Linux server tutorials

How to copy a long file name from thumb drive?

2009-11-05T16:37:00.000-08:00

When copying files and directories from thumb drive or usb drive, we always dealing with windows file. There is no problem if you are using Ubuntu desktop because you just right-click the file, copy and paste it in your Linux. In Ubuntu server we are working in the command line terminal. To copy a long file name with white space need some creativity.

Here are some tips on how to copy longer file name with white space from thumb drive/usb drive in Linux command line terminal:

We need to add a backslash at the end of every words in the file name. Here is an example on how to copy longer file with white space:

kucing@ubuntu-server:/media/disk$ ls | grep Linux

Linux copy command tutorial.txt

Linux copy windows file.txt

Linux command copy file example01.txt

Type cp and the first word in the file name:

 kucing@ubuntu-server:/media/disk$ cp Linux

Pressing the tab key wouldn't help here. What you have to do is to put a backslash after the first word:

kucing@ubuntu-server:/media/disk$ cp Linux\

Press spacebar to put a white space and key in the second word:

kucing@ubuntu-server:/media/disk$ cp Linux\ copy\

Repeat steps above if you have a long file name.

kucing@ubuntu-server:/media/disk$ cp Linux\ copy\ windows\ file.txt /home/tutorials/

That's it. A simple thing but can cause a headache for a Linux beginner.

Add another admin in Ubuntu server

2009-08-05T20:25:00.000-07:00

There are several reasons why we need extra admin user in Ubuntu server. One of the reason perhaps it's an account for your boss. Yes, in several occasions, your boss needs root privilege to do whatever 'his job' that need to be done.

Well, whatever your reason is, here is how you can add another user in the admin group in Ubuntu server:

Login into Ubuntu server using user in admin group username(user with root privilege). This is the user that can use 'sudo' command, or the default user you created during Ubuntu server installation.

In the command prompt, type:


luzar@ubuntu:~$ sudo adduser jimi admin
Adding user `jimi' to group `admin' ...
Adding user jimi to group admin
Done.
luzar@ubuntu:~$

Replace jimi with a username that you want to add to the admin group. Let's check the /etc/group file to see whether the user has been added to the admin group:


luzar@ubuntu:~$ cat /etc/group

Here is the result:


luzar:x:1000:
lpadmin:x:112:
sambashare:x:113:
admin:x:114:luzar,jimi
programmer:x:1001:luzar
dhcpd:x:115:
jimi:x:1002:

That's it. Now jimi can run whatever commands that needs root privilege by using sudo command. He has the same power as you now.

How to check Ubuntu server Linux version

2009-06-24T01:55:00.000-07:00

If you are a Windows user before, there is no ver command in Linux that can be used to check the version of Ubuntu server. In Linux or Ubuntu server specifically, there are many commands that can be used to check operating system version.

The first command that can be used to check Ubuntu server version is, as Ubuntu suggest, the lsb_release -a command. Here is the example:

luzar@ubuntu:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 8.10
Release:        8.10
Codename:       intrepid
luzar@ubuntu:~$

Second command that we can use to check Linux version is cat /proc/version. See example below:

luzar@ubuntu:~$ cat /proc/version
Linux version 2.6.27-14-server (buildd@palmer) (gcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu12) ) #1 SMP Wed Apr 15 19:44:38 UTC 2009
luzar@ubuntu:~$

We can also view all information about Ubuntu server using uname -a option:

luzar@ubuntu:~$ uname -a
Linux ubuntu 2.6.27-14-server #1 SMP Wed Apr 15 19:44:38 UTC 2009 i686 GNU/Linux

There you go. We've got more information than what we ask for. Well, that's good, isn't it?

How to add user to a group in Linux operating system

2009-06-17T07:40:00.000-07:00

We can assign user to a group during adding a new user account. But how do we add existing user to a group? This tutorial is a guide on how to add user to a new group. The right Linux command for the job is the usermod command.

This is some information about Linux usermod command from manual page:


NAME
       usermod - modify a user account

SYNOPSIS
       usermod [options] LOGIN

DESCRIPTION
       The usermod command modifies the system account files to reflect the
       changes that are specified on the command line.

As you can see, the Linux usermod command can be used to modify a user account. However in this tutorial, we'll only use usermod command to add user to a new group. For this example, we'll create a new group to practice. Use the groupadd command to create a new group:

luzar@ubuntu:~$ groupadd programmer
groupadd: unable to lock group file
luzar@ubuntu:~$ sudo groupadd programmer
[sudo] password for luzar:
luzar@ubuntu:~$

Don't forget to use sudo command in Ubuntu, else you'll get the groupadd: unable to lock group file error as in the example above. Check whether the programmer group has been created in /etc/group file:

luzar@ubuntu:~$ less /etc/group | grep programmer
programmer:x:1001:
luzar@ubuntu:~$

Next, we are going to add user to a new group. For this example, we are going to add a user called luzar to the programmer group. Below are step by step instructions.

Use usermod -G option to add user to a new group:

luzar@ubuntu:~# sudo usermod -G programmer luzar

Use Linux groups command to check whether the programmer group has been added to luzar's group:

luzar@ubuntu:~# groups luzar
luzar : users programmer
luzar@ubuntu:~#

As you can see, the user luzar now has programmer as a second group. We can also check /etc/group to verify user currently in the programmer group:

luzar@ubuntu:~$ less /etc/group | grep programmer
programmer:x:1001:luzar
luzar@ubuntu:~$

That's all.

How to mount external hard drive in Ubuntu server

2009-03-22T22:58:00.000-07:00

This is a step by step guide on how to mount external hard drive in Linux for Ubuntu server beginner and Linux beginner in general. The guide includes error happened during the process to show how it to mount device in real situation.

Mount external hard drive in Ubuntu server

Insert external hard drive usb connector into the Ubuntu server usb port. Ubuntu server automatically detect the external hard drive as a usb device. Below is the example screenshot when ubuntu detected the external hard drive:

We can see that the external hard drive has been detected as sdb. That is the name of the external hard drive to use when we are going to mount the device. We can check the device in /proc/scsi/scsi file. To do that, issue the command as in the example below:

luzar@ubuntu:~$ cat /proc/scsi/scsi
Attached devices:
Host: scsi1 Channel: 00 Id: 00 Lun: 00
Vendor: NECVMWar Model: VMware IDE CDR10 Rev: 1.00
Type:   CD-ROM                           ANSI SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
Vendor: VMware, Model: VMware Virtual S Rev: 1.0
Type:   Direct-Access                    ANSI SCSI revision: 02
Host: scsi3 Channel: 00 Id: 00 Lun: 00
Vendor: Generic Model: USB Disk         Rev: 9.02
Type:   Direct-Access                    ANSI SCSI revision: 02
luzar@ubuntu:~$

Create a proper directory in Ubuntu server to mount the external hard drive. In this example, we create a directory named extdisk in /mnt directory:

luzar@ubuntu:~$ sudo mkdir /mnt/extdisk
[sudo] password for luzar:
luzar@ubuntu:~$ ls /mnt/
dvd extdisk usb win

Now we can mount the external hard drive with Linux mount command:

luzar@ubuntu:~$ sudo mount /dev/sdb /mnt/extdisk/
mount: you must specify the filesystem type

The external hard drive cannot be mounted. This happened when we mount a windows formatted external hard drive. We must specify the filesystem. Windows filesystem format is known as nsfs-3g in Linux. So we mount the external hard drive again with the complete command:

luzar@ubuntu:~$ sudo mount -t ntfs-3g /dev/sdb /mnt/extdisk/
NTFS signature is missing.
Failed to mount '/dev/sdb': Invalid argument
The device '/dev/sdb' doesn't have a valid NTFS.
Maybe you selected the wrong device? Or the whole disk instead of a
partition (e.g. /dev/hda, not /dev/hda1)? Or the other way around?

We still cannot mount the external hard drive. Again, we mount the external hard drive but this we change the device name from /dev/sdb to /dev/sdb1 as suggested by Ubuntu message above.

luzar@ubuntu:~$ sudo mount -t ntfs-3g /dev/sdb1 /mnt/extdisk/
luzar@ubuntu:~$ ls /mnt/extdisk/
ghost dell170l ghost mimos RECYCLER System Volume Information
luzar@ubuntu:~$

We successfully mounted the external hard drive this time. Now that the external drive has been mounted, we can use it as other directory in Ubuntu.

To unmount the external hard drive, we can use the Linux umount command like in the example below:

luzar@ubuntu:~$ sudo umount /mnt/extdisk/
[sudo] password for luzar:
luzar@ubuntu:~$

That's all.

How to power off Ubuntu server with Linux shutdown command

2009-03-15T21:13:00.000-07:00

The Linux shutdown command has several options that you can use to bring down the Linux system. In the previous post, we've seen how to reboot Ubuntu server with shutdown command. In this post, we are going to use the Linux shutdown command again. This time is to power off the Ubuntu server.

