can further increase the accuracy of time synchronisation by using the time servers in your continental or country zone.
Sharing a PostScript printer with CUPS and Samba
Using Samba and CUPS, the Common UNIX Printing System, Ubuntu can easily be configured to provide printing services to a heterogeneous network of Windows, Macintosh and Linux clients.
Printing with CUPS
Get the necessary packages with the following command:
user@ubuntu:~$ sudo apt-get install cupsys foomatic-filters-ppds
Add the user cupsys to the group shadow:
user@ubuntu:~$ sudo adduser cupsys shadow
Get the file cupsd.conf and move it to /etc/cups/:
user@ubuntu:~# sudo wget "http://edafe.org/ubuntu/cups/cupsd.conf"
user@ubuntu:~# sudo mv cupsd.conf /etc/cups/
The downloaded file contains the following changes from the Ubuntu default configuration:
# Default authentication type, when authentication is required...
DefaultEncryption IfRequested
# Restrict access to the admin pages...
<Location /admin>
Allow @LOCAL
</Location>
Setting these options enables members of the admin group to modify the configuration of the CUPS server from clients sharing the same local network.
Modify the file /etc/cups/cups.d/ports.conf to read:
Port 631
Listen localhost
Listen 192.168.0.123
Listen /var/run/cups/cups.sock
For 192.168.0.123, substitute the IP address of your machine on the local network.
Restart cupsd with the following command:
user@ubuntu:~$ sudo /etc/init.d/cupsys restart
Use a web browser to access http://localhost:631/admin (or http://192.168.0.123:631/admin from another machine on your local network). Go to Administration > Add Printer and begin to set up your printer. When prompted by the system, authenticate yourself as a member of the admin group. If necessary, obtain the correct PostScript Printer Description (PPD) file for your printer model. Print a test page to confirm that your printer is working properly with CUPS.
Making Printers Available over the Network
Install and configure a Samba server and then add the following options to /etc/samba/smb.conf:
[global]
printing = cups
load printers = Yes
printcap name = cups
[printers]
comment = All Printers
printable = Yes
path = /var/spool/samba/print
browseable = No
guest ok = Yes
read only = Yes
Create the directory /var/spool/samba/print and set its permissions with the following two commands:
user@ubuntu:~$ sudo mkdir -p /var/spool/samba/print
user@ubuntu:~$ sudo chmod 1777 /var/spool/samba/print
Restart the Samba server with the following command:
user@ubuntu:~$ sudo /etc/init.d/samba restart
Set your Samba clients to use a printer driver that outputs generic PostScript. Use the the Apple LaserWriter driver on Windows, the Generic PostScript driver on Mac OS X or the Raw Standard driver on Ubuntu.
wiki.ubuntuusers.de, www.samba.org
Monitoring hard disks with smartmontools
This post has been updated.
Allowing other users to run sudo
user@ubuntu:~$ sudo adduser username admin
Editing configuration files with nano
There are many different tools that you can use to edit configuration files. Because of its simplicity, I personally like to use Nano:
user@ubuntu:~$ sudo nano /path/to/the/file
You can change the default settings for nano by editing its configuration file. For example, to stop nano from wrapping text simply make the following changes to /etc/nanorc:
## Don't wrap text at all.
set nowrap
Creating a software RAID-1 array
RAID stands for Redundant Array of Inexpensive Disks and refers to the use of multiple hard disks to share or replicate data between drives.
For RAID-1, you need two partitions of identical size on two separate disks which are not connected to the same IDE/Parallel ATA-bus.
Use cfdisk to create the two partitions /dev/hdb1 and /dev/hdc1. Set their respective types to FD and do not set their bootable flags. Create the RAID-1 array with the following command:
user@ubuntu:~$ sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/hd[bc]1
Create a filesystem on the RAID device with the following command:
user@ubuntu:~$ sudo mke2fs -j /dev/md0
Create an empty directory /raid as a mount point and add the following line to /etc/fstab:
/dev/md0 /raid ext3 defaults 0 2
Mount your RAID array and check its status with the following commands:
user@ubuntu:~$ sudo mount /raid
user@ubuntu:~$ sudo mdadm --detail /dev/md0
Monitoring the RAID Array
If required, start by configuring Postfix to redirect mail for the local root user.
Obtain the UUID of your RAID device with the following command:
user@ubuntu:~$ sudo mdadm -D /dev/md0
Create the file /etc/mdadm/mdadm.conf and add the following three lines, replacing 47d1eee2:2cbfr68v:34×75168:142ef912 with the UUID of your RAID:
DEVICE /dev/hdb1 /dev/hdc1
ARRAY /dev/md0 level=raid1 num-devices=2 UUID=47d1eee2:2cbfr68v:34x75168:142ef912
MAILADDR root
Edit the file /etc/init.d/mdadm and append –test to the line beginning with start-stop-daemon -S:
start-stop-daemon -S -q -p $PIDFILE -x $MDADM -- -F -i $PIDFILE -m $MAIL_TO -f -s --test
Restart the mdadm daemon with the following command:
user@ubuntu:~$ sudo /etc/init.d/mdadm restart
Verify that the local root user has received a test message from the mdadm daemon.
From now on, the mdadm daemon will monitor the integrity of the RAID array and, in the event of any problems, alert the local root user by email.
users.piuha.net/martti, www.tldp.net
Configuring a static IP address
Edit the file /etc/network/interfaces to contain the following entries:
# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.0.20
netmask 255.255.255.0
broadcast 192.168.0.255
gateway 192.168.0.1
Reconfigure the network interfaces with the following command:
user@ubuntu:~$ sudo /etc/init.d/networking restart
Enabling the root account
Consider the implications of enabling the root account, and then proceed with:
user@ubuntu:~$ sudo passwd root
To disable the root account again, use the following command:
user@ubuntu:~$ sudo passwd -l root
Samba as a file server
Samba enables Linux to speak the Server Message Block (SMB) protocol, which is also used by Windows and Mac OS X to exchange data over a network.
Get the necessary packages with the following command:
user@ubuntu:~$ sudo apt-get install swat netkit-inetd
For an initial configuration, edit the file /etc/samba/smb.conf to contain the following entries:
[global]
workgroup = SAMBA
[homes]
comment = Home Directories
valid users = %S
read only = No
create mask = 0640
directory mask = 0750
browseable = No
Continue by adding local users to the smbpasswd file:
user@ubuntu:~$ sudo smbpasswd -a user
Restart the Samba server with the following command:
user@ubuntu:~$ sudo /etc/init.d/samba restart
The server ubuntu now joins the SAMBA workgroup, giving users who have been added to the smbpasswd file access to their respective home directories.
Using SWAT
Using the Samba Web Administration Tool (SWAT), you can access help, obtain status information and change the configuration of your Samba server. Use a web browser to access http://localhost:901/ and log in as the local root user.
In principle, SWAT can also be reached from other machines on your local network. However, such connections are vulnerable to password sniffing because of the clear text protocol that SWAT uses to authenticate users.
www.samba.org, copia.ogbuji.net
A brief look at Slackware 11.0
“Slackware is one of the oldest Linux distributions out there. And over the years, it has consistently kept pace with the changes.”
linuxhelp.blogspot.com
Changing default permissions
Change the default permissions for your installation by editing the value for umask in /etc/profiles and /etc/login.defs.
lists.ubuntu.com
Setting the time zone
Set the local time zone with the following command:
user@ubuntu:~$ sudo tzconfig
Redirecting mail for the local root user
This post has been updated.