Network Security and Open-Source Blogs

GNU/Linux is a great customizable Operating System, so are we can really customizing to our needs, well, many of us are not bothering to modify the defaults. I found some tweeks while searching for some thing else. Here are some of them which might come in handy at times.

1. Change FileManager: Though nautilus is a great file manager, but some prefer other file managers like a thunar, dolphin, PCMan, etc may be for speed, looks or whatever. Here is a way to do it.
   Open Terminal, type in command gconf-editor to open gnome configuration editor.
   In gconf-editor navigate through / –> desktop –> gnome –> session –> required_components –> double click on filemanager and change the value to new file manager command. You can also change panel, window manager navigating through same path.
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After a GNU/Linux operating system installation, we install a boot loader usually GRUB. For security we prevent single user more and GRUB console but never care for a Windows based OS like XP, if there is one. So the intruder can log into windows and access our data easily. But there is a solution for locking Windows OS like XP, here is how it is,

Open menu.lst file

vi /boot/grub/menu.lst

Replace

title        Windows XP Home
rootnoverify    (hd0,X)
savedefault
chainloader    +1

With

title        Windows XP Professional x64 Edition
rootnoverify    (hd0,2)
savedefault
chainloader    +1
lock
password –md5 <pasword-hash>

Where password-hash can be generated shown below

type in grub as root in command line, a grub console will open, then type this

grub>md5crypt

Password: password

Encrypted: $1$QQwJ9/$p35XqOCfCgrpbQDsFgIaL1 —> This is password-hash for password

This can be extended for other grub entries

Command line is most important for any GNU/Linux advanced user, so why don’t we customize the prompts which is displayed on terminal all the time? well, here is how to do it.

• Primary Prompt is stored in variable PS1,
  1. To view, type the command: $echo $PS1
  2. To modify, type the command: $export PS1=”example:~$”
• Secondary Prompt is stored in variable PS2,
  1. To view, type the command: $echo $PS2
  2. To modify, type the command: $export PS2=”>>”

Here are some handy history related commands,

• history: this command shows the list of commands which were keyed in previously on command line.
  If you want last 10 to be displayed: history | tail -10, ~/bash_history file stores the history.
  E.g. $history | tail -5    —> Displays the last 5 commands keyed in.
• !!: Repeat previous command
  E.g. $!!   —> Executes previously executed command
• !string: Repeat the previous command from the history whose first chars match string
  E.g. $!ca —> Executes the previous executed command starting with ca, say cat command

• !n: Repeat the nth command from the history
  E.g. $!500 —> Executes 500th command in the history file