There are several options available with shutdown command that can be used to power off Linux system. One example is -h option, which means to halt the system after it has been brought down. We can add other things such as a comment message when invoking shutdown -h command. As you can see from the example of Ubuntu restart post before, we have to specify a time argument after the shutdown option so the system know when to shutdown the system. Here are some examples on how to power off Ubuntu server using shutdown command with other things that you can do:

1) Using Linux shutdown command with -h option example:

luzar@ubuntu:~$ sudo shutdown -h now
[sudo] password for luzar:

Broadcast message from luzar@ubuntu
        (/dev/pts/0) at 11:32 ...

The system is going down for halt NOW!

The example above show a basic shutdown command used to power off Ubuntu server. We used '-h' option and a time argument 'now' which means to bring down the system after we press enter.

2) Using Linux shutdown command -p option example:

luzar@ubuntu:~$ sudo shutdown -h -P +1

Broadcast message from luzar@ubuntu
        (/dev/pts/0) at 11:47 ...

The system is going down for power off IN ONE MINUTE!

The example above shows the '-P' option is added after the '-h' option. The -P option means 'power off'. When -P is used after -h option, it means we tell the system to power off after the system halt. Also this time we used +1 in the time argument. That means we want to bring down the system after 1 minute.

3) If you have to warn all your users, you can write a message after the time argument. See the example below:

luzar@ubuntu:~$ sudo shutdown -h -P +3 Please save your work now!

Broadcast message from luzar@ubuntu
        (/dev/pts/0) at 11:57 ...

The system is going down for power off in 3 minutes!
Please save your work now!
shutdown: Shutdown cancelled

If you want to cancel shutdown after invoked the command, you can press Ctrl+C combination keys. That will work if you do not use the 'now' time argument. If you just want to warn users to log out and prevent other user to login without actually bring the system down, you can use '-k' option.

luzar@ubuntu:~$ sudo shutdown -k +3 Please save your work now!

Broadcast message from luzar@ubuntu
        (/dev/pts/0) at 12:11 ...

The system is going down for maintenance in 3 minutes!
Please save your work now!
luzar@ubuntu:~$

That's all.

Restart Ubuntu server

2009-03-03T00:52:00.000-08:00

There are many commands that can be used to restart Ubuntu Server. We are going to look at some of them that I remember. The first one is the reboot command. In Linux reboot means restart. To use the reboot command, invoke reboot at the command line terminal. You must have root privilege, so add sudo before reboot.

Restart Ubuntu server with reboot command example:

luzar@ubuntu:~$ sudo reboot
[sudo] password for luzar:

The second command that can be used to restart Ubuntu server is the shutdown command. In Ubuntu, you can use shutdown command to bring down the system to restart or to power off the system. That depends on the option given with shutdown command. To restart Ubuntu system with shutdown command, use shutdown with -r option and provide time to shutdown the system. See the example below.

Restart Ubuntu server with shutdown command example:

luzar@ubuntu:~$ sudo shutdown -r 18:00
[sudo] password for luzar:

Broadcast message from luzar@ubuntu
(/dev/pts/0) at 16:24 ...

The system is going down for reboot in 96 minutes!

Broadcast message from luzar@ubuntu
(/dev/pts/0) at 16:30 ...

The system is going down for reboot in 90 minutes!

Press Ctrl+c to cancel restart.

The system is going down for reboot in 90 minutes!
shutdown: Shutdown cancelled
luzar@ubuntu:~$

You can use shutdown command to restart the system on the spot using now as the time argument. See an example below:

luzar@ubuntu:~$ sudo shutdown -r now
[sudo] password for luzar:

Broadcast message from luzar@ubuntu
(/dev/pts/0) at 16:44 ...

The system is going down for reboot NOW!

That's the command that you can used to restart Ubuntu server system if you have to.

How to change hostname in Ubuntu server

2009-02-13T08:11:00.000-08:00

Change a hostname in Ubuntu server is very easy. From the command line terminal, type hostname newname. View the new hostname with hostname command. See the step by step example on how to change Ubuntu server hostname below:

1) View current hostname:


luzar@hitam:~$ hostname
hitam
luzar@hitam:~$

2) Change hostname and view latest hostname:


luzar@hitam:~$ sudo hostname ubuntu
luzar@hitam:~$ hostname
ubuntu
luzar@hitam:~$

See, that's how easy it is. Heh, don't fall for it. That doesn't change anything. The hostname is still the same as you can see at the prompt. Even reboot won't change anything. The exact method to change the hostname permanently is by editing /etc/hostname file. Here is the step:

1) Open /etc/hostname with your favorite text editor:


luzar@hitam:~$ sudo vim /etc/hostname
[sudo] password for luzar:

Here the vim /etc/hostname screenshot:

Now you can change hostname and save. The changed is permanent even after you reboot your system.

Ubuntu tail log tutorial

2009-02-10T17:50:00.000-08:00

Sometimes we need to view just a part of a big Ubuntu file. For example. when we are going to locate error or check system activity in Ubuntu system log. Ubuntu command that can be used to check for latest log generated by the system is tail command. The tail command by default displays last 10 lines in the file.

Here is part of tail manual page that describes the usage:

NAME
       tail - output the last part of files

SYNOPSIS
       tail [OPTION]... [FILE]...

DESCRIPTION
       Print  the  last 10 lines of each FILE to standard output.
       With more than one FILE, precede each with a header giving
       the file name.  With no FILE, or when FILE is -,
       read standard input.

If we are going to check latest system log, we can issue tail /var/log/messages command. See an example below:

luzar@ubuntu:/var/log$ tail /var/log/syslog
Feb 11 09:30:01 ubuntu console-kit-daemon[5150]: CRITICAL: 
cannot initialize libpolkit
Feb 11 09:30:01 ubuntu /USR/SBIN/CRON[5213]: (root) CMD ([ -x 
/usr/sbin/update-motd ] && /usr/sbin/update-motd 2>/dev/null)
Feb 11 09:32:12 ubuntu dhclient: DHCPREQUEST of 172.16.153.129 on eth0 
to 172.16.153.254 port 67
Feb 11 09:32:12 ubuntu dhclient: DHCPACK of 172.16.153.129 from 172.16.153.254
Feb 11 09:32:12 ubuntu dhclient: bound to 172.16.153.129 -- renewal in 899 seconds.
Feb 11 09:40:01 ubuntu console-kit-daemon[5260]: CRITICAL: 
cannot initialize libpolkit
Feb 11 09:40:01 ubuntu /USR/SBIN/CRON[5323]: (root) CMD ([ -x 
/usr/sbin/update-motd ] && /usr/sbin/update-motd 2>/dev/null)
Feb 11 09:47:11 ubuntu dhclient: DHCPREQUEST of 172.16.153.129 on eth0 
to 172.16.153.254 port 67
Feb 11 09:47:11 ubuntu dhclient: DHCPACK of 172.16.153.129 from 172.16.153.254
Feb 11 09:47:11 ubuntu dhclient: bound to 172.16.153.129 -- renewal in 883 seconds.
luzar@ubuntu:/var/log$

We can use tail to check latest messages generated by system log, we can issue tail /var/log/messages command. See an example below:

luzar@ubuntu:~$ tail /var/log/messages
Feb 11 09:06:04 ubuntu kernel: [    8.354312] lp0: using parport0 
(interrupt-driven).
Feb 11 09:06:04 ubuntu kernel: [    8.427308] Adding 489940k swap on /dev/sda5.
Priority:-1 extents:1 across:489940k
Feb 11 09:06:04 ubuntu kernel: [    8.462337] EXT3 FS on sda1, internal journal
Feb 11 09:06:04 ubuntu kernel: [    8.707586] ip_tables: (C) 2000-2006 
Netfilter Core Team
Feb 11 09:06:04 ubuntu kernel: [    8.746051] eth0: link up
Feb 11 09:06:04 ubuntu kernel: [   13.362431] NET: Registered protocol family 17
Feb 11 09:06:04 ubuntu kernel: [   20.601093] NET: Registered protocol family 10
Feb 11 09:06:04 ubuntu kernel: [   20.611324] lo: Disabled Privacy Extensions
Feb 11 09:26:09 ubuntu -- MARK --
Feb 11 09:46:09 ubuntu -- MARK --
luzar@ubuntu:~$

Remember that tail command is very useful command when troubleshooting error during Ubuntu server configuration.

Ubuntu w3m web browser tutorial

2009-02-01T04:37:00.001-08:00

Ubuntu server default web browser is w3m. You may already know that Ubuntu server didn't come with x-window, that means no gnome or kde. So as you have guess, w3m is a text-based web browser. And when I said w3m is a default Ubuntu web browser, that means it's already in the system when you finished installed Ubuntu server.
Other than being a web browser, w3m also capable of viewing a text file or a local html file. That means w3m can be a pager too such as less or more command. Let's look at w3m syntax.

Syntax:
usage: w3m [options] [URL or filename]

The options is optional. To view a webpage, you just type w3m www.website.com. Here is a screenshot example of a google search engine opened using w3m:

To quit w3m, press q:

Do you want to exit w3m? (y/n)

Answer n to quit w3m.
Below are options available to use with w3m. You can view w3m options with w3m -help command.

luzar@ubuntu:~$ w3m -help
w3m version w3m/0.5.2, options lang=en,m17n,image,color,ansi-color,mouse,gpm,menu,cookie,ssl,ssl-verify,
external-uri-loader,w3mmailer,nntp,gopher,ipv6,alarm,mark,migemo
usage: w3m [options] [URL or filename]
options:
    -t tab           set tab width
    -r               ignore backspace effect
    -l line          # of preserved line (default 10000)
    -I charset       document charset
    -O charset       display/output charset
    -B               load bookmark
    -bookmark file   specify bookmark file
    -T type          specify content-type
    -m               internet message mode
    -v               visual startup mode
    -M               monochrome display
    -N               open URL of command line on each new tab
    -F               automatically render frame
    -cols width      specify column width (used with -dump)
    -ppc count       specify the number of pixels per character (4.0...32.0)
    -ppl count       specify the number of pixels per line (4.0...64.0)
    -dump            dump formatted page into stdout
    -dump_head       dump response of HEAD request into stdout
    -dump_source     dump page source into stdout
    -dump_both       dump HEAD and source into stdout
    -dump_extra      dump HEAD, source, and extra information into stdout
    -post file       use POST method with file content
    -header string   insert string as a header
    +           goto  line
    -num             show line number
    -no-proxy        don't use proxy
    -4               IPv4 only (-o dns_order=4)
    -6               IPv6 only (-o dns_order=6)
    -no-mouse        don't use mouse
    -cookie          use cookie (-no-cookie: don't use cookie)
    -pauth user:pass proxy authentication
    -graph           use graphic character
    -no-graph        don't use graphic character
    -s               squeeze multiple blank lines
    -W               toggle wrap search mode
    -X               don't use termcap init/deinit
    -title[=TERM]    set buffer name to terminal title string
    -o opt=value     assign value to config option
    -show-option     print all config options
    -config file     specify config file
    -help            print this usage message
    -version         print w3m version
    -reqlog          write request logfile
    -debug           DO NOT USE
luzar@ubuntu:~$

Ubuntu scp command guide

2009-01-27T05:49:00.000-08:00

There are many methods available to copy files from Ubuntu server. The common method is file transfer protocol. You can see that in my previous post, Ubuntu ftp guides. Another way of copying files from Ubuntu server is using scp command. Let's see a brief information about scp from manual page:


NAME
     scp -- secure copy (remote file copy program)

SYNOPSIS
     scp [-1246BCpqrv] [-c cipher] [-F ssh_config] [-i identity_file]
         [-l limit] [-o ssh_option] [-P port] [-S program]
         [[user@]host1:]file1 ... [[user@]host2:]file2

DESCRIPTION
     scp copies files between hosts on a network.  It uses ssh(1) for data
     transfer, and uses the same authentication and provides the same security
     as ssh(1).  Unlike rcp(1), scp will ask for passwords or passphrases if
     they are needed for authentication.

     File names may contain a user and host specification to indicate that the
     file is to be copied to/from that host.  Local file names can be made
     explicit using absolute or relative pathnames to avoid scp treating file
     names containing ':' as host specifiers.  Copies between two remote hosts
     are also permitted.

As you can see from the manual page above, scp is a secure copy command uses ssh protocol to copy files from remote machine. We should know why it's called secure copy. It uses ssh protocol so it means data transferred is encrypted, and authentication is needed to copy the data.

Maybe it's easy for advanced Linux user to read and understand manual page. Can beginner understand the synopsis above and be able to use scp just by referring to the synopsis alone? Some can but mostly can't. So here's a simple scp format for most of you who can't read manual yet:

scp [options] [source_file] [destination_file]

scp [-r -p -v] [user@host:filename] [user@host:filename]

Here is an example of using scp command:


luzar@ubuntu:~$ scp luzar@192.168.1.6:/home/luzar/etc/UserManual.pdf .
luzar@192.168.1.6's password:
UserManual.pdf               100% 3812KB   3.7MB/s   00:00
luzar@ubuntu:~$

The example above demonstrate how to use scp to remotely copy a file. The target(remote server) is luzar@192.168.1.6 and the destination is our current directory (. means current directory). If you want to copy a folder, add -r option for the scp command.

Ubuntu server 8.10 installation - Scanning the mirror hangs

2008-12-20T02:54:00.000-08:00

I am a little surprise when Ubuntu 8.10 server installation seems like hangs in scanning the mirror during the installation step. It was more than 10 minutes I think and the installation screen just freezes like the picture below:

I wonder did I make a mistake during network configuration steps? No, I did the same steps a few times already including when I installed Ubuntu 8.04. Although there are slightly different steps in Ubuntu 8.10, but the configuration is just the same to me. I was not worry about the configuration, I know I set it up right. But the networking itself made me worry. The connection to the Internet has been bad for a few weeks already.

So I opened a web browser from windows to check the Internet connection, and I found it was ok. That means the installation should be ok. Maybe I should wait a little longer. I just leaved Ubuntu scanning the mirror and went take a bath. When I went back, I see the screen still scanning the mirror. Something must be wrong. It was the time when I tried to interrupt the installation, the screen moved.
That means the installation was ok. It just took some times to scan the mirror. I mean quite some times to scan the mirror. That never happened before. Then it stop again this time it scans the security updates repository:

I wasn't worry anymore. Take how much times you need, I know you were ok!

Ubuntu copy paste in command line terminal

2008-12-12T14:53:00.000-08:00

Sometimes we need to copy text from somewhere and paste it in Ubuntu command line for some reasons. For example, you are learning Linux bash shell scripting from the Internet. It is faster, easier and safer if you can copy an example bash script from the Internet and paste it in command line rather than typing it. How do you copy and paste text in Ubuntu command line? Here is how I do it.

Using cat command

This is one of the mostly used command in Linux, at least by me. The cat command normally used to read file but also can be used to append text to a file. We are going to use that append part to copy and paste text in command line terminal. Let's see an example:

This is a script from the Internet that I want to copy. So I highlight the text, right-click and choose copy.

Next, open Ubuntu command line terminal and using cat command to paste the text I copied earlier. Here is the steps:


luzar@ubuntu:~$ cat >> paste.txt
NameVirtualHost *
<VirtualHost * >
        ServerAdmin webmaster@localhost

        DocumentRoot /var/www/
        <Directory />
                Options FollowSymLinks
                AllowOverride None
        </Directory>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
        </Directory>
luzar@ubuntu:~$ ls -l | grep paste.txt
-rw-r--r-- 1 luzar luzar  432 2008-12-12 18:55 paste.txt
luzar@ubuntu:~$ cat paste.txt
NameVirtualHost *
<VirtualHost * >
        ServerAdmin webmaster@localhost

        DocumentRoot /var/www/
        <Directory />
                Options FollowSymLinks
                AllowOverride None
        </Directory>
        <Directory /var/www/>
                Options Indexes FollowSymLinks MultiViews
                AllowOverride None
                Order allow,deny
                allow from all
        </Directory>
luzar@ubuntu:~$

Here is explanation of the example above. The command cat >> paste.txt will append text(input) into a file name paste.txt. Press enter and you'll see no command prompt. That means cat is waiting for the input. So, right-click to paste the text we copied earlier. When we finished, press Ctrl+d to save and exit.

The ls -l | grep paste.txt and cat paste.txt just to show result of what we did.

That's all. Light and easy.

Ubuntu apache server installation

2008-12-10T19:57:00.000-08:00

This is a guide on how to install web server in Ubuntu. Ubuntu uses Apache as a web server. In this tutorial, user will learn how to check apache2 package in Ubuntu system before proceed to the apache2 installation itself. Apache2 web server can be installed from binary package or from source. The easiest method is installing apache2 web server from binary package using package management system.

Check apache server in Ubuntu

First, you have to check whether apache has been installed in your system or not. You can use any of the methods shown below:

Example using dpkg command to check apache in Ubuntu:

luzar@ubuntu:~$ sudo dpkg -l | grep apache
ii  apache2              2.2.8-1ubuntu0.3   Next generation, scalable, extendable web server
ii  apache2-mpm-prefork  2.2.8-1ubuntu0.3  Traditional model for Apache HTTPD
ii  apache2-utils        2.2.8-1ubuntu0.3  utility programs for webservers
ii  apache2.2-common     2.2.8-1ubuntu0.3  Next generation, scalable, extendable web server
ii  libapache2-mod-php5  5.2.4-2ubuntu5.4  server-side, HTML-embedded scripting language
luzar@ubuntu:~$

Example using ps command to check apache service in Ubuntu:

luzar@ubuntu:~$ ps aux | grep apache2
root      4594  0.0  1.3  20460  6748 ?  Ss  22:05  0:00 /usr/sbin/apache2 -k start
www-data  5247  0.0  0.6  20460  3376 ?  S   22:57  0:00 /usr/sbin/apache2 -k start
www-data  5248  0.0  0.6  20460  3376 ?  S   22:57  0:00 /usr/sbin/apache2 -k start
www-data  5249  0.0  0.6  20460  3376 ?  S   22:57  0:00 /usr/sbin/apache2 -k start
www-data  5253  0.0  0.6  20460  3376 ?  S   22:57  0:00 /usr/sbin/apache2 -k start
www-data  5255  0.0  0.6  20460  3376 ?  S   22:57  0:00 /usr/sbin/apache2 -k start
luzar     8448  0.0  0.1  3004   756 pts/0   R+   23:51   0:00 grep apache2
luzar@ubuntu:~$

Example using aptitude command to search apache package in Ubuntu:

luzar@ubuntu:~$ sudo aptitude search apache2
[sudo] password for luzar:
i   apache2                  - Next generation, scalable, extendable web
v   apache2-dev              -
p   apache2-doc              - documentation for apache2
v   apache2-mpm              -
p   apache2-mpm-event        - Event driven model for Apache HTTPD
p   apache2-mpm-itk          - multiuser MPM for Apache 2.2
p   apache2-mpm-perchild     - Transitional package - please remove
i   apache2-mpm-prefork      - Traditional model for Apache HTTPD
p   apache2-mpm-worker       - High speed threaded model for Apache HTTPD
p   apache2-prefork-dev      - development headers for apache2
p   apache2-src              - Apache source code
p   apache2-threaded-dev     - development headers for apache2
i   apache2-utils            - utility programs for webservers
i   apache2.2-common         - Next generation, scalable, extendable web
p   gforge-web-apache2       - collaborative development tool - web part
p   libapache2-authenntlm-perl  - Perform Microsoft NTLM and Basic User Auth
p   libapache2-mod-apparmor  - changehat AppArmor library as an Apache mo
p   libapache2-mod-apreq2    - generic Apache request library - Apache mo
p   libapache2-mod-auth-kerb    - apache2 module for Kerberos authentication
p   libapache2-mod-auth-mysql   - Apache 2 module for MySQL authentication
p   libapache2-mod-auth-openid  - OpenID authentication module for Apache2
p   libapache2-mod-auth-pam     - module for Apache2 which authenticate usin
p   libapache2-mod-auth-pgsql   - Module for Apache2 which provides pgsql au
p   libapache2-mod-auth-plain   - Module for Apache2 which provides plaintex
p   libapache2-mod-auth-radius  - Apache 2.x module for RADIUS authenticatio
p   libapache2-mod-auth-shadow    - Apache2 module for authentication using sh
p   libapache2-mod-auth-sys-group   - Module for Apache2 which checks user again
p   libapache2-mod-authnz-external  - authenticate Apache against external authe
p   libapache2-mod-bt           - BitTorrent tracker for the Apache2 web ser
p   libapache2-mod-bt-dev       - Header files for mod_bt
p   libapache2-mod-chroot       - run Apache in a secure chroot environment
p   libapache2-mod-defensible   - module for Apache2 which provides DNSBL us
p   libapache2-mod-dnssd        - Zeroconf support for Apache 2 via avahi
p   libapache2-mod-encoding     - Apache2 module for non-ascii filename inte
p   libapache2-mod-evasive      - evasive module to minimize HTTP DoS or bru
p   libapache2-mod-fastcgi      - Apache 2 FastCGI module for long-running C
p   libapache2-mod-fcgid        - an alternative module compat with mod_fast
p   libapache2-mod-geoip        - GeoIP support for apache2
p   libapache2-mod-jk           - Apache 2 connector for the Tomcat Java ser
p   libapache2-mod-layout       - Apache web page content wrapper
p   libapache2-mod-ldap-userdir  - Apache module that provides UserDir lookup
p   libapache2-mod-line-edit    - search-and-replace line editor module for
p   libapache2-mod-log-sql      - Use SQL to store/write your apache queries
p   libapache2-mod-log-sql-dbi   - Use SQL to store/write your apache queries
p   libapache2-mod-log-sql-mysql  - Use SQL to store/write your apache queries
p   libapache2-mod-log-sql-ssl    - Use SQL to store/write your apache queries
p   libapache2-mod-macro        - Create macros inside apache2 config files
p   libapache2-mod-mime-xattr   - Apache2 module to get MIME info from files
p   libapache2-mod-mono         - Apache module for running ASP.NET applicat
p   libapache2-mod-musicindex   - Browse, stream, download and search throug
p   libapache2-mod-neko         - Apache module for running server-side neko
p   libapache2-mod-perl2        - Integration of perl with the Apache2 web s
p   libapache2-mod-perl2-dev    - Integration of perl with the Apache2 web s
p   libapache2-mod-perl2-doc    - Integration of perl with the Apache2 web s
i   libapache2-mod-php5         - server-side, HTML-embedded scripting langu
p   libapache2-mod-proxy-html   - Apache2 filter module for HTML links rewri
p   libapache2-mod-python       - Apache 2 module that embeds Python within
p   libapache2-mod-python-doc   - Apache 2 module that embeds Python within
v   libapache2-mod-python2.5    -
p   libapache2-mod-random       - Create random ads, quotes and redirects
p   libapache2-mod-removeip     - Module to remove IP from apache2's logs
p   libapache2-mod-rpaf         - module for Apache2 which takes the last IP
p   libapache2-mod-ruby         - Embedding Ruby in the Apache2 web server
p   libapache2-mod-scgi         - Apache module implementing the SCGI protoc
p   libapache2-mod-shib         - Shibboleth implements the OASIS SAML v1.1
p   libapache2-mod-speedycgi    - apache2 module to speed up perl scripts by
p   libapache2-mod-suphp        - Apache2 module to run php scripts with the
p   libapache2-mod-vhost-hash-alias - Fast and efficient way to manage virtual h
p   libapache2-mod-vhost-ldap   - Apache 2 module for Virtual Hosting from L
p   libapache2-mod-wsgi         - Python WSGI adapter module for Apache
p   libapache2-mod-xmlrpc2      - XMLRPC Server module for Apache2 web serve
p   libapache2-modbt-perl       - Perl bindings for mod_bt
p   libapache2-modxslt          - XSLT processing module for Apache 2.0.x ba
p   libapache2-redirtoservname  - Apache 2 module to redirect users to the c
p   libapache2-request-perl     - generic Apache request library - Perl modu
p   libapache2-svn              - Subversion server modules for Apache
p   libapache2-webauth          - Apache 2 modules for WebAuth authenticatio
p   libapache2-webkdc           - Apache 2 modules for a WebAuth authenticat
p   php5-apache2-mod-bt         - PHP bindings for mod_bt
p   rt3.6-apache2               - Apache 2 specific files for request-tracke
p   torrus-apache2              - Universal front-end for Round-Robin Databa
luzar@ubuntu:~$

All the results above shown that apache is already installed in my system. If you didn't have apache yet, then you can install apache with a guide below.

Install apache server in Ubuntu

You can use any package management system in Ubuntu to install apache package. Ubuntu has two package management systems, apt and aptitude. However, apt is the most popular package management system and used by many system administrator. You can used any package management tool but it's recommended you stick with one that you are comfortable with.

Install apache package with apt-get command

Apt-get can be used to install, upgrade or remove package. This is an example of how to use apt-get command to install apache2 package:

sudo apt-get install apache2

Install apache package with aptitude command

Aptitude is the latest package management system developed for Debian. Ubuntu does not include aptitude in its official distribution. However, user can install aptitude using apt-get if they want aptitude in their system. Example using aptitude command to install apache2 package:

sudo aptitude install apache2

Ubuntu dhcp server setup

2008-11-30T05:20:00.000-08:00

In computer networking, there are two types of ip address configurations, dynamic ip address and static ip address. A dynamic ip address means, a host in a network doesn't have a specific ip address. A dhcp client host will ask it's ip address from a dhcp server, which provides ip address for all hosts in it's network.

DHCP is dynamic host configuration protocol. In Ubuntu, dhcp server package is called dhcp3-server. To setup dhcp server, you need to install the dhcp3-server software package and configure dhcpd.conf file, which is the dhcp server configuration file. In this post, I'll show you how I setup my Ubuntu dhcp server.

Install Ubuntu dhcp3-server with apt-get

There are many ways to install software packages in Ubuntu. Most people use apt-get, a command line package management. So, I'll show you how to install dhcp3-server using apt-get too.

Here is an example of installing Ubuntu dhcp3-server using apt-get:

luzar@ubuntu:~$ sudo apt-get install dhcp3-server
[sudo] password for luzar:Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer
 required:  libdns32 libisc32
Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:  dhcp3-server
0 upgraded, 1 newly installed, 0 to remove and 2 not upgraded.
Need to get 318kB of archives.
After this operation, 774kB of additional disk space will be used.
Get:1 http://us.archive.ubuntu.com hardy/main dhcp3-server
 3.0.6.dfsg-1ubuntu9 [318kB]
Fetched 318kB in 3s (106kB/s)
Preconfiguring packages ...
Selecting previously deselected package dhcp3-server.
(Reading database ... 28920 files and directories currently installed.)
Unpacking dhcp3-server
 (from .../dhcp3-server_3.0.6.dfsg-1ubuntu9_i386.deb) ...
Setting up dhcp3-server (3.0.6.dfsg-1ubuntu9) ...
Generating /etc/default/dhcp3-server...
 * Starting DHCP server dhcpd3                          [fail]
invoke-rc.d: initscript dhcp3-server, action "start" failed.
luzar@ubuntu:~$

The dhcp3-server installation is complete but fail to start the daemon. Don't worry, the dhcp3-server failed to start because we do not configure it yet. To configure the dhcp3-server, open /etc/dhcp3/dhcpd.conf file and read through a few times and you'll have a basic idea of how the configurations work.

We are going to edit the file, so make a copy of it first, as backup. Use cp command to copy the file:

luzar@ubuntu:~$ sudo cp /etc/dhcp3/dhcpd.conf
/etc/dhcp3/dhcpd.conf.bak
luzar@ubuntu:~$

Now you can edit /etc/dhcp3/dhcpd.conf to suit your network. Use any text editor you are comfortable with. Here is a tip before we begin editing. Do not remove unrelated configuration, just comment it. Maybe you'll need it later such as fixed ip host configuration. We'll use an existing configuration, change ip address regarding our network.

Here's an example of a simple dhcp configuration for a local network (in blue color):

luzar@ubuntu:~$ sudo less /etc/dhcp3/dhcpd.conf
#
# Sample configuration file for ISC dhcpd for Debian
#
# Attention: If /etc/ltsp/dhcpd.conf exists, that will be used as
# configuration file instead of this file.
#
# $Id: dhcpd.conf,v 1.1.1.1 2002/05/21 00:07:44 peloy Exp $
#


# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
ddns-update-style none;


# option definitions common to all supported networks...
# Change example.org to your domain name
# Change ns1 and ns2 to your host name
option domain-name "example.org";
option domain-name-servers ubuntu.example.org;


# Set default and max lease time. Time is in second.
default-lease-time 600;
max-lease-time 7200;


# If this DHCP server is the official DHCP server for the local
# network, the authoritative directive should be uncommented.
authoritative;


# Use this to send dhcp log messages to a different log file (you also
# have to hack syslog.conf to complete the redirection).
#log-facility local7;


# No service will be given on this subnet, but declaring it helps the
# DHCP server to understand the network topology.


#subnet 10.152.187.0 netmask 255.255.255.0 {
#}


# This is a very basic subnet declaration.
#subnet 10.254.239.0 netmask 255.255.255.224 {


#  range 10.254.239.10 10.254.239.20;
#  option routers rtr-239-0-1.example.org, rtr-239-0-2.example.org;
#}


# This declaration allows BOOTP clients to get dynamic addresses,
# which we don't really recommend.#subnet 10.254.239.32 netmask 255.255.255.224 {
#  range dynamic-bootp 10.254.239.40 10.254.239.60;


#  option broadcast-address 10.254.239.31;#  option routers rtr-239-32-1.example.org;
#}


# A slightly different configuration for an internal subnet.
#subnet 10.5.5.0 netmask 255.255.255.224 {
#  range 10.5.5.26 10.5.5.30;
#  option domain-name-servers ns1.internal.example.org;
#  option domain-name "internal.example.org";
#  option routers 10.5.5.1;
#  option broadcast-address 10.5.5.31;
#  default-lease-time 600;
#  max-lease-time 7200;
#}


# Here is my dhcp configuration for local network example
# I am not editing the example above instead I copy it here


subnet 192.168.1.0 netmask 255.255.255.0 {
  range 192.168.1.20 192.168.1.30;
  option domain-name-servers 192.168.44.128;
  option domain-name "ubuntu.example.org";
  option routers 192.168.44.128;
  option broadcast-address 192.168.44.254;
  default-lease-time 600;
  max-lease-time 7200;
}


# Hosts which require special configuration options can be listed in
# host statements. If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information


# will still come from the host declaration.
# Hosts which require special configuration options can be listed in
# host statements.   If no address is specified, the address will be
# allocated dynamically (if possible), but the host-specific information
# will still come from the host declaration.


#host passacaglia {
#  hardware ethernet 0:0:c0:5d:bd:95;
#  filename "vmunix.passacaglia";
#  server-name "toccata.fugue.com";
#}


# Fixed IP addresses can also be specified for hosts. These addresses
# should not also be listed as being available for dynamic assignment.
# Hosts for which fixed IP addresses have been specified can boot using
# BOOTP or DHCP. Hosts for which no fixed address is specified can only
# be booted with DHCP, unless there is an address range on the subnet
# to which a BOOTP client is connected which has the dynamic-bootp flag
# set.


#host fantasia {
#  hardware ethernet 08:00:07:26:c0:a5;
#  fixed-address fantasia.fugue.com;
#}


# You can declare a class of clients and then do address allocation
# based on that. The example below shows a case where all clients
# in a certain class get addresses on the 10.17.224/24 subnet, and all
# other clients get addresses on the 10.0.29/24 subnet.
#class "foo" {
#  match if substring (option vendor-class-identifier, 0, 4) = "SUNW";
#}


#shared-network 224-29 {
#  subnet 10.17.224.0 netmask 255.255.255.0 {
#    option routers rtr-224.example.org;
#  }
#  subnet 10.0.29.0 netmask 255.255.255.0 {
#    option routers rtr-29.example.org;
#  }
#  pool {
#    allow members of "foo";
#    range 10.17.224.10 10.17.224.250;
#  }
#  pool {
#    deny members of "foo";
#    range 10.0.29.10 10.0.29.230;
#  }
#}

Now we can restart the dhcp3-server again. You'll fail to start dhcp3-server if there's error in dhcp.conf file. You'll be prompt of what the error is. For example, here is an error I got when restarting my dhcp3-server:

luzar@ubuntu:~$ sudo /etc/init.d/dhcp3-server restart
dhcpd self-test failed. Please fix the config file.
The error was:
/etc/dhcp3/dhcpd.conf line 57: 2431504310 exceeds max (255) for precision.
  range 199999999926


/etc/dhcp3/dhcpd.conf line 57: too few numbers.
  range 199999999926 192.
Configuration file errors encountered -- exiting

So, I re-open dhcp.conf file and go to line 57 and fixed the error. You can also view /var/log/messages and /var/log/daemon.log to view error message. That's all that I need to do to configure dhcp in my local network.

Ubuntu search files using find command basic

2008-11-30T04:22:00.000-08:00

Basic find command

There are several ways to search files in Ubuntu. Probably you may already come across my other post about searching file in Ubuntu using locate command. Here is another way of searching files in Ubuntu. This time we are using the GNU find command. The find command comes with many options. That makes find a very powerful command. However, new users may not be very comfortable with find. I mean most users prefer a simple command, a command with less options to remember.

Don't ever think like that if you want to be a true Linux user. You must take advantage of powerful Linux command otherwise you would never see Linux full potential.

The manual page is a great help. Always make yourself a habit to read manual page for every new command. You don't have to read it all the first time you open it. My tip is, read the synopsis so you know the command's syntax. Then scan through some options. Some manual do have examples. Here are some informations about find in manual page:


NAME
     find - search for files in a directory hierarchy


SYNOPSIS
     find [-H] [-L] [-P] [path...] [expression]


DESCRIPTION
     This  manual page documents the GNU version of find.  GNU find searches
the directory tree rooted at each given file  name  by  evaluating  the
given  expression  from left to right, according to the rules of precedence
(see section OPERATORS), until the outcome  is  known  (the  left
hand  side  is  false  for and operations, true for or), at which point
find moves on to the next file name.


If you are using find in an environment where  security  is  important
(for example if you are using it to search directories that are writable
by other users), you should read the "Security Considerations"  chapter
of the findutils documentation, which is called Finding Files and comes
with findutils. That document also includes a  lot  more  detail  and
discussion  than  this  manual  page,  so you may find it a more useful
source of information.


EXPRESSIONS
     The expression is made up of  options  (which  affect  overall  operation
rather  than  the processing of a specific file, and always return true),
tests (which return a true or false value), and actions (which have  side
effects  and  return  a true or false value), all separated by operators.
-and is assumed where the operator is omitted.
If the expression contains no actions other than -prune, -print
is performed on all files for which the expression is true.

The meaning of synopsis options:

-H means do not follow symbolic links, except while processing the command line arguments.

-L means follow symbolic links.

-P means never follow symbolic links.

Let's try some examples to search file in Ubuntu using find command.

Example 1:

luzar@ubuntu:~$ find -P /home -iname File.txt
/home/luzar/File.txt
luzar@ubuntu:~$

In the example above, I used find command to search in /home directory for a file named file.txt. See that I used -iname instead of -name because -iname is case insensitive.

This concludes the basic find command guide. We'll continue advanced find command in another post.

Ubuntu nsswitch.conf guide

2008-11-30T04:17:00.000-08:00

Ubuntu nsswitch.conf is an important files regarding dns configuration. The nsswitch.conf is Name Service switch configuration file. Why does it important in dns configuration?

There are two important files in Ubuntu that directly deal with name server in mapping the host names and ip address. One is hosts file and the other is dns itself. This applied if you are not configuring NIS, of course. You can find these two files in nsswitch.conf configuration file. Open /etc/nsswitch.conf file using text editor or less command:

luzar@ubuntu:~$ sudo vi /etc/nsswitch.conf

Let's take a look at it more closely:


# /etc/nsswitch.conf
#
# Example configuration of GNU Name Service Switch functionality.
# If you have the `glibc-doc-reference' and `info' packages installed, try:
# `info libc "Name Service Switch"' for information about this file.


passwd:         compat
group:          compat
shadow:         compat


hosts:          files dns
networks:       files


protocols:      db files
services:       db files
ethers:         db files
rpc:            db files
netgroup:       nis~

Let's take a look at the line hosts which I already highlighted in blue. The hosts is pointing for files contain name server in the system when there is a request for it. As you can see, there are two files, files and dns. The files mention in hosts is a local file, which is the /etc/hosts file. The other file is dns, domain name server. The files will be check first and dns second. That means, /etc/hosts can override information in the dns configuration file.

Ubuntu dns server configuration

2008-11-30T03:56:00.000-08:00

Ubuntu dns server configuration involves many files. I would like to remind you again, please make a backup for every files before you begin editing. Example below:

luzar@ubuntu:/etc/bind$ sudo cp named.conf.local named.conf.local.bak
luzar@ubuntu:/etc/bind$ sudo cp named.conf.options named.conf.options.bak

The first file we are going to edit is the named.conf.local file. Use your favorite editor to open named.conf.local file.

luzar@ubuntu:/etc/bind$ sudo vim /etc/bind/named.conf.local

Type the code below. Replace example.com. with your domain name.


zone "example.com" in {
allow-transfer { any; };
file "/etc/bind/db.example.com.";
type master;
};


// Set up reversed name resolution
zone "1.168.192.in-addr.arpa" {
type master;
file "/etc/bind/db.192";
};

Example of /etc/bind/db.example.com configuration.


;
; BIND data file for local loopback interface
;
$TTL  604800
@   IN  SOA  ubuntu.example.com.  root.example.com. (
           2008112202           ; Serial
               604800           ; Refresh
                86400           ; Retry
              2419200           ; Expire
                86400 )         ; Negative Cache TTL
;

example.com   IN MX   mail.example.com.
@       IN NS           ubuntu.example.com.
@       IN A            192.168.1.3
ubuntu  IN A            192.168.1.3
web     IN CNAME        ubuntu.example.com.

Example of /etc/bind/db.192 configuration.


;
; Reverse lookup DNS Zone file
;
$TTL    604800
@   IN   SOA   ubuntu.example.com.  root.example.com. (
             2008112302         ; Serial
                 604800         ; Refresh
                  86400         ; Retry
                2419200         ; Expire
                  86400 )       ; Negative Cache TTL
@       IN NS           ubuntu.
3       IN CNAME        ubuntu.example.com.

You have to set the ISP dns server ip address. Put it in /etc/bind/named.conf.options forwarders:


        // If your ISP provided one or more IP addresses for stable
        // nameservers, you probably want to use them as forwarders.
        // Uncomment the following block, and insert the addresses replacing
        // the all-0's placeholder.


        forwarders {
        123.123.0.123;
        123.123.1.1;
        };

Example of /etc/resolv.conf configuration:

search example.comnameserver 192.168.1.3

Example of /etc/hosts configuration:


127.0.0.1       localhost
192.168.1.3     ubuntu.example.com      ubuntu

# The following lines are desirable for IPv6 capable hosts

::1     ip6-localhost ip6-loopbackfe00
::0 ip6-localnetff00
::0 ip6-mcastprefixff02
::1 ip6-allnodesff02
::2 ip6-allroutersff02
::3 ip6-allhosts

Restart bind9 service with the command below:

luzar@ubuntu:~$ sudo /etc/init.d/bind9 restart
 * Stopping domain name service... bind      [ OK ]
 * Starting domain name service... bind      [ OK ]

luzar@ubuntu:~$ tail /var/log/messages

Testing dns with dig domain name command:

luzar@ubuntu:/etc/bind$ dig example.com

; <<>> DiG 9.4.2-P2 <<>> example.com
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34700
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1,
ADDITIONAL: 1

;; QUESTION SECTION:;example.com.             IN      A


;; ANSWER SECTION:
example.com.        604800  IN  A    192.168.1.3


;; AUTHORITY SECTION:
example.com.        604800  IN  NS   ubuntu.example.com.


;; ADDITIONAL SECTION:
ubuntu.example.com. 604800  IN  A    192.168.1.3


;; Query time: 0 msec
;; SERVER: 192.168.1.3#53(192.168.1.3)
;; WHEN: Sun Nov 23 04:23:18 2008
;; MSG SIZE  rcvd: 82


luzar@ubuntu:/etc/bind$

Testing with dig ip address:

luzar@ubuntu:/etc/bind$ dig -x 192.168.1.3


; <<>> DiG 9.4.2-P2 <<>> -x 192.168.1.3
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 35746
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1,
ADDITIONAL: 0


;; QUESTION SECTION:
;3.1.168.192.in-addr.arpa.       IN  PTR


;; ANSWER SECTION:
3.1.168.192.in-addr.arpa. 604800 IN  CNAME  ubuntu.example.com.


;; AUTHORITY SECTION:
example.com.            86400   IN   SOA   ubuntu.example.com.
root.example.com. 2008112202 604800 86400 2419200 86400


;; Query time: 0 msec
;; SERVER: 192.168.1.3#53(192.168.1.3)
;; WHEN: Sun Nov 23 04:32:09 2008
;; MSG SIZE  rcvd: 115
luzar@ubuntu:/etc/bind$

If you have an error during configuration, please check error logs in:

/var/log/daemon.log.

/var/log/messages.

Here is an example of /var/log/daemon.log:

luzar@ubuntu:/etc/bind$ tail /var/log/daemon.log

Nov 24 10:23:05 ubuntu named[4554]: zone 28.172.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone 29.172.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone 30.172.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone 31.172.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone 168.192.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone 1.168.192.in-addr.arpa/IN:
 loaded serial 2008112302
Nov 24 10:23:05 ubuntu named[4554]: zone 255.in-addr.arpa/IN:
 loaded serial 1
Nov 24 10:23:05 ubuntu named[4554]: zone example.com/IN:
 loaded serial 2008112202
Nov 24 10:23:05 ubuntu named[4554]: zone localhost/IN:
 loaded serial 2
Nov 24 10:23:05 ubuntu named[4554]: running

Ubuntu named.conf

2008-11-30T03:48:00.000-08:00

Ubuntu named.conf file is the master configuration file for DNS server. Its pronounced name-dee for name daemon, which is the dns service. It's location is in /etc/bind/named.conf. You can find named.conf file only after you install the bind9 software package.

Here is an example of a default Ubuntu /etc/bind/named.conf configuration file:


// This is the primary configuration file for the BIND DNS server named.
//
// Please read /usr/share/doc/bind9/README.Debian.gz for information on the
// structure of BIND configuration files in Debian, *BEFORE* you customize
// this configuration file.
//
// If you are just adding zones, please do that in 
// include "/etc/bind/named.conf.local

include "/etc/bind/named.conf.options";
// prime the server with knowledge of the root servers

zone "." {
        type hint;
        file "/etc/bind/db.root";
};

// be authoritative for the localhost forward and reverse zones, and for
// broadcast zones as per RFC 1912

zone "localhost" {
        type master;
        file "/etc/bind/db.local";
};

zone "127.in-addr.arpa" {
        type master;
        file "/etc/bind/db.127";
};

zone "0.in-addr.arpa" {
        type master;
        file "/etc/bind/db.0";
};

zone "255.in-addr.arpa" {
        type master;
        file "/etc/bind/db.255";
};

include "/etc/bind/named.conf.local";

The named.conf is a very important file. Normally, you don't have to edit this file during dns configuration in Ubuntu. However, maybe you are going to open and view this file a few times to study it's configuration. It's a good idea to copy and make a backup of this file.

luzar@ubuntu:/etc/bind$ sudo cp named.conf named.conf.bak
[sudo] password for luzar:
luzar@ubuntu:/etc/bind$

As you can see, there are specific files in each zone in the named.conf configuration file above. Those are the database files for localhost and default dns configuration. We don't need to edit those files. You only need to edit two files mention at the top of named.conf which is /etc/bind/named.conf.local and /etc/bind/named.conf.options.

Ubuntu dns files

2008-11-30T03:43:00.000-08:00

DNS is domain name system. In Ubuntu, DNS package is included in bind9 software package. The dns server is called named. Basically what dns do, it translates name to ip address. It also translates ip address to name, which is called reverse dns.

Setting up dns involves several other files in Ubuntu system, the directly involved bind9 configuration files package and related files not in bind package. Here are all files needed to set up dns server, in bind package and not in bind package.

DNS configuration files in bind package:

luzar@ubuntu:~$ cd /etc/bind/
luzar@ubuntu:/etc/bind$ ls -l
total 44-rw-r--r-- 1 root root  237 2008-04-09 15:42 db.0
-rw-r--r-- 1 root root  271 2008-04-09 15:42 db.127
-rw-r--r-- 1 root root  237 2008-04-09 15:42 db.255
-rw-r--r-- 1 root root  353 2008-04-09 15:42 db.empty
-rw-r--r-- 1 root root  270 2008-04-09 15:42 db.local
-rw-r--r-- 1 root root 2878 2008-04-09 15:42 db.root
-rw-r--r-- 1 root bind  907 2008-04-09 15:42 named.conf
-rw-r--r-- 1 root bind  165 2008-04-09 15:42 named.conf.local
-rw-r--r-- 1 root bind  695 2008-04-09 15:42 named.conf.options
-rw-r----- 1 bind bind   77 2008-10-20 10:56 rndc.key
-rw-r--r-- 1 root root 1317 2008-04-09 15:42 zones.rfc1918
luzar@ubuntu:/etc/bind$

Related files not in bind package:

/etc/resolv.conf
/etc/hosts

/etc/nsswitch.conf

Here are screenshots of the files:

/etc/named.conf

/etc/named.conf is the main dns server configuration file. Here is a default content screenshot:

/etc/resolv.conf

/etc/resolv.conf is dns resolver file. Here is a default content screenshot:

/etc/bind/named.conf.local

/etc/bind/named.conf.local is a zone configuration file for dns setup. Here is a default content screenshot:

/etc/bind/named.conf.options

/etc/bind/named.conf.options file contains generic options for bind bind name server. Here is a default content screenshot:

Bind databases files

/etc/bind/db.root

/etc/bind/db.local

/etc/bind/db.0

/etc/bind/db.255

/etc/bind/db.127

/etc/bind/db.empty

Ubuntu install dns server

2008-11-30T03:28:00.000-08:00

Ubuntu uses named as its DNS or Internet domain name system server. Named is part of BIND 9 distribution from ISC. So, to install Ubuntu dns server, you must install bind software package. Luckily, there is no hassle installing software package in Ubuntu. There are more than one great package management system in Ubuntu that you can use.

Before we begin the bind9 installation, we better run apt-get update to resynchronize the package index files from the sources. So here we go:

luzar@ubuntu:~$ sudo apt-get update
[sudo] password for luzar:
Get:1 http://security.ubuntu.com hardy-security Release.gpg [189B]
Ign http://security.ubuntu.com hardy-security/main Translation-en_US
Hit http://us.archive.ubuntu.com hardy Release.gpg.........
Fetched 964kB in 13s (69.6kB/s)Reading package lists... 
Done

After running the update, we have to run the apt-get upgrade command to update software in our system to the latest update. See an example below:

luzar@ubuntu:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
.........
Setting up mysql-server (5.0.51a-3ubuntu5.4) ...
Setting up libxml2 (2.6.31.dfsg-2ubuntu1.3) ...
Processing triggers for libc6 ...
ldconfig deferred processing now taking place

After the upgrade is finished, we can run apt-get install to install bind9 software package. Here is how the real installation go:

luzar@ubuntu:~$ sudo apt-get install bind9
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  libbind9-30 libdns35 libisc35 libisccc30 libisccfg30
Suggested packages:  resolvconf
The following NEW packages will be installed:  libdns35 libisc35
The following packages will be upgraded:
  bind9 libbind9-30 libisccc30 libisccfg30
4 upgraded, 2 newly installed, 0 to remove and 5 not upgraded.
Need to get 978kB of archives.
After this operation, 1651kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://us.archive.ubuntu.com hardy-updates/main libisc35
 1:9.4.2.dfsg.P2-2 [127kB]
Get:2 http://us.archive.ubuntu.com hardy-updates/main libdns35
 1:9.4.2.dfsg.P2-2 [494kB]
Get:3 http://us.archive.ubuntu.com hardy-updates/main bind9
 1:9.4.2.dfsg.P2-2 [268kB]
Get:4 http://us.archive.ubuntu.com hardy-updates/main libisccc30
 1:9.4.2.dfsg.P2-2 [23.1kB]
Get:5 http://us.archive.ubuntu.com hardy-updates/main libisccfg30
 1:9.4.2.dfsg.P2-2 [38.5kB]
Get:6 http://us.archive.ubuntu.com hardy-updates/main libbind9-30
 1:9.4.2.dfsg.P2-2 [27.5kB]
Fetched 978kB in 15s (63.8kB/s)
Selecting previously deselected package libisc35.
(Reading database ... 
18940 files and directories currently installed.)
Unpacking libisc35 (from .../libisc35_1%3a9.4.2.dfsg.P2-2_i386.deb)
 ...
Selecting previously deselected package libdns35.
Unpacking libdns35 (from .../libdns35_1%3a9.4.2.dfsg.P2-2_i386.deb)
 ...
Preparing to replace bind9 1:9.4.2-10
 (using .../bind9_1%3a9.4.2.dfsg.P2-2_i386.deb
) ...
 * Stopping domain name service... bind                    [ OK ]
Unpacking replacement bind9 ...
Preparing to replace libisccc30 1:9.4.2-10
 (using .../libisccc30_1%3a9.4.2.dfsg.P2-2_i386.deb)
 ...
Unpacking replacement libisccc30 ...
Preparing to replace libisccfg30 1:9.4.2-10
 (using .../libisccfg30_1%3a9.4.2.dfsg.P2-2_i386.deb)
 ...
Unpacking replacement libisccfg30
 ...
Preparing to replace libbind9-30 1:9.4.2-10 
(using .../libbind9-30_1%3a9.4.2.dfsg.P2-2_i386.deb)
 ...
Unpacking replacement libbind9-30
 ...
Setting up libisc35 (1:9.4.2.dfsg.P2-2)
 ...
Setting up libdns35 (1:9.4.2.dfsg.P2-2)
 ...
Setting up libisccc30 (1:9.4.2.dfsg.P2-2)
 ...
Setting up libisccfg30 (1:9.4.2.dfsg.P2-2
) ...
Setting up libbind9-30 (1:9.4.2.dfsg.P2-2
) ...
Setting up bind9 (1:9.4.2.dfsg.P2-2
) ...
Installing new version of config file /etc/apparmor.d/usr.sbin.named
 ...
Reloading AppArmor profiles : done.
 * Starting domain name service... bind                                  [ OK ]
Processing triggers for libc6 ...
ldconfig deferred processing now taking place
luzar@ubuntu:~$

We have successfully installed bind9 package. Now, let's see what version we got:

luzar@ubuntu:~$ named -vBIND 9.4.2-P2
luzar@ubuntu:~$

So that's it. We already have bind9 package installed in our system. What to do next is to configure our dns server.

finger command in Ubuntu

2008-11-30T03:12:00.000-08:00

Linux finger command prints user information in the system. You need to install finger package in order to use finger command because it's not installed by default. The finger command can be a threat to system security because attacker can gain information about the system. You can turn off the finger daemon or do not install it in the first place.

Why are we going to install it now? We need to know how the finger command works and see how it can danger our system. You can install finger using apt-get command as always:

luzar@ubuntu:~$ sudo apt-get install finger
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer
 required:
  libdns32 libisc32Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:  finger
0 upgraded, 1 newly installed, 0 to remove and 2 not upgraded.
Need to get 18.0kB of archives.
After this operation, 77.8kB of additional disk space will be used.
Get:1 http://us.archive.ubuntu.com hardy/main finger 0.17-11 [18.0kB]
Fetched 18.0kB in 0s (18.8kB/s)
Selecting previously deselected package finger.
(Reading database ... 18970 files and directories currently installed.)
Unpacking finger (from .../finger_0.17-11_i386.deb) ...
Setting up finger (0.17-11) ...
luzar@ubuntu:~$

Here is some information about finger command in manual page:


NAME

     finger - user information lookup program

SYNOPSIS

     finger [-lmsp] [user ...] [user@host ...]

DESCRIPTION

     The finger displays information about the system users.

The finger command is a user information lookup program. What information can we see? We can check that later. The syntax can be as simple as finger user to look for local system and finger user@host for looking into remote system. That's powerful isn't it?

Let's see some finger command examples. Here is an example of finger command without any option or argument specified:

luzar@ubuntu:~$ finger
Login     Name       Tty      Idle  Login Time   Office     Office Phone
luzar     luzar      pts/0          Nov 22 03:01 (192.168.1.6)
root      root      *tty1       29  Nov 22 03:00luzar@ubuntu:~$

If no arguments are specified, finger will print an entry for each user currently logged into the system.

Let's say I want to check some information on user name james. I would write the command as:

luzar@ubuntu:~$ finger james
Login: james                            Name: James Labu
Directory: /home/james                  Shell: /bin/bash
Office: 133, 012345678                  Home Phone: 098765432
On since Sat Nov 22 03:38 (EST) on tty2   15 seconds idle
     (messages off)No mail.No Plan.
luzar@ubuntu:~$

I can also use -s to prints in different layout:

luzar@ubuntu:~$ finger -s james
Login     Name         Tty      Idle  Login Time   Office     Office Phone
james     James Labu  *tty2       17  Nov 22 03:38 133        012345678
luzar@ubuntu:~$

Everything we need to know about user information is there, login name, real name, home directory, shell used, office room and phone numbers, etc.

Now let's see another example with useful options. This time it's how to finger remote host. Use the format as in the example below:

luzar@ubuntu:~$ finger james@ubuntu

If you want to remove finger command from Ubuntu system, use the command in example below:

luzar@ubuntu:~$ sudo apt-get remove finger
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer
 required:  libdns32 libisc32Use 'apt-get autoremove' to remove them.
The following packages will be REMOVED:  finger
0 upgraded, 0 newly installed, 1 to remove and 2 not upgraded.
After this operation, 77.8kB disk space will be freed.
Do you want to continue [Y/n]? y
(Reading database ... 19000 files and directories currently installed.)
Removing finger ...
luzar@ubuntu:~$ sudo apt-get update

You can run apt-get update after that. Now test finger command again to if it's still running in our system.

luzar@ubuntu:~$ finger
-bash: /usr/bin/finger: No such file or directory
luzar@ubuntu:~$

That's it, no more finger daemon running.

Command line web browser in Linux

2008-11-30T03:06:00.000-08:00

Lynx is a command line web browser used in many platform other than Linux. Current versions of Lynx run on Unix, VMS, Windows 95/NT, 386DOS and OS/2 EMX. It also support other protocol other than http such as Gopher, FTP, WAIS, and NNTP servers.

In the beginning, Lynx was developed by University of Kansas to distribute campus information. Later, Lynx has been added a feature to browse the Internet by a student named Lou Montulli, and it was released in March 1993.

Here is an example of using Lynx to open a website in the Internet:

luzar@ubuntu:~$ lynx http://linuxservertutorials.blogspot.com

Here is a screenshot of Lynx opened a website in the Internet:

Use Lynx to open Google search engine:

luzar@ubuntu:~$ lynx -accept_all_cookies http://www.google.com

This is a Google search engine screenshot when open with Lynx:

Ubuntu lynx installation guide

2008-11-30T03:01:00.000-08:00

Lynx is a web browser in command line terminal. That means, even in the Ubuntu command line terminal, you can still surf internet and view websites. Lynx is not installed by default during Ubuntu installation. You need to manually install lynx using apt-get install or aptitude install.

Here is an example of lynx installation using apt-get install lynx command:

luzar@ubuntu:~$ sudo apt-get install lynx

[sudo] password for luzar:

Reading package lists... Done

Building dependency tree

Reading state information... Done

The following NEW packages will be installed:

  lynx

0 upgraded, 1 newly installed, 0 to remove and 9 not upgraded.

Need to get 1168kB of archives.

After this operation, 4997kB of additional disk space will be used.

Get:1 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:2 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:3 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:4 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:5 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:6 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Get:7 http://us.archive.ubuntu.com hardy/main lynx 2.8.6-2ubuntu2 [1168kB]

Fetched 143kB in 30min22s (79B/s)

Selecting previously deselected package lynx.

(Reading database ... 28836 files and directories currently installed.)

Unpacking lynx (from .../lynx_2.8.6-2ubuntu2_i386.deb) ...

Setting up lynx (2.8.6-2ubuntu2) ...

luzar@ubuntu:~$

That's all. Now we've got Lynx installed in our system.

ubuntu nmap installation guide

2008-11-30T02:49:00.000-08:00

You can check whether nmap has been installed in your system using apt-get command or check installed database using aptitude command. Enter nmap in the command line terminal, and if you get answer like an example below, that means nmap hasn't been installed in your system.

luzar@ubuntu:~$ nmap
The program 'nmap' is currently not installed.
You can install it by typing:
sudo apt-get install nmap
-bash: nmap: command not found

You can follow Ubuntu advice, install nmap using apt-get install nmap or using your favorite package management. Below is an example of apt-get install nmap command:

luzar@ubuntu:~$ sudo apt-get install nmap
[sudo] password for luzar:Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:  nmap
0 upgraded, 1 newly installed, 0 to remove and 9 not upgraded.
Need to get 1013kB of archives.
After this operation, 3506kB of additional disk space will be used.
Get:1 http://us.archive.ubuntu.com hardy/main nmap 4.53-3 [1013kB]
Get:2 http://us.archive.ubuntu.com hardy/main nmap 4.53-3 [1013kB]
Get:3 http://us.archive.ubuntu.com hardy/main nmap 4.53-3 [1013kB]
Get:4 http://us.archive.ubuntu.com hardy/main nmap 4.53-3 [1013kB]
Get:5 http://us.archive.ubuntu.com hardy/main nmap 4.53-3 [1013kB]
Fetched 129kB in 18min56s (114B/s)
Selecting previously deselected package nmap.
(Reading database ... 28764 files and directories currently installed.)
Unpacking nmap (from .../archives/nmap_4.53-3_i386.deb) ...
Setting up nmap (4.53-3) ...

The nmap package has been successfully installed in your system. If you enter nmap command again, you'll get a long list of help like an example below:

luzar@ubuntu:~$ nmap
Nmap 4.53 ( http://insecure.org )
Usage: nmap [Scan Type(s)] [Options] {target specification}
TARGET SPECIFICATION:  Can pass hostnames, IP addresses, networks, etc.
  Ex: scanme.nmap.org, microsoft.com/24, 192.168.0.1; 10.0.0-255.1-254
  -iL : Input from list of hosts/networks
  -iR : Choose random targets
  --exclude : Exclude hosts/networks
  --excludefile : Exclude list from file
HOST DISCOVERY:
  -sL: List Scan - simply list targets to scan
  -sP: Ping Scan - go no further than determining if host is online
  -PN: Treat all hosts as online -- skip host discovery
  -PS/PA/PU [portlist]: TCP SYN/ACK or UDP discovery to given ports
  -PE/PP/PM: ICMP echo, timestamp, and netmask request discovery probes
  -PO [protocol list]: IP Protocol Ping
  -n/-R: Never do DNS resolution/Always resolve [default: sometimes]
  --dns-servers : Specify custom DNS servers
  --system-dns: Use OS's DNS resolver

That's good. The nmap is already in our system. Now, try scan your own server to see whether it really works:

luzar@ubuntu:~$ nmap -v -A 10.21.35.160
Starting Nmap 4.53 ( http://insecure.org ) at 2008-11-18 22:35 EST
Initiating Ping Scan at 22:35Scanning 192.168.1.6 [1 port]
Completed Ping Scan at 22:35, 0.03s elapsed (1 total hosts)
Initiating Parallel DNS resolution of 1 host. at 22:35
Completed Parallel DNS resolution of 1 host. at 22:35, 0.00s elapsed
Initiating Connect Scan at 22:35
Scanning a3-musang.hitam.com (192.168.1.6) [1714 ports]
Discovered open port 22/tcp on 192.168.1.6
Discovered open port 443/tcp on 192.168.1.6
Discovered open port 80/tcp on 192.168.1.6
...
...
...
Service Info: OS: Windows

Read data files from: /usr/share/nmap
Service detection performed. 
Please report any incorrect results at http://insecure.org/nmap/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 249.926 seconds
luzar@ubuntu:~$